Originally Posted by BM3flitedog
I am having a strange problem. I have a chopper with a 124 inch S&S. I just reciently performed some changes on the bike including a vance and hines exhaust, new spark plugs and 8mm ignition wires. My problem is now that the bike is all back together the front cylinder is getting very hot almost immediatly after I start the bike and is turning the plug black. The rear cylinder seems to be running normal. The bike sounds like it is running great though. Please Help!
What KKrider said....
Is the plug a dry, sooty black, or wet and oily? If it's dry, go to the next paragraph. If it's wet, call the builder of the engine. It'll need some top end repairs.
Check for an intake leak. Spray some WD40 (use the red nozzle) around the flanges (carb and head ends) while it's running and you will hear the rpm change slightly if there's a leak. My guess is that the rear cylinder is leaking causing the front cylinder to run richer and hotter.
The next, and most important step, is to put it on a dyno to get it tuned properly with an AFR gauge. That's the only
way to get the mixture correct across the whole rpm range. This is something that must be done whenever you change the induction or exhaust systems.
Another thing... are you using the S&S carb? If you are, do not use the enricher (choke)!! You'll be fouling plugs regularly if you use it too much. I only use mine if it's less than 20 deg. F. outside, and even then for no more than 30 seconds. That's about the only flaw with the S&S carbs. Other than that, they perform great!