I have an 83 harley fxrs, with daytona twin tec 1005 electronic ignition, two single fire accel coils, MSD spark plug wires, drag special spark plugs ( kinda old) super E carb, dual plug heads. I'm currently trying to tune my carb and while doing so ive noticed my rear cylinder is hotter then the front. The rear is when getting on the throttle puffs black smoke. Its not the rings because the engine was rebuilt. As in i cant even grab the rear exhaust pipe without getting burnt but i can hold onto the front no problem. I know the rear cylinder is firing because i can fell the exhaust out of the pipes. Why is the rear running hotter?

 

I am curious as to if the front cylinder is firing because you said you can hold onto the front exhaust no problem without getting burned while the rear pipe would burn you. Just because air comes out the pipe doesn't necessarily mean that cylinder is firing.

 

I'm starting to think so to. I know its not the coils. Because I'm using two accel single fire coils. So one coil firrs both front and rear, then the second coil does the same so if one coil fails it will still fire. I know its not the head gasket because it was just replaced with a MLS one .40 thick. The only thing i haven't changed was the spark plugs.

 

Timed to the rear vs front cylinder??? Happens all the time! Note that retarded timing Always makes excessive heat also... If you touch my front pipe after just a little while...you will be burned... Note; The rear cylinder on a Harley generally runs cooler... so yea, something is wrong!!!

 

For timing i aligned all the marks in the cam chest like they are suppose to be, then i followed the instructions for the daytona twin tec 1005 for timing which is based off the front cylinder being at tdc if i remember it was the vertical line for tdc.

 

swap the coils and see if the problem follows

 

I can't swap the coils because the way they are wired. I attached a picture i know its ugly but im waiting on a new wiring harness, and design and make a side coils bracket mount. As u can see one coil controls one side front and back and the other controls the other. I got the spark plug out of the front cylinder and completely fouled, smells and wet of gas and completely black, i took the rear out and they look bad but they don't stink like gas.

 

^^ Dual fire??? Put it on Single fire...tho as wired ...it ain't the coil/s... BTW...When ya Zap yer Nuts, you will tidy that mess up...

 

Those are accel single fire coils, using two since i have dual plug heads.

 

I see what they are... You are wired for Dual Fire...wasted spark...Single fire is One coil to each Cylinder...Not each coil running to Both cylinders....