So I was riding the other day, 100+ mile trip. When we got to the destination, one of my spark plugs popped out of the engine. I was able to screw it back in and made the 100+ miles back home. Today I went to replace the spark plugs and noticed something really wierd. On the cylinder that had the spark plug issue, I couldnt screw in the new plug. All the others went in fine. I actually stuck the plugs in with the spark plug socket, and the whole thing goes in deeper on the bad one. It almost seems that the hole where the pug screws in got bigger ( wider diameter) or the threads possibly sheared of a little making the hole seem larger. I had to do what I had to do, I put a bunch of thread sealer tape around the thread of the plug and screwed it in the best I could. I fired it up and it seemed totally fine.

Anyone ever heard of something like this?

 

if it took the threads out, thats not good. that plug will blow out again. pull the plugs again and compare the threads with a good one. you may end up needing to put a time sert in that hole to repair the threads. that would be a lot better than getting a new head.

 

but if you need a new head i just bought a new motor for the bottom end so the head just kinda is sitting on my bench

 

I pulled all the old plugs. All the threads are fine on all the plugs and they look exactly the same, even on the one that popped out, so it didn't damage the plugs.

 

The plug threads are steel, the head threads are cast alumnium. Look at the threads in the head for damage.

 

Ugh!!! Taking off that head is a PITA!!!!

 

lmao try a motor swap... i'd much rather do the head again