TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: rablack21 on February 16, 2014, 11:31:19 AM
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I only got a sec to open this thread with, but there will be much more info to come soon! For now, here are some pics of it installed on my R. By the way, Here is the specs of the quad that the smart carb went on:
ESR 310cc power valve
Vforce 3 with new reeds
B8es plug
CR250 ignition
14:1 CR, 110 race fuel
Sparks MX exhaust
(http://forums.trx250r.org/vbulletin_imports/100_657_2017-04-18_3634.jpg)(http://forums.trx250r.org/vbulletin_imports/100_658_2017-04-18_8905.jpg)(http://forums.trx250r.org/vbulletin_imports/100_659_2017-04-18_5590.jpg)(http://forums.trx250r.org/vbulletin_imports/100_660_2017-04-18_1913.jpg)(http://forums.trx250r.org/vbulletin_imports/100_661_2017-04-18_1464.jpg)(http://forums.trx250r.org/vbulletin_imports/100_662_2017-04-18_1653.jpg)(http://forums.trx250r.org/vbulletin_imports/100_663_2017-04-18_4241.jpg)(http://forums.trx250r.org/vbulletin_imports/100_664_2017-04-18_5163.jpg)(http://forums.trx250r.org/vbulletin_imports/100_665_2017-04-18_5316.jpg)(http://forums.trx250r.org/vbulletin_imports/100_666_2017-04-18_3518.jpg)
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There are also some pics thrown in there of my Keihin 38mm A/S that I replaced.
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You must be stoked. I hope it's everything you expect.
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will be watching to see how this goes for you. The smart carb interests me. what are you going to do with the a pwk as
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Nice!
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Can't wait to here some results
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(http://www.4smileys.com/smileys/food-smileys/popcornsmiley1.gif) (http://www.4smileys.com)
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Alright folks, I have much to reports. So I will try to include as much info as possible, but this will take several posts. I know alot of you have been watching with anticipation. I will start with Installation:
1. Installation:
Installation was very easy with just a couple minor issues. The carb inlet-outlet length was exactly the same as my Keihin 38mm A/S so the fitment was just the same. It fit very well in the reed cage and air filter boots. The issue I ran into was that my throttle cable was not long enough. I got this cable about 10 years ago and for some reason it didn't have enough adjustment to let the slide drop all the way down in the carb. But I had bought a new replacement cable to keep on hand, so I tried it on the carb and it worked just. If you look in my posted pics, take notice of the cable that has the extra cable adjustments right there about 10 inches away from the thumb throttle. This was the new replacement cable that I had on hand. This is the one that everyone recommends to buy when you need a new cable. I don't know why my old cable didn't work other than maybe it was made specifically for my Keihin carb. Anyway, with the new cable mounted, the carb slide was good to go.
*Point of note about fitment and adjustment.
The adjuster screw for cable length that screws to the top of the carb and has a jam nut that is recessed in the carb body. See pics. The directions say to tighten this jam nut using snap ring pliers. This method does not work very well, and I found this nut very difficult to get tight enough to keep it from vibrating loose. I think that a full size nut needs to be used in place of the jam nut, so the depth of the nut will sit high enough out of the carb recess to get a hold of it with a wrench. For the time being, I tighten mine by tapping the nut with a chisel on the corner of the nut and using a tad bit of loctite.
With that said, this completes all the issues/inconviences that I ran into with this carb. The cable thing may just be a fluke or have nothing to do with APT at all. The jam nut adjustment issue, I feel could have been done a better way. But, at least it is a minor issue.
(http://forums.trx250r.org/vbulletin_imports/100_722_2017-04-18_2110.jpg)(http://forums.trx250r.org/vbulletin_imports/100_723_2017-04-18_1637.jpg)
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I agree that you should just put a taller nut on it or even make one if needed since you do not need to make a adjustment there, but then you could just red locktite it, that way it does not need to mechanically tight but yet the nut will not move.
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I agree that you should just put a taller nut on it or even make one if needed since you do not need to make a adjustment there, but then you could just red locktite it, that way it does not need to mechanically tight but yet the nut will not move.
You do actually need to make an initial adjustment there, but once it is made, then, yes, it could be loctited down, which is what I did. It did take some adjusting to get the thumb throttle to open the whole throat of the carb. I am running a 400 ex thumb throttle and it just barely has enough travel. And yes, the cavity of the thumb throttle has been ground down as much as possible. I may switch to another thumb throttle I have liked mine for a while.
I will update with some more initial observations very soon. Gotta find time and still get some work done! lol. Bare with me. I know you all want to know how it runs, and I will fill you in very soon. I will say, there is much to be excited about!
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Whoops didnt aee that you ground it down already
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Very cool. Looking forward to reading how the setup and tuning goes.
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First Start/Ride:
A couple kicks and it fired up.
Observations:
1. It smoked a little but not very much. Much less than before
2. throttle is super crisp, revs very freely
3. Throttle return spring is very light, lighter than my keihin with some coils cut off
4. Isn't not idling well, sometimes dies. According to instructions, this is normal/expected.
I finish waiting for it to warm up and take it down the road. I haven't touched the mixture knob yet at this point.
Observations:
1. throttle response is very crisp
2. Powerband is smoother than before, the initial hit is a little softer more relaxed
3. Engine carries itself well even at low rpms.
4. Over rev is more noticeable. Previously, my other carb would fall on it's face and sound almost like a miss with I would over rev it. Now the engine still pulls in over rev, not a great deal, but noticeable. And the engine still sounds like it is handling the fuel better.
At this point, some questions you may ask:
Does it have more power than before? Uncertain yet, but I would definitely say it has more usable power
Does it get better fuel mileage like claimed? Don't know, only have ridden it in a small area of woods by my subdivision. Haven't been out to the track yet.
Next I will post up my experience with playing with the mixture clicker. Guys, feel free to ask me any questions you like if I forget something. I don't have a video yet. I will have a race video to post after this weekend.
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In my experiences, slightly more fuel on the bottom end makes good torque and slightly less fuel on the topend makes best power.
Maybe Mr Hall can share his tuning experiences
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First Impressions/Experiences getting to know the Smart Carb:
Ok. So here's my experience thus far after playing with the mixture screw a bit and running it some. Again, bear in mind, all I can tell you is how it "felt" to me. This is my feedback.
I richened the screw 5 clicks and then rode it. The bottom end "hit" came on a little stronger but seemed like at a slightly later rpm. The top end also seemed to be a little stronger.
I richened 5 more clicks and repeated. Again, the bottom end "hit" was just a tad stronger, but about the same rpm as before. But it seemed noticeable that the top end was again pull harder.
I then put it back in the factory set position, and then went 5 clicks to the lean side. The bottom end was very responsive! I would say "violent" but more instant. The "luggability" increased quite a bit. The power band "hit" has been reduced, not quite as strong/pronounced. The top end was also smooth to the point of feeling like it pulled less hard. The engine has also gone to a more solid monotone sound through out the rpm range.
The changes I notice are more pronounced on the idle-midrange than the midrange-WOT, even though it feels like there is a little bleed over.
It's almost like you are tuning the powerband instead of the carb. It really feels interesting how the power changes as you richen/lean the mixture screw. No, I haven't used it enough yet to find the "sweet spot" or my preference, for that matter.
Again, please keep in mind, I have had limited time riding this, so these are my first impressions from experiments.
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Tuning the power band....sounds like a different thread, LOL. Doug was saying when he leaned it up (idol circuit) seemed to really wake it up! I am hoping to play with the billet 40mm smart carb this weekend. Keep us up to date. The guy on the other site had nothing positive to say.
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In my experiences, slightly more fuel on the bottom end makes good torque and slightly less fuel on the topend makes best power.
Maybe Mr Hall can share his tuning experiences
seems like if your rich on the top it knocks your rpm down alittle also
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I agree with the tuning the powerband comment
My billet 36mm is same way
Richen and top end pulls harder, lean and bottom end is insane snappy
Find the middle point and you get both. Try less clicks.
1 click makes a big difference
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Great review so far!
I wonder if something like this would work better on the cable adjustment? http://www.mcmaster.com/#thumb-screw-nuts
I'm guessing the thread is about M6?
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Great review so far!
I wonder if something like this would work better on the cable adjustment? http://www.mcmaster.com/#thumb-screw-nuts
I'm guessing the thread is about M6?
Something like this would probably work as long as it fit down in that recessed area.
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I agree with the tuning the powerband comment
My billet 36mm is same way
Richen and top end pulls harder, lean and bottom end is insane snappy
Find the middle point and you get both. Try less clicks.
1 click makes a big difference
Yep, it's strange how it feels like that, but that is the best way I can describe it. I wouldn't normally go that many clicks at once for tuning purposes. For the time being, I just wanted to see what the extreme would feel like, a significant change. Right now, I am set to 2 clicks on the lean side from factory position. I haven't actually ran it in this spot yet. This was where I was gonna run it next. I am thinking about running it in the woods again tonight and playing with the clicker some more. The real question will be is what will work best for mx. That is the most important question for me.
I can definitely see how this could work great for alot of people. I could see the woods riders running it a bit on the lean side to be more responsive down low and I could see the dune guys running it on the richer side to ride it WOT.
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I took the R for another spin this evening in the woods by the house. I can definitely say that the engine is producing more power now. What I can't say for sure is if it has something to do with the clams that APT made about this carb giving a power gain or if it is from the fact that this carb's air/fuel mixture is more precisely tuned to the needs of the motor therefore, producing more power. It definitely runs like an uncaged beast when you hammer the throttle. What I can get over is how well the over rev works. I realize the over rev is not where your best power is, but how well it runs in this rpm range vs my old carb is quite noticeable and astounding to me.
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Glad you are happy with it
I think this carb is just as good/if not better than cr ignition
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Glad you are happy with it
I think this carb is just as good/if not better than cr ignition
Agreed^^^. honestly, I think I would favor the carb over the ignition.
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what sizes do they make the cast carbs in?
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what sizes do they make the cast carbs in?
The 38mm is available now, they are working on the 36mm and 40mm cast. They have some billet ones available now in 36mm and 40mm.
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i may have to get a 40mm cast when they come out, the thought of perfect a/f ratio throughout the entire rpm range seems worth the cost of a new carb, but no thanks on the double price of the billet ones lol.
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i may have to get a 40mm cast when they come out, the thought of perfect a/f ratio throughout the entire rpm range seems worth the cost of a new carb, but no thanks on the double price of the billet ones lol.
I agree, and yes it is worth it!
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i contacted the sales dept at apt, i got offered a 40mm billet for $150 off the listed msrp O.o i just may pull the trigger
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i contacted the sales dept at apt, i got offered a 40mm billet for $150 off the listed msrp O.o i just may pull the trigger
Sorry, I should have mentioned that. They have some first generation billet ones that are selling at a good discount. They work just fine, they are just moving towards a more modular design for the new ones.
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Finally got to ride the smart carb on an mx track this weekend. It performed very well. I was very happy with it. It provided plenty of power, it accelerated very well, I'm not sure what else you would ask for. It would allow my to stay a gear higher into the corners alot of times without having to use the clutch and would pull out of them cleanly. I was definitely not used to having to feather the crap out of the corners to keep the engine from bogging. With this carb, the engine didn't seem to care if I was at low rpms, it would pull out of it anyway. I will have to investigate this further.
My first official race of the season is in 2 weeks on a wide open track, and am going to practice on the track next weekend. I think I have going to switch my gears from 14/38 to 14/37 and drop 1-2 clicks on the mixture ratio to boost the bottom end responsiveness and see how I like that. On the other hand, when I go a tad richer, it seems to pull a bit harder the higher the rpm goes. It might be better of me to go a tad richer and pull that extra on the straight aways. I don't really remember how many sharp turns there are on this track. That extra bottom end only seems to help coming out of the tight turns where the rpms drop down some.
It also over revved very well. If I needed a little extra rpm for a short stretch it would give it to me without falling on it face.
Anyway, he is some more feedback for you guys. I have a video of yesterday's race. I will post it soon if it even turned out. It was really more of a practice because the track conditions were so terrible.
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thanks for sharing man! i cant wait to get mine. Looking for it any day now according to Liz at APT!
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Got my next race on this carb coming up tomorrow. Hopefully, I should have some good videos to should how well it is working. That DOES NOT, by any means, mean I will win, lol, just that it is working like the best jetted carb I have ever used.
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Got my next race on this carb coming up tomorrow. Hopefully, I should have some good videos to should how well it is working. That DOES NOT, by any means, mean I will win, lol, just that it is working like the best jetted carb I have ever used.
im glad this worked out. too bad the billet carbs are so expensive. i dont understand why a block of aluminum/CNC time doubles the price.
john
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howd the race go Steve?
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howd the race go Steve?
I'm assuming you are talking to me. Check out this thread.
http://trx250r.org/showthread.php?2876-SE-Quads-Race-2014-Round-1-Bremen-MX-Park-C-Class (http://trx250r.org/showthread.php?2876-SE-Quads-Race-2014-Round-1-Bremen-MX-Park-C-Class)
Ryan
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Thanks for all the info you have posted on the smart carb. I was wondering if it still seems to be a great as initially reported. I have seen threads on the billet carb ,but this is the first I have read about the cast carb. I have a 38 mm air striker on my woods quads, and it's a PITA to try to get the jetting right with the weather around here. I'm definitely thinking of getting the 38 mm cast carb at some point when the hubby gets some extra overtime. The jetting on my Duncan MX motor doesn't seem to nearly as finicky (We never had to mess with the jetting like we do on the 38mm AS), but it has a regular 36 mm carb on it.
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Thanks for all the good info. I think you have sold me on this carb. I really hope ESR starts to sell these one day:)
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Thanks for all the info you have posted on the smart carb. I was wondering if it still seems to be a great as initially reported. I have seen threads on the billet carb ,but this is the first I have read about the cast carb. I have a 38 mm air striker on my woods quads, and it's a PITA to try to get the jetting right with the weather around here. I'm definitely thinking of getting the 38 mm cast carb at some point when the hubby gets some extra overtime. The jetting on my Duncan MX motor doesn't seem to nearly as finicky (We never had to mess with the jetting like we do on the 38mm AS), but it has a regular 36 mm carb on it.
Hey Breezy. Everything has still continued to run the same. The only issue I have had was a little bit ago. When I would be on the gas WFO pounding through the gears, it occasionally would bog. I had a suspicion to two what it was, but called up Corey at APT and asked him. He confirmed what I was thinking. He said that I was draining the fuel bowl and it wasn't filling fast enough. This was due to either needing more fuel level in the float bowl or the fuel cap was not letting enough air through the gas tank. He said that some of the aftermarket plastic check valve that you can buy for the gas tank are highly restrictive and don't allow much air in the tank. I happen to be running one of these. So, I replaced it will some regular black vent hose like factory and raised the fuel level in the carb. Not sure which one was the issue, but good to go now. Other than that, it has been running fantastic. I don't know what to do with myself not having to change jets and needle heights all the time trying to find what runs right! LOL. I have pretty much narrowed down the sweet spot on this low speed find adjustment knob on this Smart Carb and have not been messing with it much anymore. Hope this answers your question.
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Hey Breezy. Everything has still continued to run the same. The only issue I have had was a little bit ago. When I would be on the gas WFO pounding through the gears, it occasionally would bog. I had a suspicion to two what it was, but called up Corey at APT and asked him. He confirmed what I was thinking. He said that I was draining the fuel bowl and it wasn't filling fast enough. This was due to either needing more fuel level in the float bowl or the fuel cap was not letting enough air through the gas tank. He said that some of the aftermarket plastic check valve that you can buy for the gas tank are highly restrictive and don't allow much air in the tank. I happen to be running one of these. So, I replaced it will some regular black vent hose like factory and raised the fuel level in the carb. Not sure which one was the issue, but good to go now. Other than that, it has been running fantastic. I don't know what to do with myself not having to change jets and needle heights all the time trying to find what runs right! LOL. I have pretty much narrowed down the sweet spot on this low speed find adjustment knob on this Smart Carb and have not been messing with it much anymore. Hope this answers your question.
Thanks for the reply :) . I had one of those plastic vent things on my 86 when I bought it. I had seen a thread somewhere about it possibly being too restrictive and just put a piece of vent hose on it. That's great to know that it works well under racing conditions.
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Do you know how clicks out your factory setting was? I got mine on and just around the house it feels very good.
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Corey told me the factory setting was 50-58 clicks from full rich. I am running 53 clicks so far.
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hey guys i pulled my SC off the 500 bike and installed it on the 310. I set it to 50 clicks from full rich. I had my brother start it since i can't kick any bikes over for another month. only ran it for 60 seconds but it sounded good. Im interested in giving this carb a chance on the 310 bike, i was really not happy with the results on the 500. It took my brother about 10 kicks to get the bike started, so i guess we will see how it runs after there is some time on the carb and i play with it more to get it dialed in better.
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hey guys i pulled my SC off the 500 bike and installed it on the 310. I set it to 50 clicks from full rich. I had my brother start it since i can't kick any bikes over for another month. only ran it for 60 seconds but it sounded good. Im interested in giving this carb a chance on the 310 bike, i was really not happy with the results on the 500. It took my brother about 10 kicks to get the bike started, so i guess we will see how it runs after there is some time on the carb and i play with it more to get it dialed in better.
Does it have the needle for the 310 in it or the 500? I remember you saying that they sent you the cr 500 needle, just checking you got the right needle in there. Hope you are healing quick!
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Thanks man! And ya I swapped back over to the 310 needle. I made sure the right one was in there lol. Can't wait to ride it and see how the bike responds with this carb