I am looking for some thoughts on what could cause the ground or side electrode on the spark plug to bend and touch the center electrode.
I have a friend who has a Buddy 125 with about ~18k on it after he changed the spark plug the ground or side electrode was bent into the center electrode twice(basically making the plug have zero gap.) The first time took a few weeks and a few hundred miles but the second time it only took about 10 miles, all at speeds under 45 mph. When running it sounds good and we ran it for 10 minutes on the center stand, even revving it up several times and it was fine. I am thinking there is a chance that it only happens during engine braking which we didn't recreate on the center stand. There was a tiny amount of play in the crank about a thousand miles ago when I changed the belt, but it was tiny and I could only feel it once in a while, and I don't know how much play is acceptable in a crank. Also, there is a chance the spark plug was loose after being bent, but if it wasn't all the way tight that should have kept it further away from the piston.
It would seem the only good answer is the pistons is touching the plug and bending the side electrode, ideally this isn't the problem because it won't be an easy fix. So I am wondering if anyone has any other ideas what might be causing this or any easy fixes? If it is the piston hitting the spark plug would running a colder spark plug help since the plug wouldn't stick as far into the cylinder? (EDIT: after a little bit of research I don't think a colder plug will fix the problem since it should be the same length but made a little differently.)
If you have any ideas or need any more information let me know.
Spark Plug issue on a Buddy 125
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scootERIK
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nobade
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Re: Spark Plug issue on a Buddy 125
Are you sure it is the right plug?
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scootERIK
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nobade
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Re: Spark Plug issue on a Buddy 125
125 isn't supposed to have a resistor plug like the 170 but it should be the right size. No way the con rod bearing is loose is it?
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scootERIK
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Re: Spark Plug issue on a Buddy 125
The new Buddy 125 owner's manual has the spark plug listed as a NGK CR7HSA. My understanding is the 125 doesn't need the resistor but it works fine with it and it is getting hard to find the non-resistor plugs since a lot of stuff needs the resistor(but I could be wrong.)
The crank bearing might be starting to go, there was a little bit of play up and down on the CVT side but I couldn't always get it to move.
As for the con rod bearing, I'm not sure if it could be loose. When it is running the engine sounds really good. My mechanic thought I had a con rod bearing go on one of my Buddy 125 engines and when it went there was a lot of rattling. But it could be part of the problem.