Enclosed is a pic of the head off an ST G4500 I bought (claimed to be a "strong running engine" by the seller). The piston looked like this too. My guess is it was caused by wrist pin retainers(there wern't any left in the piston). I've ordered new piston, ring etc. Heads don't seem to be available. Any thoughts?

Worst case, those little Sharp edges could cause detonation?

Enjoy,

Jim

Smooth out the sharp endges with sandpaper and clean thoroughly. Sharp edges will cause detonation.

WS, I received one like that about a year ago, I called the guy on the phone and explained the problem, he sent me money for the necessary parts which came to exactly half the cost of a new one, I bought a new one. My head and piston looked exactly like that and the ports had notches in them. You can't let a 4500 get above 8,000 rpm.

Here's what mine arrived like, if you look carefully at the right picture you can see half of the circlip still in the piston, the half with the tang is gone.

Looks identical to mine! I should have been more precise, there was 1/2 of one circlip left on one side of the piston. I've ordered about $75 worth of parts at this point. The cylinder liner is not scored so hoping it can be used. Your piston has some 'chisel' looking marks by the wrist pin hole-what are those from?

Those chisel marks are from where the piece of the circlip was jammed in the wristpin hole trying to get out.

Enjoy,

Jim

WSMalley, I would let that one go and buy a new one. The Super Tigers are too cheap to spend money on parts.

The head should be fine -- just rub down the edges of the dings. However, in the right-hand photo, near a bolt hole on the right side, it looks like there are a pair of parallel "dents" on the sealing surface of the head that come close to completely traversing the surface -- they might cause a compression leak. Try the head, & if it holds compression, it will be OK to use -- dents & all.

That's Hobbsy's head with the paralell marks. He hasn't used it yet

Enjoy,

Jim

Tower hobbies has the heads in stock for $30.99

Missed the head on Tower's site. Ordered the other stuff already. Guess I'll give it a try with the old head and see how it works. Thanks, Bill