Hi folks - 1st time Harley owner here with a problem.

I recently bought a '96 Heritage Softail Classic w/7600 miles on it. I figured that the bike was practically brand new (due to the milage) and I would have no problems with it.

The trouble I'm having is that my plugs are fouling out about every 300-400 miles. I've talked to alot of people I know & work with about it & they all tell me that it has to do with carboration. I get opinions that range from re-tune & rejet my carb all the way to replace my exhaust (the bike is completely stock). A bit more information: it seems that the rear plug fouls about twice as fast as the front.

I'm told that due to EPA requirements, Harleys come off the line this way and after @ 1000 miles, the carb should be retuned/rejetted & its possible that this was never done to mine. Others have told me that my engine is starved for air & I need to put a new exhaust on the bike (which seems silly to me - why would Harley sell a bike with an exhaust system that constantly fouls plugs?).

Any help would be appreciated. I'm mechanically inclined (read: I fix my own vehicles), but this is my 1st go around with a motorcycle & I really don't want to mess my ride up - nor do I want to drop $1000 on an exhaust system after paying $11k for the bike! Thx in advance.

 

Sounds like too rich a fuel mixture. Do you use the enrichener/choke often or has it perhaps been left out and you not know it? Sounds like you might need to rejet.

 

After changing out my 1st set of plugs (I always used the choke to start the bike & left it on for a minute) - I was told to always start the bike without the choke if at all possible & just throttle warm it. Since then, I've only used the choke a time or two and have instantly pushed it in as soon as the bike started & continued with the trottle warming.

Everyone has told me its running too rich, the problem is - why?

Thanks for the fast response.

Update: Just spoke w/ a local bike "guru" - he suggests starting with a Dynojet kit (although he also mentioned a new exhaust system). At least I found someone who's willing to let me hang around & get some wrench time. The local HArley dealers just keep telling me to bring it in & let them do a diagnostic test on it. I don't have issues with a dealer doing work on my bike, but GOOD GOD, at least talk to me about the problems & possible solutions - I don't wanna be dealer dependant forever!

 

You can get a good set of mufflers, a high per air cleaner, rejet and a dynotune and you should be good to go. There are lots of choices out there for mufflers. I went with Vance and Hines. Good luck and keep us posted.

 

I agree with dawg on the choke and air flow deal. I plagerized the following from badmo on another thread that sums up pretty good what causes fouling.

Many factors can contribute to spark plug fouling. The air/fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.

 

Before buying anything, check/adjust the idle mixture screw. I believe this site has "how to" info on that. Get that adjusted correctly first before preceding to anything else. Turn the screw all the way in until "Gently" seated keeping track of how many turns (sample : like 2 1/4 turns), then turn it back out 1/4 turn less then what it was and road test. You don't want bigger jets right now if running too rich. Also what plugs are you using? Champions will foul real easy, any plats will resist fouling much better then factory plugs.

 

Thanks for the help - hopefully, this weekend, I'll be back on the road. Turns out, after some checking today, I DO NOT have a stock exhaust. It looks like the guy that owned it put fishtail slip-on mufflers onto it. Hmmm.

I put whatever the dealer gives me when I say "Gimme some plugs for a '96 Heritage Softail Classic" - they say "Harley-Davidson" on the side (I do, however, check to make sure the gap is set to .040").

I will be checking out my air filter today to see if its loaded with oil (haven't done that yet).

I'm thinking the guy who owned it didn't realize that new mufflers & rejetting go hand-in-hand. I'll let you folks know how things turn out.

I'll also be checking the idle mixture screw & trying the tip mentioned above (thx ReeseSS).

 

Try a 190main/45 slow jet. Turn air/fuel out 2 1/2 turns.

 

I'm having a very similar problem with my 2001 xl1200 sportster. I have free flow pipes on it and have tried a couple different slow jets. Ive put a 45 and the 42 is what is in there now. Still runs too rich. What was your issue?

 

Start a new thread, this one won`t get much attention, it has been 14 years since anyone posted in it...