Hey guys,

I'm wondering if anyone can give me a solid answer on an issue I just ran into yesterday before I take it in for service.

Model: Sportster '05 - XL883

Short story: I did a simple oil/filter change yesterday (done it 3 times before) but this time I decided to also change the spark plugs. First start everything was fine then after a few miles I noticed I couldn't rev high otherwise the bike would feel jumpy and the exhaust would pop loud. I also noticed that the bike would feel as if it had low power when the choke was completely in. I put back the old spark plugs and the bike runs great like before but I still get black smoke when I rev it high. Why can't I use the new spark plugs and am I due for a service check?

Hope someone can give me a straight answer on this one.

Cheers,
Steve

 

How is the oil level, you did not overfill it did you?
Oil can get sucked into the intake and burned if you over fill it.

plug type, gap?

Air filter clean?

Brett

 

Hey Brett,

Really appreciate the reply. I did overfill the fill line on cold but when the oil is warm it's in between the low line and full line. I checked the air intake earlier and seemed pretty clean other them some dirt at the bottom edges on the outside. I didn't make any adjustments to the new spark plugs (6R12), the gap is left as is from out of the box. Old spark plugs are back in and bike runs fine other then some black smoke on a high rev. Should I just leave it to HD to make adjustments? Should I be concerned? I would love to get rid of the gas small and black smoke.

Steve

 

Is the black smoke at high revs coming when you're reving it up, or immediately after you let off the throttle? If it's when you let off the throttle, you have bad valve seals. This is a known problem on all 05 Sporties, they were a defective design from the faactory.

New plugs need to be gaped, .038"-.043"

 

Charles,

When I rev it up high black smoke comes out, I didn't notice anything when I let go. When you say .038"-.043", do you mean the gap needs to be in between these 2 numbers or the first cylinder is .038?

THX
Steve

 

Bump!

 

What brand are the new plugs??? If your just reving it up out of gear you will get some black smoke from the accel pump adding too much fuel because the engine is not under a load.

If its doing it at highway speeds +70mph then it might be over jetted on the main.

Also if reving out of gear you will hit the rev limiter.. I think i read its 52-5800 rpm on a stock module.

 

You sure you didn't crack an insulator on the new plugs? I did that in a car once and didn't question it. ran fine down low, but put it under load or high RPM's and she'd pop and smoke. Could also just be a bad plug from the start. As for the smoke, is it getting any better as you run it? Usually a sign of too much fuel and carbon in the cylinders of just a good ol' rich set-up.

 

Yes, the spark plug gap needs to be between there. Check the ones you pulled out, just out of curiosity. Good luck! RD

 

Black smoke= unburnt fuel. 1st make sure you got the correct replacement plugs. 2nd make sure the gap is correct. Too tight (gap) not enough spark for proper ignition. Too wide weakens the spark.