Author Topic: APT 40mm Billet Smart Carb mounted on a 431 Puma. With important mounting notes. (Read 46067 times)

udontknowme · « **Reply #15 on:** November 16, 2014, 01:35:57 PM »

heres my take on it. if your not concearned with gas mileage or ride from sealevel to 10,000' in the same day (which is a couple benefits the carb is 'supposed' to have ), i would throw that smartcarb in the bush and use a keihin, or even a mikuni. if gas mileage is a concearn, seems like maybe this sport isnt for you. youve already got a ton of money invested in the bike, whats a extra $5 in gas each time you ride.

i get the feeling your chasing some benefits that may not even exist. the people at smartcarb made alot of claims, other than seat of the pants testimonials from average customers ( which are anything but scientific or concrete), im not sure any of the claims have been legitimatly substantiated. i know theres people still having problems with the smartcarb. some have even thrown in the towel and sold it or got a refund

cant recall his name but the other guy on this site using the smart carb made a video, honestly it didnt sound like his was running all that well either

ive seen other vids were guys are jumping for joy at how well the carb seems to work, but yet the vid says otherwise. one guy installed one on a snowbike and raved how good it worked, yet the rpm was hanging like mad everytime he let off the throttle. this tells me the guy has blinders on and is just another victim of the hype

Jerry Hall · « **Reply #16 on:** November 16, 2014, 11:38:03 PM »

Quote from: udontknowme;46078

heres my take on it. if your not concearned with gas mileage or ride from sealevel to 10,000' in the same day (which is a couple benefits the carb is 'supposed' to have ), i would throw that smartcarb in the bush and use a keihin, or even a mikuni. if gas mileage is a concearn, seems like maybe this sport isnt for you. youve already got a ton of money invested in the bike, whats a extra $5 in gas each time you ride.

i get the feeling your chasing some benefits that may not even exist. the people at smartcarb made alot of claims, other than seat of the pants testimonials from average customers ( which are anything but scientific or concrete), im not sure any of the claims have been legitimatly substantiated. i know theres people still having problems with the smartcarb. some have even thrown in the towel and sold it or got a refund

cant recall his name but the other guy on this site using the smart carb made a video, honestly it didnt sound like his was running all that well either

ive seen other vids were guys are jumping for joy at how well the carb seems to work, but yet the vid says otherwise. one guy installed one on a snowbike and raved how good it worked, yet the rpm was hanging like mad everytime he let off the throttle. this tells me the guy has blinders on and is just another victim of the hype

Every carb that I have tried to tune that was designed by the Edmonds since the Lake Injector (Lectron) has just been a Lectron with different lip stick. Time will tell if the Smart Carb is also a Lectron with different lip stick and has the same limited tuning capabilities as it's 3 ancestors.

udontknowme · « **Reply #17 on:** November 17, 2014, 01:27:52 AM »

well if a guy insists on using one of these jetless carbs, it seems like the lectron might be the better choice at this stage in the game. a year from now the smartcarb might be superior but it sure doesnt seem like the way to go as of now

some of these guys that buy the smart carb really piss me off. they say how good it works but in the same sentence they say its either to lean and down on power or its spooging oil all over. either it works good or it dont. simple as that. like i said before, i think most of these goons that buy the smartcarb have blinders and refuse to recognise the problems for what they are. like this moron that just wrote this today on another site. clearly hes having issues but goes on to say even with all the trouble its still better than a keihin

?? what the hells wrong with these people . no offense to anyone here as im mostly refering to all the other people from different sites. far as i know i havent seen anyone around here mention their smartcarb troubles and in the same breath also proclaim how much better it is than keihin

Hey Corey you make that tuning video yet?

I like my smartcarb but honestly I can't figure out how to set the needle perfectly. It just doesn't give me the feedback I'm used to getting from a stock carb. When I lean it out a bunch it is down on power, when I richen it a bunch I start getting spooge but I can't seem to find the middle. Always have to blip it a little to keep it running at idle.

The bike definitely rips with the smartcarb and it's a big improvement over the keihin but I'd like to get it running perfect

Jerry Hall · « **Reply #18 on:** November 17, 2014, 01:35:03 AM »

Quote from: Pumashine;46037

The picture of the top of the piston is a perfect example of what detonation will do to the top of the piston.

Notice the etching or sand blasted band that starts next to the bore. The band is about 3 mm to 5 mm wide and starts at about 8 o'clock and stops at about the 4 o'clock position. The destructive forces of detonation have actually removed metal from the top of the piston in this band that looks sand blasted.

If you look closely at the head, you will also see the same band of destruction in the outer edges of the head.

A close inspection of the o-ring that is next to the bore and the inside of the o-ring (closest to the bore) will usually show etching and or erosion of the rubber. Mild detonation over a longer period of time will gradually erode the inner o-ring to the point it can no longer seal. Severe detonation over a period of 15 seconds or less will create the piston we are looking at, lead to severe piston overheating and result in a seized piston with possibly mild 0-ring erosion along it's inner circumference. Increasing the distance from the bore to the o-ring grove will help protect the 0-rings from detonation. If I had the option of redesigning the cylinder, I would move the studs and o-ring groves at least another 3 to 4 mm further from the bore.

The destructive forces from detonation will eat away the top edges of the piston, the edge of the cylinder where the bore and head gasket surface intersect, the outer edges of the squish band as well as the o-ring and head gasket if it has one. Detonation is also hard on connecting rod bearings, main bearings, bearing pockets and causes the engine cases to crack through the middle of the bearing pockets.

The piston crown has experienced intense heat. The heat has been so intense that it has consumed all of the carbon from the crown of the piston. The exhaust temperature has also been excessively high, indicated by the edged of the piston being burned away next to the exhaust port. Wiseco piston crowns that experience this level of temperature will usually “sag” or “droop” between the center of the piston and the exhaust side of the piston. If you look at the underside of the piston you will probably see dark ash deposits. Look at and feel the top of the piston to see if the crown has a spot that has sagged.

In the next discussion we will talk more about what causes detonation and what can be done to eliminate it.

udontknowme · « **Reply #19 on:** November 17, 2014, 01:45:49 AM »

so the million dollar question. can a foaming carb cause all this destruction or is there several things at fault here. i have hard time believing a foamed float bowl caused all this by itself. we know nothing about the engine setup. comp ratio, timing, pipe, head geometry, fuel, oil. we know nothing. so it seems impossible to make a conclusion what happened

toydoc · « **Reply #20 on:** November 17, 2014, 03:35:31 AM »

For sure foaming can do this. If you run it on a dyno with fuel flow reading, you will see fuel flow go erratic then no flow under WOT. When you see fuel flow bounce, kill the motor, check to see if its grounding out (just as he did). If it looks good, move the carb back / add intake boot. Retest, if still a issue add weight to the bell mouth (epoxy wheel weights to clamp or bowl). Sometimes it's not just foam, the vibration will act as a Hz frequency on the needle and seat, like a impact on a nut. Then your into fluid dampers and moving rpm around

rsss396 · « **Reply #21 on:** November 17, 2014, 06:38:29 AM »

My cr500 based drag bike has vibrated bad enough to lift Lectrons adjustable slide needle and turn it, which then leans the motor out because the flat side of the needle no longer faces the motor.
For those that do not know, if the flat side does not face the motor less fuel is pulled from the carb bowl. The flat side on the needle creates a low pressure area when air rushes by thus pulling more fuel than your typical round style needle found on a kiehin or mikuni

Jerry Hall · « **Reply #22 on:** November 17, 2014, 10:31:18 AM »

Quote from: udontknowme;46110

so the million dollar question. can a foaming carb cause all this destruction or is there several things at fault here. i have hard time believing a foamed float bowl caused all this by itself. we know nothing about the engine setup. comp ratio, timing, pipe, head geometry, fuel, oil. we know nothing. so it seems impossible to make a conclusion what happened

ll

Testing, testing, testing, testing and using the process of elimination can only answer this question. A fully instrumented bike with data loggers while testing riding in the real world, is the only way I have been able to solve these types of problems when doing consulting for engine manufactures.

Sometimes all that needs to be done is change the riding style (the throttle position and RPM) to that for which the engine was designed. Two stroke engines that have been developed to medium to high levels of power output should not be used for just cruising around because of detonation related issues due to poor scavenging. This is the main reason manufactures pulled the plug on large two stroke street bikes. It was not because of emissions like most of the world believes.

rsss396 · « **Reply #23 on:** November 17, 2014, 12:54:33 PM »

if the pipe was changed it could make the problem better or maybe worse, allot of dynamics going on, but IMO I would add a simple power jet to this motor but thats just me.

mx250r91 · « **Reply #24 on:** November 17, 2014, 06:20:34 PM »

Looks like Lectron runs power jets on their carbs.

http://www.lectronfuelsystems.com/carburetor/

I wonder if one could be adapted to the smart carb?

This is from their FAQ:

"Should I have a power jet carburetor or not?

This is a must for a two stroke engine. We prefer to have them on all types of engines two or four stroke.
The power jet carburetor can give you a wider range on tuning and also helps you fine tune top end power on all types of engines."

"What does the power jet do for tuning?

The power jet is for high speed tuning only. The power will kick in about 3/4 from top RPM First get the motor running good at idle and mid-range then work on the power jet.
The power jet will not effect the tuning of idle, mid-range, or response on the carburetor."

rablack21 · « **Reply #25 on:** November 17, 2014, 08:22:08 PM »

The smart carb essentially already has a power jet. The pressurized fuel bowl does the same thing. There is a tunnel that connects the air side of the carb bell to the fuel bowl. When at wot when the signal from the engine is at its strongest, the tunnel creates a huge pressure that draws even more fuel into the air stream, just like a power jet does. People keep comparing these to Lectrons but their only similarity is that they are both single circuit flat side carbs. The similarity stops there. How they operate are very different. Corey will speak more about this shortly.

SmartCarb · « **Reply #26 on:** November 18, 2014, 08:07:15 PM »

Quote from: Pumashine;46037

Started running the 40mm billet smart carb back in February 2014. The loaner carb had float bowl issues. After resetting the float heights it was not refilling the bowl quick enough. It would like just die at full throttle. Low and behold the tech at APT says it is very touchy setting the float height while still maintaining refill flow rate. The carb was real lean compared to a normal carb on the bottom end. Seemed to breath fresh air into riding in first and second gear. This prompted me into getting a 40mm billet for myself. Put her on and got her started. Seemed to be just a tad to lean so I proceeded to richen the clicker every couple hours fearing I was going to seize her up at WOT. From 1/2 to full throttle there was a stumbling spot. I contacted APT and requested a richer Fuel Metering Rod or FMR.

Received a new 76 FMR a couple weeks later and put it in to replace the leaner 78 FMR. I did not write down how many clicks I had the clicker set at. I was instructed to get the bike started going about 50 to 60 clicks from full rich. Then keep going leaner until the idle started to get angry. Like when your bike is running out of gas. It will rev up for awhile and then come back down a little and repeat. Once the idle gets a little angry you then set it 2-3 clicks richer until you have a perfect idle. Once you get a perfect idle you can then drop the idle speed down to where you like it at.

I was really excited now the FMR was richer and I hope to get the stumbling out of the 1/2 throttle area. Went out for the usual dune ride at Winchester bay. Was great 0 to 1/2 throttle. Was stumbling still at 1/2 throttle. When full throttle was achieved she ran great. I was still not sure what was causing her to stumble. Rode the rest of the day and figured I would ask questions on Monday. Kyle Burns put it this way summarizing where the clicker works.

So I went 3 clicks richer the next weekend. I get to the dunes and go to start her up and she just won't start. I notice gas dripping out of the header pipe. Had someone pull start me. Had to get pulled around the parking lot but would not start until I let off the throttle completely and just barely fired. It gets going and I go for another dune ride. After coming back and having a beer and refueling I go to start up again. Won't start. So I do the pull start thing again. Same results, like it was flooded. Went for another ride and same scenario. Was making chirping noises under full throttle. Like metal on metal as the train goes by. Would not start again after cooling down in the parking lot. Seemed strange if you stopped out on the dunes for a minute she would start right back up when hot. Loaded her back up and went home.

The next week I took the seat off and double checked the boot was sealing around the intake manifold. It seemed a little loose when I checked it out riding the weekend before and tightened the clamp. My thoughts were maybe it was loose and moved on me. After loosening and trying to move the carb forward I tightened it back up and turned 3 clicks richer, it actually started. Thought maybe it would not start due to extreme lean condition as stated in the manual.

Tried again the next weekend. Again the bike won't start so I got a pull start. Each time coming back for more fuel I just let her idle instead of hitting the kill switch. Just turned the idle up a bit. I had noticed after setting my idle at home I had to turn it up after getting to the dunes the last couple weekends. I went and gave her 3 clicks richer and was going to go do a plug check. As I got to 1/2 throttle just to about 3/4 open the piston froze up. SOB, did I go 3 clicks the wrong way? I got off the bike and started pushing her back to the parking lot. A guy rides up and asks me if I am out of gas. I look at him and say "I Wish" As I was sitting there waiting I kicked and the piston broke loose. Zero compression.

I'm like :wtf?:

APT says if the carb is hitting the frame it vibrates the carb not allowing it to atomize the fuel correctly. This week Kyle or Ryan was saying this creates a lean condition. So I went and took pics to show no frame touching.

Measuring from the carb to the intake is 3/4" in this pic
I then removed the boot and set it back to 3/4"

Now you can see the carb is touching the intake on the far side. This indicates to me that the carb touching the motor may do the same thing as the carb touching the frame. Even though no one mentioned this as a possibility. Heres a better pic so you can see how hard it is touching. The black sharpie line is where the boot was on the intake. It was up tight against the carb.

The plug is tan at piston freeze. I took this pic as I was taking the cylinder off.

So the whole time starting February until now (November) the carb has been experiencing the lean condition intermittently? (every 5 minutes) I am guessing. Seems the aluminum has been eaten away on the exhaust side of the piston.

From looking at your pictures it appears that mixture values were fairly close to optimum as indicated by the plug. If this is indeed the plug as you removed it from the seized engine, (I'm not implying that I don't believe you) the mixtures certainly weren't lean enough to cause the localized overheating of your piston and ultimate seizure that occurred. I believe the evidence would indicate that the front spigot of the carburetor was hard touching the intake manifold enough to cause severe shaking of the carb and aeration of the fuel in the bowl enough to lean it down to critical conditions in the mid to top end. I would also be inclinded to say that this was likely the trouble all along and the richer metering rod is probably not necessary. Furthermore this was also the cause of the intermittent flooding issues that you were dealing with prior to the seizure. After your rebuild and necessary clearancing of the manifold I would also inspect your SC to see if any damage has occured the the fuel inlet needle/seat.

SmartCarb · « **Reply #27 on:** November 18, 2014, 08:32:46 PM »

Quote from: udontknowme;46108

well if a guy insists on using one of these jetless carbs, it seems like the lectron might be the better choice at this stage in the game. a year from now the smartcarb might be superior but it sure doesnt seem like the way to go as of now

some of these guys that buy the smart carb really piss me off. they say how good it works but in the same sentence they say its either to lean and down on power or its spooging oil all over. either it works good or it dont. simple as that. like i said before, i think most of these goons that buy the smartcarb have blinders and refuse to recognise the problems for what they are. like this moron that just wrote this today on another site. clearly hes having issues but goes on to say even with all the trouble its still better than a keihin ?? what the hells wrong with these people . no offense to anyone here as im mostly refering to all the other people from different sites. far as i know i havent seen anyone around here mention their smartcarb troubles and in the same breath also proclaim how much better it is than keihin

Hey Corey you make that tuning video yet?

I like my smartcarb but honestly I can't figure out how to set the needle perfectly. It just doesn't give me the feedback I'm used to getting from a stock carb. When I lean it out a bunch it is down on power, when I richen it a bunch I start getting spooge but I can't seem to find the middle. Always have to blip it a little to keep it running at idle.

The bike definitely rips with the smartcarb and it's a big improvement over the keihin but I'd like to get it running perfect

Forums were made for the squeaky wheel. Most likely people will not post until they are having an issue or out of fairness post to make people aware of the issues they are having hoping to find a fix. Interesting indeed that even with a nagging issue they haven't yet figured out they are still willing to admit it's better than what they had. What you don't hear on the forums is the 95%+ success that we actually have in the field with all carburetors sold or the people that later found out it was an issue with their bike and that they had simply been tuning around a problem for years with their multiple circuit Keihin. The third party validations, testimonies of dramatic increases in fuel economy and flawless bottom to top performance, dyno video's from DirtRider magazine, articles in Endurocult and quite a few european magazines that aren't necessarily read in the states, on road US and european emissions certifications without the use of precious metal catalysts. It's all out there and the realities of this fuel system will become more evident with time. It's funny you mention videos though, I've made a living out of tuning two strokes and designing two stroke engine products and I listen to these videos and can't tell anything about how the engine is actually running based on crappy phone camera microphone. At least not to the point of calling a person a moron, perhaps you have a better ear than I.

Pumashine · « **Reply #28 on:** November 18, 2014, 08:43:16 PM »

Quote from: SmartCarb;46204

Furthermore this was also the cause of the intermittent flooding issues that you were dealing with prior to the seizure.

Thankyou for confirming the theory my problem was the engine vibration. The cause of flooding and not starting is caused by what? I just do not understand what you are saying. Are you saying the 76 FMR is too rich? Please don't mind the members on this forum. Some like to say I told you so. I agree your carb is amazing. I just believe the vibration has caused the intermittent lean condition and in time the piston ultimately failed. I have ordered a rubber intake manifold to get away from the intake manifold hitting the carb.

SmartCarb · « **Reply #29 on:** November 18, 2014, 09:18:57 PM »

All that shaking will also upset the fuel inlet needle and seat. In your case I believe it caused the needle/seat to begin leaking intermittantly leading to flooding and hard starting.