TRX250R.ORG
General => Pics and Vids => Topic started by: Burns363R on October 05, 2014, 07:12:47 PM
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Was a little lean on top, after 1/2 mile WOT, it was pinging a little bit and wasnt pulling on top quite as hard as it should. But it does run good, very crisp. Float bowl level is everything on these, i need to add a little more to the float level and i think i will have it.
Watch the video and enjoy.
http://youtu.be/RY2d1TopJmw?list=UURhJ3oFnLARwWYVG9fDuWKQ
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Which FMR did you end up using?
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I have the 74. Still lean though. Corey says that they will break in and get richer.
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Still lean though.
Did you richen up the clicker?
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Well the clicker is only ment to do idle to half throttle. You can adjust it and it will help top end but the bike will end up not wanting to idle and be rich down low.
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I havent heard one in person, but all the videos people post using these carbs the bikes sound funny to me.
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It does have a different sound to it. But mostly what your hearing is the GO Pro, I need to do a video with the other back on it that allows for better sound.
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Is the bottom-end improvement really that noticeable with the SC?
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Id say so, im not 100% satisified with it. If i lean up the bottom a little more it will be amazing down low, and it idles without loading up. Very cool.
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I havent heard one in person, but all the videos people post using these carbs the bikes sound funny to me.
Kyles video definitely does sound much lower pitch than in person. At first I just thought it was his pipe. But through the entire video it sounds nothing like Ryan Blacks smart carb video. Mine sounds more like Ryans as the pitch is high sounding (lean). If you set the carb lean down low it wants to rev out much quicker than if you set it to rich. I would say from my experience with the SC all kiehens are set to rich down low. I have now got my Smart carb set way rich and I can lug her down with no problem which is the way the Kiehen preformed. I fear running to lean but in time I believe we will get a FMR (fuel metering rod) made the correct size for WOT. So for now I am 13-15 clicks rich. I will do more plug checks as the outside temperature cools down. Don't want to run WOT if its 100 degree's out and she's runnin lean.
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They all just sound zingy... which might be great but when your are so conditioned to the keihen the change is weird. They might be a little better but I dont think they are there yet. Everyone seems to be struggling with some area.
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It seems to be that if you have a 350cc or below, they are dialed in good. It seems that they are still dialing in the needle for the sizes above that. My 38 cast runs good with my 310cc. It is plumb angry with acceleration. The throttle response is pretty ridiculous. Sounds like you're getting there Kyle. I think alot of people need to keep this is mind and you made a little mention of it with the float bowl level: these are NOT plug and play carbs. They need to be setup and adjusted accordingly just like any other carb. But once they are set, they are good to go. If you buy this carb thinking all you got to do is strap it on and it's perfect for every application already set from the factory, you are kidding yourself. APT doesn't make that boast, yet people seem to think that.
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It is plumb angry with acceleration. The throttle response is pretty ridiculous.
Yep, and he is not kidding. Its like feeding your R a bunch of steroids. You will be surprised how much power is being hidden by your Kiehen carb. You will be asking yourself if someone added 50cc's to your bike.
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Kyles video definitely does sound much lower pitch than in person. At first I just thought it was his pipe. But through the entire video it sounds nothing like Ryan Blacks smart carb video. Mine sounds more like Ryans as the pitch is high sounding (lean). If you set the carb lean down low it wants to rev out much quicker than if you set it to rich. I would say from my experience with the SC all kiehens are set to rich down low. I have now got my Smart carb set way rich and I can lug her down with no problem which is the way the Kiehen preformed. I fear running to lean but in time I believe we will get a FMR (fuel metering rod) made the correct size for WOT. So for now I am 13-15 clicks rich. I will do more plug checks as the outside temperature cools down. Don't want to run WOT if its 100 degree's out and she's runnin lean.
It's funny you say that because my pilot and needle have always been leaner than what most people say they run or whoever the builder is recommends. I can literally count on my hands the number of pilot jet sizes that match mine that I have seen on the forums over the years. Mine is in the low 40's right now and I still feel it is rich, my needle diameter is about the only difference I see in my needle which also affects what most would call the bottom end.
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Id say so, im not 100% satisified with it. If i lean up the bottom a little more it will be amazing down low, and it idles without loading up. Very cool.
Interested to see how you compare the power delivery from the different carburetors you have run and this setup once you get finished adjusting on it.
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It's funny you say that because my pilot and needle have always been leaner than what most people say they run or whoever the builder is recommends. I can literally count on my hands the number of pilot jet sizes that match mine that I have seen on the forums over the years. Mine is in the low 40's right now and I still feel it is rich, my needle diameter is about the only difference I see in my needle which also affects what most would call the bottom end.
You probably have a Keihin carb that has a worn out needle jet. This is a common problem with carbs that have some miles on them. You need to find someone in your area that has bore guages that can measure holes in the .1000" range and has the accuracy of .0001". If you cannot find anyone send me the carb and I can measure the needle jet.
If the needle jet is worn out it is new carburetor time and or you have to keep installing leaner jet needles to try to compensate for the ware in the needle jet. Keihin does not offer replacement needle jets. Mikuni does offer needle jets and typically offers about 50 different sizes to fit each of their models to aid in the fine tuning of their carbs.
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You probably have a Keihin carb that has a worn out needle jet. This is a common problem with carbs that have some miles on them. You need to find someone in your area that has bore guages that can measure holes in the .1000" range and has the accuracy of .0001". If you cannot find anyone send me the carb and I can measure the needle jet.
If the needle jet is worn out it is new carburetor time and or you have to keep installing leaner jet needles to try to compensate for the ware in the needle jet. Keihin does not offer replacement needle jets. Mikuni does offer needle jets and typically offers about 50 different sizes to fit each of their models to aid in the fine tuning of their carbs.
Ya I thought something that at one time, but after one 36PJ, 38PJ, 38 PWK A/S, a handful of 34 PJ's, one new 36 PWK, a few different bottom ends with and without new cranks bearings and seals, a few different cylinders ranging from 100% stock to a 300 PV, a handful of different reed cages new and used, misc pipes, silences with and without new packing, a few different ignition combos and a partridge in a pear tree I have decided mine is just an anomaly over the years so I just put it were it likes it and find something else to worry about in life.
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Yep, and he is not kidding. Its like feeding your R a bunch of steroids. You will be surprised how much power is being hidden by your Kiehen carb. You will be asking yourself if someone added 50cc's to your bike.
You might have just made me spend another $400 this offseason, Puma....:disgust:
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You might have just made me spend another $400 this offseason, Puma....:disgust:
Don't worry I called APT today and from the conversation that we had you probably won't get the cast smart carb until next season starts lol.
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Ya I thought something that at one time, but after one 36PJ, 38PJ, 38 PWK A/S, a handful of 34 PJ's, one new 36 PWK, a few different bottom ends with and without new cranks bearings and seals, a few different cylinders ranging from 100% stock to a 300 PV, a handful of different reed cages new and used, misc pipes, silences with and without new packing, a few different ignition combos and a partridge in a pear tree I have decided mine is just an anomaly over the years so I just put it were it likes it and find something else to worry about in life.
Are you saying that your pilot jets and needles tend to be leaner than most other guys with similar engine packages regardless of what carburetor you are using?
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Are you saying that your pilot jets and needles tend to be leaner than most other guys with similar engine packages regardless of what carburetor you are using?
That's What I gather. I Also am confused
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Are you saying that your pilot jets and needles tend to be leaner than most other guys with similar engine packages regardless of what carburetor you are using?
Correct, similar location and air intake setups also. I just thought it was odd that Tony said he felt most Keihins were rich on bottom after switching to the smartcarb and mine always tended to want a pilot jet smaller than what most were running or recommended. For Example if you took any of the random combos I listed and put a 50 plus pilot in the thing it would have a very poor idle, have a lag coming off idle-1/4ish throttle area and smoke excessively at idle. I chased this for quite a while always wondering, trying different fuels, air filters, filter oils, all kinds of crazy stuff and finally just rode the thing and quit wondering. Never had a failure or a complaint from anyone who has rode it so I suppose it is must be ok. I just still feel like it could run cleaner on bottom which is why I am interested to see what Kyle thinks of the power delivery because he seems to be pretty anal with his jetting.
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After working with big bore cylinders for 10 years you will see the Keihins tend to be too rich on the bottom end. The Polonda wanted to be much leaner than I could be comfortable with. The Shearer in-frame Puma pipe took me hours of time to get close. Using leaner needles and adjusting clip position. Always seemed to be too rich or too lean. I melted the strap over the electrode on my spark plug. But I did learn what too lean feels like. Like the spark plug is popping or snapping each revolution. I finally gave up and hung the Shearer in-frame on the garage wall. I was so very disappointed as this pipe had truly amazing power on the top end. I got the LED in-frame Puma pipe and it seemed to work OK on the bottom end. But after installing the SC it went from OK to simply amazing bottom end snap and power. Never too lean, just right I hope and the top end seems a little lean. They are going to have to make some FMR's which will let more gas into the carb at WOT. Whatever Kyle ends up with I want one richer than that.
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It's funny you say that because my pilot and needle have always been leaner than what most people say they run or whoever the builder is recommends. I can literally count on my hands the number of pilot jet sizes that match mine that I have seen on the forums over the years. Mine is in the low 40's right now and I still feel it is rich, my needle diameter is about the only difference I see in my needle which also affects what most would call the bottom end.
alot of people dont know how to tune a carb. not saying im a expert but some people just really dont have a clue. so if joe blow says he uses 55p, it dont meen sqaut because hes probly got the wrong size in there. there for you cant really gain any perspective from what joe blow says. depending on the circumstances, low 40's pilot isnt uncommon. seems like i got 42p in one of mine bikes. might even have 2 bikes in the low 40's. cant recall off top of my head. youll know when its gets to small. probly start sounding tingy and good chance it wont run with the choke off unless theres a ton of heat in the cylinder, even then it may not run without choke. this is the common pattern ive seen from keihin when pilot is to small
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Don't worry I called APT today and from the conversation that we had you probably won't get the cast smart carb until next season starts lol.
Yea i talked to tom last week about my 38 cast i placed order with on may28. . He said at least 2 more months. But u can spend the 675 and get the billet. Wooooo
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i have a 42 pilot in a ported stroker motor and it runs well from bottom to top.
john
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Yea i talked to tom last week about my 38 cast i placed order with on may28. . He said at least 2 more months. But u can spend the 675 and get the billet. Wooooo
how much do you have to put down as deposit on the pre-order? Tom said I could wait until they get them in stock but I get the feeling they're going to sell out fast.
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well i preorded payed the whole price
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Yeah I went on the site and saw you have to pay full purchase price. I may look into a 38mm lectron possibly
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Did another WOT long pull tonight. Bike felt great. I changed the cover on the Go Pro and you can hear it alot better. The Go Pro is mounted to the handle bars, hence the weird angles when I'm doing wheelies. The pics of the spark plug are from right after killing the throttle when i came back into the garage. Looks pretty good to me. sounds like we have a winner.
http://youtu.be/lBFdg-jGZ98?list=UURhJ3oFnLARwWYVG9fDuWKQ
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191856_zpseqpadeu3.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191908_zpsrmzu9vai.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191930_zpsa7qvppgh.jpg)
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Why dont the videos imbed on this site?
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Nice! She looks ready now. Bring on the 4 pokes
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What was the trick to setting the float height?
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Fill the carb up and take the body off the bowl and measure the fuel level.
Or put a tube on the bowl drain and open the drain with the tube going back up toward the top of the carb so you can get a bowl reading. Cory told me 22mm down from the gasket face. I found that my bike like the 17mm level better. Basically it allows the needle to fall farther from the seat and allow more fuel flow under WOT.
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wow that's one LOOOONG wot..but it sounded great...
Id be afraid to open one for that long...do you have a temp gauge if so what was your temp once you parked it??
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Cory told me 22mm down from the gasket face. I found that my bike like the 17mm level better. Basically it allows the needle to fall farther from the seat and allow more fuel flow under WOT.
Where was it set when the carb ran out of fuel?
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28mm maybe? I cant remember, but it was wrong because the tab was pushed down below plane of the rest of the float system. It should at plain or slightly farther away from the body.. This is the tab that controls the float. If any of that even makes sense in typing.
I have a temp gauge on it. Maybe 160? It was way to cool IMHO for as long as it ran. I probably idled for 5 minutes before i went out on it. outside air temp is 60, so that plays a big factor. And i have switched to a BB stinger on my pipe, so temps should be down.
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28mm maybe? I cant remember, but it was wrong because the tab was pushed down below plane of the rest of the float system. It should at plain or slightly farther away from the body.. This is the tab that controls the float. If any of that even makes sense in typing.
I went through the adjustment process to keep the carb from flooding. I never got an answer from APT why the float level effected the fuel delivery rate. Thanks for the info Kyle! Just want to know in case I run out of fuel again.
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Yep, starting to sound better now. Tony, as Kyle described on the float bowl, I had the same conversation with Corey as well. That is why float level is so important, probably even more so on a modified engine. That's why that is one of the first things to check in the instruction manual. Is it bothersome to do when you first get your carb and you just want to put it on and rip? Yes, but it is worth taking the time to do.
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The instruction manual said nothing about float level based on engine performance, just checking for to make sure it doesnt overflow. FYI.
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Im wondering what the performance would be like if you run to rich of metering rod. Im awaiting a text back from Cory. I was lean to start so i put my 74 FMR in, and then i raised the bowl. Obviously the plug looks great and the bike runs great, but i still feel its missing something. I wonder if i need to step the FMR back now. With the way these FMR work, the carb will adjust the fuel based on the engine demand, but if its not using a optimized FMR, you may not get the best atomization off of it.
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The instruction manual said nothing about float level based on engine performance, just checking for to make sure it doesnt overflow. FYI.
I never said that it did. But if it is somehow off from the factory (somehow bumped or accidentally changed through assembly or packaging or whatever) then it could negatively affect performance. That is ONE of the reasons they have you check it once you get it. And yes, overflowing would be a negative as well. lol
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It sounds like to me, if a simple power jet was added you could easily fix the topend lean issue some guys are having, even Honda used power jets in the late 90's but they had elec versions that would turn on and off.
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Did another WOT long pull tonight. Bike felt great. I changed the cover on the Go Pro and you can hear it alot better. The Go Pro is mounted to the handle bars, hence the weird angles when I'm doing wheelies. The pics of the spark plug are from right after killing the throttle when i came back into the garage. Looks pretty good to me. sounds like we have a winner.
http://youtu.be/lBFdg-jGZ98?list=UURhJ3oFnLARwWYVG9fDuWKQ
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191856_zpseqpadeu3.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191908_zpsrmzu9vai.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141008_191930_zpsa7qvppgh.jpg)
It sounds like the engine is slightly rich on that mile long plug chop. Maybe it is the camera's microphone but I think I can hear a rich missfire at the peak RPMs.
From the looks of the video it looks like you are running about 70 MPH or less. With the gearing you are running the engine will be running way past the power peak and may act rich and give inaccurate plug readings. The tip of the spark plug shows rich from what I can see in the pictures. We really need to be looking at the spark plug under a 2 to 5 power magnification. The spark plug steel shell shows the combustion temperatures were in the ballpark somewhere in the RPM range but the spark plug porcelain tip was too cold the last 15 seconds or so of operation. The porcelain tip showing rich may also be due to running a heat range that is too cold. Trying to read a spark plug for best combustion temperature is meaningless if the heat range is not correct. Is that a B9ES spark plug?
If you changed the gearing to increase the speed about 15 to 20 mph, I think that the spark plug would show a more accurate reading of the mixture on top end that produces the best acceleration and is safe while the engine is under acceleration.
Summary:
Be careful reading spark plugs on plug chops that do not imitate running the engine (loading the engine) the same way it will be raced or used. If you ride/race the quad where the engine is spending most it it's time in the over-reved state like shown in the video, I think that the jetting is rich and safe at that RPM. If you ride on a track where you spend most of your time accelerating through the gears and then breaking for corners and such, I would suggest revising your method of testing for determining the correct air/fuel mixture by reading spark plugs.
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I appreciate the input Jerry. I will be trying a slightly leaner FMR tonight and see how it performs. I feel that it is also rich on top. The motor feels like its being held back. But that gearing and tires in combination with the 2" of loose sand may be putting to much load on the bike. I feel like it should rev out better. I believe that is a B8 Plug. I will go to a B9 which i usually run, but switched to the the b8 in an attempt to stop detonation
My goal with this test is to make sure it wont melt down in the open fields that occur during harescramble racing.
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I will be trying a slightly leaner FMR tonight and see how it performs. I feel that it is also rich on top.
Oh man, you had me real worried there Kyle. I have been trying to richen up the lower end to get the top end richer. My plug chop was extra white at WOT. I am a little confused since you did not pull the plug at WOT but after returning to the garage.
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I was WOT up until right before the garage, and i coasted most of the way into it.
I didnt get a chance to change needles last night. I will tonight.
Tony, you really need to know which FMR you have in your bike.
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Tony, you really need to know which FMR you have in your bike.
You know how frustrating it is to talk to Tom the one that answers the phone. He is very nice to talk to but I get the feeling he is not a tech.
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Agreed, he doesnt know his stuff. Cory has been really helpful for me. He recommended me going back and trying the 76 now that i have proper fuel flow.
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Agreed, he doesnt know his stuff.
Tom told me to set the float level 1/4" below the top of the float bowl. The manual says 17mm and he says 6mm. I misplaced Cory's phone number damn it. Do you know his cell #?
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Corey cell - 307-761-1251. I try to only talk to Corey. He is very helpful.
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Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.
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Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.
Kyles, if I remember correctly, 22mm is also what the manual says and is normal for most applications. However, I think if you have a strong "sucker", then 22mm is not enough to keep up with the demand.
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Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.
Yes, Its frustrating taking it off and make an adjustment than does not do anything different. Pardon me on the manual quote of 17mm. It is actually 20mm, just over 3/4". I checked it before installing the carb so I should be good. Still seems lean, but maybe I am just used to too rich.
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Have you done any plug chops lately, Tony? If so, can you post some pics. Maybe we can help.
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Have you done any plug chops lately, Tony? If so, can you post some pics. Maybe we can help.
I will do them tomorrow. I keep forgetting to put a new kill switch in.
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I will go to a B9 which i usually run, but switched to the the b8 in an attempt to stop detonation
My goal with this test is to make sure it wont melt down in the open fields that occur during harescramble racing.
the B9 will be less prone to promoting pre-ignition and detonation because it runs cooler than the B8, but the B8 is less likely to foul
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The bike had a B9 in it anyways. Yes the higher the number the colder the plug, which leads to less detonation caused from the plug (detonation can be caused by other things obviously). But easier fouling. I said that wrong.
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Oh man, you had me real worried there Kyle. I have been trying to richen up the lower end to get the top end richer. My plug chop was extra white at WOT. I am a little confused since you did not pull the plug at WOT but after returning to the garage.
A white spark plug is not an indication of being lean. A white spark plug is an indication of the amount of time on the spark plug and the temperature of the porcelain since the spark plug was installed. If Kyle puts a new spark plug in his engine that is rich enough to miss-fire and made ONE short WOT pass, the porcelain will come out looking like a new spark plug. It takes some time for the porcelain to turn tan on a well tuned carburetor. If your spark plug turns tan in one short plug chop pass the porcelain temperature is too high. High porcelain temperatures are due to excessive combustion temperatures or a heat range that is too hot. High combustion temperature is ok as long as the engine is properly designed/developed and not experiencing any detonation.
Using an eye loop magnifier to read spark plugs is essential if you are attempting to find the main jet size that will produce the most power before piston killing detonation occurs. Using an eye loop will allow one to see indications of slight detonation before you get to the point that you hurt a piston. If your engine is rich enough to miss-fire at high RPMs it is a waste of time looking at the spark plug unless something is wrong with your build that causes it to experience detonation as it is pulling up through the low to mid RPM range.
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It sounds like the engine is slightly rich on that mile long plug chop. Maybe it is the camera's microphone but I think I can hear a rich missfire at the peak RPMs.
From the looks of the video it looks like you are running about 70 MPH or less. With the gearing you are running the engine will be running way past the power peak and may act rich and give inaccurate plug readings. The tip of the spark plug shows rich from what I can see in the pictures. We really need to be looking at the spark plug under a 2 to 5 power magnification. The spark plug steel shell shows the combustion temperatures were in the ballpark somewhere in the RPM range but the spark plug porcelain tip was too cold the last 15 seconds or so of operation. The porcelain tip showing rich may also be due to running a heat range that is too cold. Trying to read a spark plug for best combustion temperature is meaningless if the heat range is not correct. Is that a B9ES spark plug?
If you changed the gearing to increase the speed about 15 to 20 mph, I think that the spark plug would show a more accurate reading of the mixture on top end that produces the best acceleration and is safe while the engine is under acceleration.
Summary:
Be careful reading spark plugs on plug chops that do not imitate running the engine (loading the engine) the same way it will be raced or used. If you ride/race the quad where the engine is spending most it it's time in the over-reved state like shown in the video, I think that the jetting is rich and safe at that RPM. If you ride on a track where you spend most of your time accelerating through the gears and then breaking for corners and such, I would suggest revising your method of testing for determining the correct air/fuel mixture by reading spark plugs.
New Run. New plug B9ES slightly leaner setting, but not much, 3 clicks leaner. Same 1/2 mile down and back run, motor was warm before the new plug was installed and ran.
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141010_122625_zps398ha4wd.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141010_122643_zps62gkv2kf.jpg)
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New Run.
Yep, thats they way mine looks
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The pic doesnt do it much justice, it was pretty white at the base of the electrode.
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might be time for newer technology. seems plug chops are misleading and are far from a precise science.
john
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New Run. New plug B9ES slightly leaner setting, but not much, 3 clicks leaner. Same 1/2 mile down and back run, motor was warm before the new plug was installed and ran.
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141010_122625_zps398ha4wd.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/20141010_122643_zps62gkv2kf.jpg)
Now look at the porcelain with a magnifying glass and look for any microscopic specks that may look like microscopic pepper specks. The specks are aluminum from the outer edges of the head and piston. Detonation erodes the outer edges of the piston and head and collects on the porcelain surrounding the center wire of the spark plug . Specks that look like fresh aluminum were deposited on the spark plug in the last 30 seconds or less of engine operation. Black or brown specs are older aluminum specks that been coated with a film of carbon, turning them to a darker color.
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I noticed at WOT in 6th gear i can hit top speed at half throttle, any more throttle and it bogs, or doesnt pick up RPM per say.
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The pic doesnt do it much justice, it was pretty white at the base of the electrode.
You have to remember that a spark plug is NOT an instrument that measures power, acceleration, air/fuel ratio, throttle position, RPM or combustion pressure or temperature.
We can only observe the operating temperature of the spark plug and any deposits that accumulates on it. That is all were can conclude from looking at a spark plug.
Reading sparks plugs requires a lot of painful and expensive past experience with a particular engine. Every engine package produces spark plugs that have their own unique look. We have to associate what the spark plug looked like on that engine package when all of the conditions are duplicated when that test or reference engine produced it best power and was tuned so that it would not hurt itself.
The soot ring being present, absent or how long the soot ring is at the base of the porcelain does not tell us anything about the state of tune (power or Air fuel ratio) the engine is experiencing. It only tells is that the spark plug is operating at a temperature that will burn off or not burn off most of fresh mixture that is coming in contact with this very hot surface on the porcelain. If a soot ring is present at the base of the porcelain it is only because that portion of the spark plug is not hot enough to keep the soot burned off.
Summary:
Tune the engine so that if runs well and monitor the spark plug for detonation. An engine that is a highly developed (a design that has all of the bugs worked out) will not usually hurt it self as long as it does not experience detonation. If you are having problems seizing pistons and not experiencing detonation you need to find the design flaws in your engine package. Getting the bugs worked out is usually the responsibility of the engine designer or engine builder. If or when changes are made to the engine package, the person making those changes is responsible for getting the new bugs worked out.
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might be time for newer technology. seems plug chops are misleading and are far from a precise science.
john
Reading spark plugs has never been a science. Only those with limited tuning experience believe it is a science. Spark plug reading is an art if anything. You only acquire an eye for spark plug art or can be critical of the art after many expensive art lessons.
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I noticed at WOT in 6th gear i can hit top speed at half throttle, any more throttle and it bogs, or doesnt pick up RPM per say.
It sounds like a carb that has too big of a main jet or a carb that is too large of the engine. I doubt that the carburetor is too big. A healthy 363 needs a carb in the 40 to 44 mm range.
Do you have any needles that have the same mixture at all the other settings but leaner at only WOT. When you turn the clicker doesn't the whole needle move up or down? If this is so, you are leaning or enriching the needle at all throttle settings. It sounds like you may be experiencing some of the same problems that I experienced when attempting to tune the new Lectrons 35 years ago.
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Jerry how accurate is reading piston wash in your opinion? Like sticking a bore scope in the plug hole and looking after some operation or simply pulling the head? Would something like this give him a better idea of what is going on after short runs like that or does it need to run for longer periods of time? Not something I am real familiar with other than looking at the piston when I have had mine apart so I am interested to see what your thoughts are. Please keep this updated Kyle it is interesting following the process and reading Jerry's input also.
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Cory has been really helpful for me. He recommended me going back and trying the 76 now that i have proper fuel flow.
Today when I went to the mailbox I got a new FMR from APT. SWEEEEEEEEEEET. They sent me a 76. Is that leaner or richer than the 74?
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Leaner. I ran a 76 today and it was lean. I'm going back to a 74 for more testing tomorrow. Corey told me they have a 72 now so I may end up there. We'll see. I want to dominate the harescramble sunday.
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Leaner. I ran a 76 today and it was lean.
I asked for a richer FMR. I told Tom I was making around 80 HP. I must have been shipped with a 78 then? What size FML was your 40mm SC sent with Kyle?
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It had the standard sma one on the other scale they used I think. Mine came with a 78 and 76 rod to. My carb was used and the previous owner gave up. I ran the stock needle and then went straight to the 76
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Honestly just try the needle. I think that your engine combo will respond differently than mine. There's a lot more going on here than straight flow and orifice low pressure draw like a standard carb. It uses pressure signals from the engine to determine fuel demand. And I dont fully understand it.
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It sounds like a carb that has too big of a main jet or a carb that is too large of the engine. I doubt that the carburetor is too big. A healthy 363 needs a carb in the 40 to 44 mm range.
Do you have any needles that have the same mixture at all the other settings but leaner at only WOT. When you turn the clicker doesn't the whole needle move up or down? If this is so, you are leaning or enriching the needle at all throttle settings. It sounds like you may be experiencing some of the same problems that I experienced when attempting to tune the new Lectrons 35 years ago.
My understanding is this is alot like a Lecton. But there is no jet. You slide the FMR up or down to control idle to 1/2 throttle. 1/2 to full throttle I determined by the FMR itself.
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It had the standard sma one on the other scale they used I think. Mine came with a 78 and 76 rod to. My carb was used and the previous owner gave up. I ran the stock needle and then went straight to the 76
Thanks, I am not familiar the the # system being used. It looks like the smaller the number the more fuel is allowed to go to the motor. I understand big cylinders pull more air and can use smaller jets.
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http://youtu.be/lBFdg-jGZ98?list=UURhJ3oFnLARwWYVG9fDuWKQ
from 1:02 to about 1:30 was that full throttle ? also on every plug chop ive ever tried it left a distinct burn mark on the ground strap, usually near the bend or slightly before it going towards the base. i dont see that burn mark in any of these pictures
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No i worked the throttle several times in where the trees are at.
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actually it was more like 1:20-1:35 or so in the open area. sounds like its not reving out all the way but i wasnt sure if it was full throttle or not
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I noticed at WOT in 6th gear i can hit top speed at half throttle, any more throttle and it bogs, or doesnt pick up RPM per say.
What RPM does your engine make it's peak power?
What RPM is your engine turning in 6th gear while you are going down the turn row at WOT?
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What RPM does your engine make it's peak power?
What RPM is your engine turning in 6th gear while you are going down the turn row at WOT?
I ask this question because I suspect that your gearing is way off for the amount of power your engine is making and having the need to run it at sustained top speed.
A big bore kit will go the same speed as a 250 if they are both turning 7500 RPM with the same gearing and tires, providing both engines have enough power to overcome the rolling resistance and aerodynamic resistance at that RPM.
The majority of the highly modified two strokes need a lot less fuel once they go pass the RPM where they make their peak power. Mikuni carburetors have an adjustable air correction jet that can help this problem but the Keihin dirt bike carburetors (PJ, PWK, PWM and Air Strikers) do not have this nice feature. Even when the air correction jet is properly tuned, it cannot make the abrupt fueling change needed to properly lean the mixture in the RPM range past the power peak. I suspect that you may be expecting the smart carb to do something magical and provide this abrupt fueling change that the Lectron, Mikuni, Keihin or any of the other non electronically controlled carburetors have not been able to do. I do not see anything in the Smart Carb design that would allow it to make this abrupt fueling change.
Like Dave RSS396 said in an earlier post, some of the 250 moto-cross and road racing two strokes had electronically controlled power jets. The power jet is turned on typically around 6000 RPM and operates in tandem with the main jet at WOT up to the RPM range where the power peak occurs. Once the engine reaches a RPM in the region where the power peak occurs, the power jet is shut off and the resulting mixture is much leaner. A fuel curve shape like the one just described, fits the fueling requirements of the majority of high performance two-stokes much better than what conventional carburetors can provide.
Most two stroke engines can be a little rich in the RPM range before the power peak without appreciably affecting the power in this range. A two stroke that is rich after the power peak will not rev and may have a rich miss-fire. The majority of the highly modified two-strokes I have worked with will be too lean in the RPM range before the power peak if we install a main jet that supplies the correct amount of fuel in the RPM region past the power peak. An engine that has the mixture correct in the RPM range past the power peak will have good over-rev and will run clean in this RPM range.
Knowing these facts forces us to make a choice of how we tune our carburetors, gear our bikes and then ride our bikes. Once we make these tuning and gearing choices we must ride our bikes in a manner for which it was tuned.
Tuning state #1.
If we ride our bikes on a closed course track where we never reach a speed in top gear where the engine will need to rev past the power peak, we can install a main jet that will produce the best power and acceleration up to an a few hundred RPM past the power peak. If we take this engine package and gearing and try to run it WOT in top gear where it will try to rev a 1000 RPM or so past the power peak, it will probably have a rich miss-fire in that highly over-reved RPM range.
Tuning State #2
If we decide to take our closed course bike and not change the gearing and just run it WOT in 6 gear we can usually lean the main jet and get a few more MPH and not hurt the engine. With this leaner main jet the engine will probably be too lean in the RPM range before the power peak and we may hurt a piston if we ride it with these carburetor setting on a closed course or pull a hill where the engine is pulled down to the RPM range below the power peak.
Tuning State #3 If we want to do most of our running at top speed and get our highest top speed, we can use our carburetor setting and maybe richen it up a jet or two over what we used in tuning state #1, providing we take enough teeth off of the axle sprocket or add teeth to the counter shaft sprocket so that when we run it WOT in 6th gear, the engine peaks or does not have enough power to pull no more than a hundred RPM or so past the power peak.
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Leaner. I ran a 76 today and it was lean. I'm going back to a 74 for more testing tomorrow. Corey told me they have a 72 now so I may end up there. We'll see. I want to dominate the harescramble sunday.
Ran the 76 on Sunday. May be too rich at WOT but I wanted to make sure I was not damaging my Piston. First pass it was loading up and the pics was too dark. Second pass was good heres the best pic.
(http://i59.tinypic.com/ly9ev.jpg)
This was the first pass
(http://i60.tinypic.com/24br8tt.jpg)
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:popcorn:
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:popcorn:
Hell yes I bought another one. If you don't get a smart carb you are missing the 250r reality check. You thought your bike was cool. Now it can be simply amazing!!!!!!!! Ask Kyle or Ryan, they are racing and can tell you what you have been missing!!!
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I dont wanna hijack the thread. I have been seriously considering placing an order and you guys almost have me sold; but is the fuel efficiency really that much better as claimed by APT? I know its not usually a priority with these bikes but I do go on some wicked long trail rides and would sure like to get some better mpg's lol.
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Tony, these threads are why I joined this forum. I think its great people are still making stuff for our rides and that some of us have the guts( and $$) to try them out and are willing to share the knowledge with the rest of us. Sometimes when I read what Jerry writes I can actually feel the exact moment my head starts to expand lol
Sent from my EVO using Tapatalk
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Most two stroke engines can be a little rich in the RPM range before the power peak without appreciably affecting the power in this range. A two stroke that is rich after the power peak will not rev and may have a rich miss-fire. The majority of the highly modified two-strokes I have worked with will be too lean in the RPM range before the power peak if we install a main jet that supplies the correct amount of fuel in the RPM region past the power peak. An engine that has the mixture correct in the RPM range past the power peak will have good over-rev and will run clean in this RPM range.
Knowing these facts forces us to make a choice of how we tune our carburetors, gear our bikes and then ride our bikes. Once we make these tuning and gearing choices we must ride our bikes in a manner for which it was tuned.
Tuning state #1.
If we ride our bikes on a closed course track where we never reach a speed in top gear where the engine will need to rev past the power peak, we can install a main jet that will produce the best power and acceleration up to an a few hundred RPM past the power peak. If we take this engine package and gearing and try to run it WOT in top gear where it will try to rev a 1000 RPM or so past the power peak, it will probably have a rich miss-fire in that highly over-reved RPM range.
Tuning State #2
If we decide to take our closed course bike and not change the gearing and just run it WOT in 6 gear we can usually lean the main jet and get a few more MPH and not hurt the engine. With this leaner main jet the engine will probably be too lean in the RPM range before the power peak and we may hurt a piston if we ride it with these carburetor setting on a closed course or pull a hill where the engine is pulled down to the RPM range below the power peak.
Tuning State #3 If we want to do most of our running at top speed and get our highest top speed, we can use our carburetor setting and maybe richen it up a jet or two over what we used in tuning state #1, providing we take enough teeth off of the axle sprocket or add teeth to the counter shaft sprocket so that when we run it WOT in 6th gear, the engine peaks or does not have enough power to pull no more than a hundred RPM or so past the power peak.
Cool stuff Jerry. What would really drive your point is if you could dig up a 250R dyno graph. Overlay a tad rich run to leaner side run, show hp shift with no real dip in peak hp. Then arrows in the hp graph for "You are here, Tuning State #1, Tuning State #2, Tuning State #3.
That would be a good visual
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I dont wanna hijack the thread. I have been seriously considering placing an order and you guys almost have me sold; but is the fuel efficiency really that much better as claimed by APT?
No unburnt fuel go out the exhaust is what I am guessing you are referring to. So yes, it does make the bike fuel efficient. Whats funny is I know our bikes are plagued with black sludge leaking out the exhaust flange. Well this carb should fix that problem. No need for a thicker gasket cause no unburnt fuel goes out the pipe. I don't think Kyle minds the replies here. We are waiting for him to get a richer metering rod priority mail.
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Cool stuff Jerry. What would really drive your point is if you could dig up a 250R dyno graph. Overlay a tad rich run to leaner side run, show hp shift with no real dip in peak hp. Then arrows in the hp graph for "You are here, Tuning State #1, Tuning State #2, Tuning State #3.
That would be a good visual
I will try to find some dyno runs that are examples of of what I have been talking about.
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I started looking for some dyno runs as examples to some of the situations I have been talking about. This may take a while to find exact examples because the dyno this computer is hooked up to has over 22,000 dyno runs on it and I have four dynos with their own computers and dyno runs. I have not tried to import files or pictures to this site so I may need some help displaying the information.
The first group of runs I want to post shows the effect of having a main jet that is rich (run 013) but not rich enough to miss-fire at the extreme high rpm range. There are a couple of runs that are a little rich (run 010, 016) and a run (run 007) that has the main jet for max power. This engine is in a very mild state of tune and very forgiving on its response to different main jets.
Make note that the front side of the curve in the 5000 to 6500 range is not affected very much by being a little rich. Having the mixture correct after the torque peak tends to produce the most peak power and better power after the torque peak allowing the engine to make the best power over the widest rpm range. These curves are not exactly what I was looking for but are a close approximation to the situation described in tuning state #1 above.
(http://forums.trx250r.org/vbulletin_imports/460_3521_2017-04-18_8586.jpg)
If we look closely the 178 main jet produces the best power in the 5000 to 6750 range and the 170 main jet produces the most peak and the best over run power. A carburetor with an adjustable air correction jet could probably be tuned so that one main jet with the proper air correction jet could produce a power curve that would give the front side of the curve of the 178 main jet and the power after the torque peak that the 170 main jet produced with the 39PWK.
(http://forums.trx250r.org/vbulletin_imports/460_3528_2017-04-18_8256.jpg)
Click on this: It gives the run number, jet size and line color. I am sorry the lines of the graph are so skinny and pale, it makes it difficult to see the distinct line colors.
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Green rich not miss fire, red/blk rich not peak pwr, blu peak pwr. You can see, that the 178 (red) produced better power lower in the rpm range but 170 produced more, power after and beyond.
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170 being blue.
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Damnit guys! More are leaning towards this carb. Maybe a Christmas gift!
I am still taken back by the price. Some 4bbl carbs don't even cost as much as this tiny thing but to hear these testaments is selling it.
Thanks for the words.
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sorry for a dum question. what is a apt carb and how does it work?
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sorry for a dum question. what is a apt carb and how does it work?
It senses the atmospheric pressure you are in. Then provides fuel to your motor. It uses the air pull the motor creates to provide the sufficient amount of fuel needed at any given point in time. No jetting required. Set it and never have to worry about it again.