I have a 2003 Sportster 883C and I put on Scorpion chrome headbolt covers. When I start the bike, it's only running on 1 cylinder, then there's a loud backfire out the exhaust. I put the cover on the rear cylinder only, and the bike starts and runs fine. I put the cover on the front cylinder, and it starts misfiring and backfiring. As soon as I take both covers off the bike, everything is back to normal and running fine. Has anyone run into this? It's pretty clear the spark is getting absorbed by the cover and not going into the plug. How do I fix this and still be able to use the chrome covers? I have the stock wires on it too.

 

Are the wires in good condition? No splits, no cracks? You didn't mention how many miles you have on it and if/when they were changed. Could be as simple as worn out wires with a degraded jacket.

The covers don't pinch the wires do they?

It sounds like you are right on. Apparently something is grounding that front plug wire against the cover.

 

I would say you have dry rotted wires or at least a boot and the spark is going to ground...

You found the answer yourself... it the cylinder dies with the cover on and it don't with it off... that tells you something... don't it???

Charlie D.

 

Pretty typical of those covers. You need to work the plug boot in them real good to stop the spark from jumping to the head. I got tired of the hassel and chucked mine in the trash.

 

The wires are stock, and they have about 4000 miles on them. I may buy a new set of wires and give it another go, and if it still messes up, I'll just re-ebay them.

I knew the problem, I just didn't know the solution (other then not using the covers).

 

if you reebay them i can hook it up on some headbolt spikes instead!

 

Thanks, but I'm pretty conservative and my bike doesn't look custom enough to pull that off. If you have regular/less spikey ones, I'll take those!

 

JRK- How much for the black ones, me likes.

 

PM me guys... we can work it out here is a pick of the black on my bike
(sorry crap pic)

steve i am sure we can do something a bit less agressive

 

Those Scorpion things are a pain in the *** unless you modify them. I used one of those step drills and bored out the center hole so the plug boot would go throw the chrome.
I have these on two differant bike with this modification and they work perfect.