My Evo is very sensitive to spark plug gap. .040"= misfire and hard starting,runs on one cyl. for the first 10-15 seconds. .038"= perfect start and no missing. Might be worth a try.

 

I learned the hard way on cooking ignitions. My sled would drop a cylinder, shut off, all kinds of stuff. Would put a new ignition in and happen again. Well....when all said and done, the culprit was the VOES switch. The VOES was not operating, end result the motor does not run as efficient, advance the timing and run hot and ultimately cooks the electronics...... Check that VOES..

 

i agree its either the ignition or and intake leak had same problem on my 86 FXR and yes it did mifire and run on only one cylinder .i checked intake with carb cleaner and found back jugg was leaking bad and no it wasnt firing correctly it was only running on front.took off manifold and 1/2 the gasket was gone .changed it and it runs perfect now matter of fact it runns better now than the day i got it . just press the start button and she is purring never did that before always had to choke it repeatedly so the moral to my story was it was the intake gasket misssed on idle but would 1/2 *** ru as i reved it !!!

 

run a race bike with programmable ign no cover

 

+1 very sensitive to gap

 

thanks for all the help i will ckeck all that was suggested...........

 

I had a sportster once with an intake leak and it ran like crap and wouldn't idle. I fixed it and it was smooth.

Also, I run the Screaming Eagle Ignition on my 91 FLSTC and it's great. I would recommend it.

 

i'm running a Daytona Twin tech ignition and never once has faikled me in over 5 yrs my opinion its top of the line and resonable priced

 

That's how i found my VOES switch problem. I am running the Daytona Twin tech ignition now, instead of the crane Hi 4. The Daytona ignition has a VOES light to show you it's working mine did not initially light up and found the VOES was not operating.

 

Interested in how this turns out. My 1995 ultra 80 ci. evo started doing the back fire, pop, hick up, stall - under aceleration

Engine seemed to be getting hot for me though.