[GPz Aussie]

Friend has brought his 92 gpx250 to me to fix (I do IT by day, just hobby mechanic learning as I go by night) he told me he accidently put too long spark plugs in and when he tried to start the piston hit the plug. I've popped the head off and can see a small dent on the piston from impact, what should I expect to replace. I'm presuming the piston, but it's gudeon pin seem solid should stuff like that go too? Should both sides be done (one piston dented one was scratched. I've rebuilt air cooled 750s and gpz600r's but nothing with serious physical damage yet so sorry in advance if I sound noobish.

 

[earlthepearl]

That's a hard one to really say.
Myself......
I tear it down n check just a bit deaper, but.....
I knew a guy that did that same thing n he just changed plugs and ran it, but....
It wasn't a high rpm engine either.....
Maybe pictures would show as more....

 

[Blue Ghost]

It all depends on the amount of damage and how much the owner wants to invest to keep a 22 y/o (and no telling how many miles) bike running. Pistons are pretty rugged. A dent and a scratch can be insignificant. I'd inspect them really good, adjust the valves, install the correct plugs and ride see if it runs. Ride till you can't ride it it anymore.

 

[earlthepearl]

It all depends on the amount of damage and how much the owner wants to invest to keep a 22 y/o ( and no telling how many miles) bike running. Pistons are pretty rugged. A dent and a scratch can be insignificant. I'd inspect them really good, adjust the valves, install the correct plugs and ride see if it runs. Ride till you can't ride it it anymore.

:thumb:....I just didn't wanna be the one to tell em that...LOL....
But yeppa....just what i'd do on a ol bike myelf.....
Just dont run the total piss outta it...

 

[byte2022]

It all depends on the amount of damage and how much the owner wants to invest to keep a 22 y/o (and no telling how many miles) bike running. Pistons are pretty rugged. A dent and a scratch can be insignificant. I'd inspect them really good, adjust the valves, install the correct plugs and ride see if it runs. Ride till you can't ride it it anymore.

100% agreed. May be insignificant dent and scratch but definitely inspect it good. Do what ghost mentioned above and ride it like ya stole it. But only after you ride it easy after all is done. Listen to the motor real good. If something don't sound right stop and re inspect the piston again and go from there