My '92 flstc "diesel,s/runs on when I shut it off.Ive noticed this when using reg.unleaded but not with Prem.unleaded...I use both depending where Im at .It is not consistent and seems to be when the weather is hot .Anything Ishould be concerned with as far as damage?

 

Yes, I would be concerned. Dieseling is tough on the rods/bearings etc. as it means the engine is "firing" when it is not in the right position to do so. The fuel is being ignited by hot carbon on the piston tops and/or combustion chamber.

Better fuel will help the situation. My bike specifies at least 91 Octane. Regular in most places doesn't cut it. If you can't get premium, maybe carry a small bottle of octane booster.

Also it may be running a bit rich which would cause carbon build up.

Hope this helps

 

Thanks and it makes sense.I have in the past used octane booster .I have only recently noticed it so,I guess the thing to do is carry a bottle of booster in my bag.It does and always run rich.The S&S carb is an old one and I have tinkered with it at times and it just runs better this way.Better than too lean .Gas out in Texas small towns can be pretty crappy.

 

Yes, I hear you. I tend to assume that all stations have premium, because they do around here, but now that you mention it, I remember a couple in South Dakota that only had one pump.

 

my last bike did it . it was a sporty and the shop told me to use high grade gas and to shut it off with the switch and not the key it did work but use high grade gas should fix the problem. if it dont get it to the shop.

 

Throtle plate open too far. I have seen this way too much most times the guys had a low idel due to mis jetting and bumped the curb idle , but if the plate is open too far the bike even after shut down will suck enough air to draw fuel which gets lite in the hot chamber.