Hello all and thanks for all the great help this forum gives. I have an 94 flhtc that has started to run very badly, It sounds as if it is only running on one cylinder and I believe it is coming from the rear cylinder cause when idleing it has an occasional pop from that cylinder as if it is firing a small amount of unburnt fuel on the exuast stroke, the popping does clear up a bit when warmed up. I have tryed everything I can do and think of to solve this with no luck. stock evo with ev13 cam stage 1 air true duals, rush slipons with 2 1/4 baffles, ram jet intake w/mikuni 42, 25 pilot, 160 main 60 pump nozzle, s/e module and coil. things I have tryed, new intake gaskets all three very carefully installed, had new timing sensor plate installed that, new plugs, cleaned and inspected carb thoroughly, checked fire at plugs with timing light, rear plug fire's more rapid then the front I guess this is normal? Checked comp and both cylinders at 140 steady vaccum at 7 to 8 in. Tryed setting timing at differant degrees, voes working properly tryed good known working coil, fresh fuel, checked all wiring for any broken or chafing. All this with no good results. Then I thought I would put my S/E coil back on and when I pulled the plug wire's off the coil I noticed the wire goin to the rear cylinder was not right, the fiber core had cam out from under the metal connector and I figured hell yes this is got to be it, with further examination looking at the coil trminal where this wire was it was black inside from arcing. So I put on new wires and coil fired it up same result So i'm wondering if this arcing wire in the coil could screwup the module and maybe make it fire at the wrong time? Help please I'm lost at what to do next.

 

Try a lek down test done with the engine warm. Was the compression done with the engine warm??? Was the throttle held open?? 140 isn't bad but is on the low side with an EV-13. Have you checked your pushrods for proper adjustment??? Please check these and get back to us. This problem can and will be solved!!!!!

 

Hyd lifters in good condition ? Rollers off the lifters running concentric ? Try another good ign mod How many miles on this beast?

 

Have not tried leak down test and engine was at normal operating temp when comp test was done with throttle wide open, Also have checked pushrod adjustment which was my first check. Lifters and pushrods only have 1000 miles on them so they are all good. I hate to purchace a new module if this will not fix it. I figure if a module goes bad it wouldn't even run. I will try the leak down and post results. Forgot to add that this motor has 44000 on it but only 2300 on top end rebuild not for sure whats on the module it was installed by previous owner.

 

Ignition module troubles on the EVO can be wacky.

Charring in the coil means there was not good contact between the wire and the contact deep inside the coil, I've seen that increase in resistance damage a coil. I see where you've repaired all that too.

Mine ran perfectly when running. Give it a little warm up time on the road and it stopped sparking. Pull over let it cool and vroom back down the road. The issue got worse the more parts I threw at it. I was going from an occasional stumble to not being able to go more than 5 or 6 minutes warming in the drive and the spark stopped.

Now if you have upgraded any ignition components, like moving to a non OEM ignition system this could be the issue of one cylinder firing correctly and missing on the other cylinder. That could be in the Ignition module functions.

Also the process of elimination leads you to the Ignition module as the last component that has not been replaced.

Call around and locate a used, but still good module to sub into the system and give it try. Worked for my situation.

 

I always go through as much checking as I can before I spend the $$ for a module.
What did you do JUST before this started? How did it start?? On the road, or after a fire up? Was the battery dead, what was the "starter thread"?????
Check your grounds, no better, reinstall your grounds.
Perhaps if the leak down test is good- a weak or broken valve spring???
Valve hangin up in the guide????
(The '90 Electra Glide I just purchased has a issue like that. A H.D. shop the P.O. sent the motor to for a top end rebuild replaced the guides. Like 3000 miles later, he had to take it yet another shop-1 cyl. dropped. (weirder yet) They had to replace the guides and valves???) so ShEEt happens.
I often wondered if an older automotive isloscope (sp) with the clip on pick ups, would show the ignition system in operation????
Stay positive!
Joe
If it were easy, there'd be no "horror" stories to tell with our beer!

 

There are a lot of shops out there that do "top end" jobs that do not have the equipment. So what you get is a new set of seals and the valves lapped, then out the door. unfortunately the customers very rarely finds out about it.We have a lot of money in tools to work on these bikes.

 

+1 on the grounds, id check resistance on the plug wires too.

 

Thanks for all the replies I will consider all and will go for the leak down test first but will have to be in the morning as the wife thinks we need to do other things tonight not sure what could be more important LOL!! Will definetly post results as soon as I know. Thanks and keep the disccusion going. Todd

 

alright the wife had a change of heart and let me spend some time with the old girl and was able to do leak test and I find nothing wrong here. rear cylinder has 15% and front with 13% loss and all is through cylinders. I think I can live with these numbers. I feel like it is mechanicaly sound.
Thoughts?