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Discussion Starter · #1 ·
If any of the Guru’s could help me. I am experiencing a bad stutter at low rpm with popping at the exhaust. It happens from idle to about 3000rpm and then clears.
I feel it the most in second and third gear while cruising at 2500-3000rpm.
Almost feels like the timing is off, but this is a 95” TC.

I put some new plugs and the bike ran good for about5-10miles then started to act up. I pulled the plugs when I got home after about 15-20 miles and the front plug was white with some very light coloring and the rear plug was all black. The rear plug was not wet or oily in any way, just dark and dry.

I switched the plugs around and took it around the block. I pulled the plugs and the rear that was the front had now turned brown in that short trip, and the front plug was starting to clean.

Help……….. What could this be?
 

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Try 2 new plugs. Always a good starting point for possible ignition problems. Then try some tests to see if you have a bad rear plug wire.

Happy New Year!
 

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after changing the plugs check for a intake leak
 

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Had same problem once last summer with my 1200 Sportster.
Turned out to be an intake leak.
 

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Discussion Starter · #6 ·
Want to thank everyone for the replys. The gas is freash. I have also tried different plug wires and coil all known to be good.

If anyone has other ideas I would love to hear them.

Thanks
 

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More information would really help. Is the bike EFI or carb'd? Are you using a Power Commander, SERT, or aftermarket ignition? Do you know what the plugs looked like when the bike was running well?

Ragnar
 

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Discussion Starter · #8 ·
Ragnar said:
More information would really help. Is the bike EFI or carb'd? Are you using a Power Commander, SERT, or aftermarket ignition? Do you know what the plugs looked like when the bike was running well?

Ragnar

This is a 95” build with SE performance heads, SE forged pistons (10:5) SE 6200rpm ignition with 10 degree retard, 258 cams and a Rivera 42mm side draft kit.

The plugs before looked good, just a little on the rich side. Just strange how there is such a huge difference between the two plugs.
 

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Eh Bruddah,

Did you check for the intake leak? Just take a can of carb cleaner or WD40 and spray it around the intake, and throttle body. Do it at idle and at the rpms where it happens. If you hear the engine speed change, you found it. Sometimes a little one can sneak by you. Also check and tighten down the exhaust too.

Good luck Brah,
Laters.
 

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Is the bike fuel injected? Slight chance it's a leaky fuel line in your tank. I would check the above things first.
 

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Okay, let's think about this. You're running a high compression big bore with SE ignition. The plugs, wires, and coil all seem to be fine. The intake leak is an easy test, and I'd try that just the way it's been suggested. I'm doubtful that this is the cause though, since the problem seems to cure itself in the upper part of the mid-rpm range. But still, the leak test is easy, so you may as well do it.

The next place I'd look would be the ignition. Can you disconnect the SE ignition and run the bike (not hard; just run it) without it? If it performs passably, you've found the problem. If not, you've just eliminated one more thing.

Good luck,
Ragnar
 
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