Removing spark plug boot fixes misfire?

Alright so I get my carbs back from WiredGeorge and the bike fires right up. Idled pretty good so I decide to take it up the street. Ran like hell and Popped when I really got on it wich I assume is gas that is not being burned and hitting the hot exaust. I know the carbs are in good condition because I heard em on his own bike when I picked them up and they were perfect. So I at this point am thinking spark. Get back home and sure enough #1 is cold. I can actualy hold it after about 5 miniutes of idling followed by about 10 miniutes seein how fast she would go. I can not only touch but hold the exaust. I start the bike and pull the plug boot off. I notice as I get the boot slid down about an inch the misfire goes away and it purrs like a kitten. The plug wire is far enough so that I can see the spark well. I plug it back in and the misfire resumes. I am all stock exept the wires are acell 8 mm.

8mm wires? Are they still copper core, or carbon core? The stock wires are copper with a resistor in each plug cap. Carbon core wires don't yeild the proper resistance.

One possible cause of your problem might be that the plug cap isn't making good connection to the wire. The stock plug caps screw onto the wire. You might try pulling the cap off of the plug and screwing onto the wire a little tighter. If that doesn't work, unscrew it and take if off, check to see if the insulator is split. If so (and it's not split too far), you can trim it back beyond the split and screw the plug cap back on. You can only do this so many times before the wires become too short to reach the plugs.

If this doesn't work, you need to pull the cap off of the wire and test the resistance of the cap. I've had one go bad on me before...

Let us know what you find...

Post edited by: guitargeek, at: 2006/07/26 00:00

actualy I dont have plug caps on my wires. Just regular accell wires (automotive) and a spark plug. they are copper. do i really need caps? The bike didnt have any when I got it. so I didnt put any one when I changed the plugs and wires.

Do you have the stock coils?

They are copper wires? I missed that the first time I read your response (need more coffee). If they're copper wires then the cap that goes onto the plug should have a resistor in it.

Yeah, it might be a bad spark plug... Have you pulled out the plug to see what it looks like? Clean and gap it and see what you get.

Post edited by: guitargeek, at: 2006/07/26 14:12

Probably a bad spark plug.

That's actually an old trick for clearing fouled plugs, pull the cap off and hold it about a 1/4" away from the plug.

I had a H1 500 triple that would foul #2 plug pretty consistantly, I'd just lean over and pull the cap and do that while riding down the road, worked every time

You used to be able to buy spark plugs with a gap in the center electrode to use in motors that burned oil and fouled plugs, same principle, don't know if they are still sold though.

the plugs have about 30 miles on em.

IlllMikeIlll wrote:

the plugs have about 30 miles on em.

Hmmm. Okay, but have you pulled your plugs to look at them? Maybe swap them around?

What do the plug caps (boots) look like? Are they the kind where you leave the nipple on the end of the plug, or do you unscrew that?

I still think the problem is where the wire meets the cap (boot). What happens when you wiggle the plug wire without pulling the cap (boot) off of the plug?

i have the caps to the plugs on. they look like the plugs on a car... same wires too. wiggling it does nothing. dosent run right untill you can hear the spark.

I can only guess that the little metal clip inside the plug/cap/boot/whatever isn't making good contact with the sparkplug...

If these are copper wires, shouldn't they have resistor caps on them? Somebody who knows more than I do should step in here... :huh:

that is my logic as well. the problem actualy goes away only with the connector on the wire about an inch away from the plug. good spark and the cyl. starts firing. it is always #1. When I plug the wire into the plug or even get close to it and the combustion stops. Pull the wire away far enough to clear the boot and see alittle of the spark, right at the point where you can just hear the click click click of the spark making the jump. all of a sudden exaust gets hot, runs smoothly, backfires a couple of times, but all is good. This is what I dont understand. How am I getting better fire unplugged than I do plugged in.... I have been workin on this bike for 8 months now. I could be riding a new one for what I have spent. So what should I replace next... lmao.. Replace till repaired. I know both of my coils are good. I got brand new spark plugs. new filters. fairly new engine. New carbs. Im going to burn this bike....

:huh:

(scratches head)

Lou, you out there?

I'd have to guess a bad plug cap. It could be that it allows the spark to short to the engine when the cap is on. When you lift the cap, it is no longer close enough to the engine so the spark has no choice but to go through the spark plug instead.

But it's only a guess.

It wouldn't hurt to swap plugs around to see if the problem follows the plug (as suggested already). I've seen plugs go bad in goofy ways before too.

Post edited by: loudhvx, at: 2006/07/27 01:46