Can anyone tell me what the cause of "dieseling" is on my 97 Softail Custom? It only does it now and then but the motor will actually run backwards after killing it with the run switch.

Thanks for your input in advance!

 

1. Intake leaks
2. Idle too fast
3. Engine runs too hot
4. Bad fuel
5. Carbon build up on valves
6. Bad plugs
7. Carburetor leaks

 

Detonation/pinging creating hot spots leading to the dieseling. Also can be caused by carbon deposits getting hot as said above. It is residual fuel buring after the ignition shuts down.

Some say that Seafoam is good on carbon deposits. I know that it will cause your bike to smoke like a son of a gun until it is burned off.

 

Ditto what's said above. Good idea to address it if it becomes more than a now and then thing.

 

Switch do a better gas or hi test 1st.

 

is it bad on a engine for it to diesel?

 

Timing too far advanced, fuel / air mixture too lean, low octane fuel are all causes of dieseling.