Bonneville America Forums Forums Technical Forums General Tech Wants to die

So here’s the situation , after being out of town for 3 months I of course fired her up and headed out . Battery was strong and she fired right up no problem . I did drain bowls before leaving and now she starts and she runs strong until I get her good and warm like maybe 10-20 ml then she starts sputtering and coughing and wants to die at slow speeds or idle . If I keep on the throttle she runs normal and strong . I’m getting conflicting answers to this problem , and I don’t want to just start Willy Nilly try this and try that . One friend says it’s could be coils opening when they get hot , another says let’s tear carbs apart ? When this first happened I thought maybe gas so I drained tank and refueled with fresh and added a little sea foam , did not cure problem ? The guy saying carbs is thinking because I drained bowls that maybe a little gunk is caught in low speed jets but it seems to me it would do it all the time , not just when hot ? I’m open for any ideas to help me save time and money . I’m already going through withdrawal symptoms after being without for what is now 4 months ! Any help would be appreciated 😉😁

Unlikely it's the carbs...given the symptoms you provided, much more likely to be the pickup coil, one of the ignition coils, one of the plug wires, one of the plugs, or CDI.

What diagnostics have you done so far?

If it is only doing it at slow speeds, I'd richen both idle mixture screws to see if the idle smooths out. If not, I'd pull the screws and blow into the ports from the outside. Reinstall and see if that makes any difference.

When it begins to run rough, did you try opening the enrichment circuit to see if it makes any difference. Normally a dirty idle circuit should cause more problems when cold than hot since a richer mixture is usually required during warm up so if the idle gets worse as the engine warms up what I just suggested seems counter intuitive. It's a quick test though.

Another item would be to try unplugging the TPS and running without it. I had a similar situation and traced it back to the throttle position sensor. I unplugged it and never hooked it back up. Bike ran better than ever with no decel popping. You're right about heat potentially causing the coils, specifically the pick up coil to fail when hot. They usually fail open though leaving you with a dead engine or running on one cylinder.

When you say wants to die do you mean it shuts off? Drops one jug? Comes back once cool? If heat related more likely electrical and most likely pick up coil but could be a coil too since they will fail when hot and work cold too. If you are dropping just one jug and it is sporadic most likely CDI. That being said mine still isn't fixed!

To be fair, I haven't worked on mine, been busy with work, installed a new heating oil tank and had to deal with 2 leaks after I filled them about 800 gallons.Just barely seeping so not much loss but don't want any loss. Today corn maze with my grand kids.

Like most of y’all , I’m leaning towards coils or coil related issue ? But having a hard time proving it because of the having to get it hot hot and being by myself it’s hard to do 2 things at once 😏 my friend the mechanic really wants to get the carbs out and check them first and the only other mech I trust is to far away for me to get it there . Oh whoa is me . First real problem I’ve had since new in 02 so I guess I can’t complain to much .

Can swap the coil wires from one side to the other and see if the problem changes sides if you are only losing one side. That is the power wires and plug wires. If it changes sides it indicates a bad coil if the same side malfunctions it is probably the module. If it dies all together when hot probably the pick up coil. That test indicated to me on mine the module but didn't fix my issue. Won't hurt to clean and reset the carbs. Adjust the mixture properly don't guess. The carbs are simple and doesn't take long to go through them for cleaning purposes unless you do find a clogged circuit. Then it depends on what's clogged.

Same with my issue, no real problems since 05, I think my problem was caused from letting it sit when my wrist was broken, sat over a year.

A late response and I hope you've already resolved your issue, but I had a similar issue. I gave up but my mechanic traced it to cracked insulators on the spark plugs. Not visible under inspection but that's what it was. New plugs were the solution.