I'm having fuel issues with my 94 heritage. I have looked through the forums and found many ideas and tried many things with the same results. I will try and give as much info as I can to help identify the problem or cut some of the trouble shooting down.

I had my Evo rebuilt somewhere around 5-6 thousand miles ago buy Master bike builder Kendall Johnson in Winston Salem, NC.

I recently replaced most of my electrical system on the bike after my voltage regulator going bad and my circuit breaker being wired up wrong(my bad). after replacing most of the electrical the bike ran good for several weeks, then would shut off while riding if i released the throttle to fast to shift or to break. I wouldn't start back up from dropping the clutch, I had to let it completely shut down till the oil light came on then it would start back up. After trouble shooting this for about a month and getting frustrated I decided it was time for a carb rebuild. I have a stock evo engine with the keihin cv40 carb.

I purchased the rebuild/seals kit and proceeded. I did not replace or change the factory jets or try to modify it in any way as I plan to give this bike to my son next year when he turns 17.

The rebuild was fairly simple as I have been turning wrenches for over 20 years. I disassembled the carb and soaked it in the industrial carb cleaner that is in the 1 gallon paint can. Washed it with water imediatly after and dried it off and used an air compressor to force air through the ports. I used a flashlight and held it to the main and pilot air jets and could see the light looking down the main and pilot jet seats. I replaced the factory Pilot(idle) mixture screw with the cv performance EZ-Just screw with new spring, washer and o-ring. Inspected the slide and diaphragm and couldn't find any defects. replaced the diaphragm, spring and o-ring on the accelerator pump. Adjusted new float and replaced float valve. replaced the float bowl seal.

When putting the main jet back in I over tightened and bent the emulsion tube. I went to the stealership and ordered another one. Inspected the needle guide that sits above the emulsion tube and it seamed fine. Put the rest of the carb back together with out any other visible issues. Installed the carb back on the bike. turned the fuel on allowing the float bowl to fill. pumped the throttle a couple of time and can see fuel shooting through the accelerator pump nozzel. telling me it was getting fuel.

Started the bike with choke/enrichment on, and let it warm up. closed the choke and idled great. all smiles so far.

As soon as i move the throttle any the engine completely shuts off. No stumble or hesitation just shuts off. I have adjusted the pilot mixture screw to about every position I can and doesn't seem to make any difference, not even a change to the idle speed. Figuring I have some sort of vacuum leak I replace the intake to head seals, carb to intake seal, tank to carb fuel line, and the VOEC vacumm line. I checked to make sure the VOEC was working by both squezzing the vacuum line and unpluging the electrical connector. Both of which changed the idle. Assembled everything again with the new seals with no change. Idles great but shuts off with any throttle movement.

I discovered that if I opened the choke/enrichment the bike would run and and would climb to higher RPM's but wouldn't be smooth. I can also use My hand to cover about 95% of the carb face denying it of air and could achieve the same effect as leaving the choke opened. When using either method i can watch the slide move up like its suppose to. When throttling the engine either way it will spit and or pop and sometimes I see blue flames from the factory exhaust.

I have taken the carb back off and torn it down several times looking for missed steps or trash. Read through many forum post about carb issues looking for ideas. I replaced the air filter and tried running the bike with and without the air breather assembly, everything is factory oem.

I have checked and replaced the spark plugs, rechecked the ignition system ensuring that it was sending fire to the plugs. adjusted the float levels both ways to get a lean and rich environment with no fix.

I can spray wd-40 or starting fluid around the intake seals with no change in the idle.

Last night after disassembling the carb again and letting it sit in the cleaner over night then rinsing in boiling hot water and blowing through the ports again the air compressor again, I re-installed it on the bike with no love.

I did however notice that with the air cleaner off I could hold my finger over the Pilot air jet and it would slow the idle and shut off. If I hold my finger over the main air jet it makes no difference at idle(knowing it shouldn't since idle uses the pilot jet, and or starter/enrichment jet), also didnt make any changes with the choke/enrichment open achieving higher RPM's with the throttle.

This makes me think that There is a problem with my main jet setup. the vacuum from the running engine and with the slide open its still only getting very little fuel through the needle guide. sometimes at idle i can see small amounts of fuel running across the inside/bottom of the carb sliding under the butterfly.

This has been a long explanation of my problem but wanted to give full understanding of what my issue is and what I have tried.

Any ideas or suggestions are welcomed. A friend of mine has a S&S carb on his 98 fatboy and said we could try it on my bike to make sure its a carb issue. The only thing I haven't had access to is a known good carb to eliminate any other possible complication.

Sorry for the long explanation, any help would be great.

 

Did your emulsion replacement emulsion tube have the same amount of holes in the side of it as the old one ?

 

got the needle jet in correct?

 

Sounds like your floats sticking.

 

gsxrboy, yes new tube has same holes in it.

Ranger, checked and double checked the float and float valve. Have used 2 of each in all combinations.

jrgreene, you might be on to something, It is currently in in the right direction, however after checking and trying it wont fit upside down, the other end is slightly flared. I don't think its suppose to be that way and might have damaged it when I over tightened the first emulsion tube. I am going to the local stealership in the AM to see if they have one in stock. Thank you for the good pictures of both sides. I will update tomorrow on the results.

 

Picked up a new needle jet today, installed properly without over tightening and that fixed the problem. Bike is running great again.

Thanks again jrgreene.

 

glad it fixed it..i had one eat my lunch a long time ago..now its one of the first checks i make