I was hoping to get some thoughts on my current carb setup. I recently bought a 2004 Heritage that had a stage 1 setup (K&N filter and some cheap drag pipes with short baffles). The plugs looked great with a nice brownish black color, the bike ran good (no coughing) but didn’t have a ton of power. I always run straight pipes so I took the baffles out and the bike started running like a dog (low power, occasional coughing, stalling, etc). I checked the plugs and they were now bright white; the only mod at this point was removing the baffles. I figured I’d tear the carb apart to rebuild it (just to be safe) and check the jetting. From my research it appears to have the correct jets in it already (48 Slow and 190 Main) but it had the stock needle still and it wasn’t shimmed. Instead of shimming the stock needle I decided to buy and use a new 1988 Sportster needle but didn’t shim it (this is what I read to do). I initially set the mixture about 2.5 turns out, the bike immediately ran much better but the plugs were still bright white. I tried the slow idle mixture adjustment but couldn’t get anything to happen when moving the screw……I also read that Twin Cams are tougher than EVO’s to use this method. My past EVO was a no brainer so I know what to listen for but couldn’t hear any change with this bike. I did a number of different rides where I’d back the screw out a quarter turn at a time to now where I’m 3.5 turns out. The bike runs awesome, idles low real good, hasn’t really coughed, and has great power but the friggin plugs are still not brown! They are no longer bright white but they are still a far way from brown or rich black. Any ideas what the heck is causing this? I’m not getting any signs of an intake or exhaust leak, the gasket’s looked good when I took the carb off. It doesn’t lean pop or anything on deceleration. I checked the plug gap and they’re 6R12’s around .040 which should be right on the money. I don’t want to turn the screw out anymore since I read that 3.5 is the limit before it may accidently fall out on its own. Should I try shimming the sportster needle? Thanks

 

Don't worry too much about color on the porcelain of the plug. It takes quite a while to get color, if it's running right. If it runs good and strong, doesn't cough or hesitate, run it for a while. Get in 3rd gear and slowly roll the throttle up and back down. shouldn't have any dead spots or sudden bursts of power.

 

Get a pair of Khromewerks drag pipe baffles or put the old one s back in. Hard to get a Twin cam running well under 3500 revs with no baflles. As long as there is no signs of overheating the plugs, don't worry too much on the color running gas with alcohol vin it.