bent spark plug electrode

mikefxst

I have a friend that has an "07 roadking the other night while riding the vehicle suddenly sounded like it was running on 1 cylinder he pulled the front plug and found that the electrode had been crushed all the way closed. Any ideas on why this happened. the bike has 5,000 miles on it and he just switched pipes and air filter to stage 1 kit. he did not have it re-mapped after that. we thought it night be from a piece of carbon but i thoguht with the dtergents in gas and oil its really hard to get that big of a pice fo carbon built up in the motor that would cause the poston to be able to slap the carbon up into the plug. I also wasnt sure if piston travel can incrase suddenly like that but yet after chaging the plug with a new spark plug it has been running fine and we have traveled in the past 2 days around 100 miles. any ideas would be great

Hobbit

i would say keep an eye on it, check the plug on every ride to see if it does it again, i have only heard of one other bike doing this - my dads 1960's BSA gold flash

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glider

Must have been carbon, piston height can't grow that much to hit the electrode.

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Rod Stewart

Detonation?

Something sure sounds strange; plug electrodes don't just bend closed for no reason. I think I would install a new plug just for good measure.

Rod

7 Blairs

Gotta be something in the cylinder....

silentflyer

Might want to pull the oil filter, do an oil change, and cut open the old filter and see if it has any build up of "chunks" and bits of metal in it. Always part of my oil change routine, found busted ring lands in an air cooled aircraft engine once, after finding trash in the filter. At 5k its due a change anyway.

Rod Stewart

If you take it to an engine shop they could boroscope the cylinder, just to make sure there isn't a piece of something flying around in there. Its a long shot, but something sure does not sound right.

Rod

flh canuck

I would also be concerned as it would take something pretty solid to bend the electrode.

A modern Harley engine with only 5000 miles shouldn't have that much carbon if any, built up to begin with.

Sounds more like something foreign might have gone through the combustion chamber.

If he recently changed air filter etc, there is always the chance that something small ended up where it didn't belong (like down the intake, dohhhh!).

I would be inclined to pull the plug and have a real good look inside that cylinder for any additional damage.

As mentioned in a previous post, a boroscope would be ideal for looking around inside there and much simpler that pulling the head off.

You might get lucky and not find any additional damage, but I would want to check it out further to determine what went through there and make sure everthing else is ok.

miabagger

Yep,
Sounds like he sucked something in there, usually one of teh screws that hold the air cleaner on!! Unfortunately the top of the piston is softer that the electrode, so he probably damaged something in there. He should be able to tak e pen-light and check out the top of the piston easily. then just move the piston down about a 1/2" and check out the surrounding area.

dangerdan

I am anxoius to see the outcome on this post

I would be tempted to use a magnetic probe and see if anything metalic comes up with the probe.

Its not a sure thing as carbon, aluminum or ceramic are not attracted by magnetism.