Tri-zinger seized within a week

[russ98atc]

As some of you know i blew up my trizinger with a china pw50 topend around a month ago. Well my christmas present was a new 60cc top end rebuild. I had the cylinder bored .25 over , everything was done right it was honed ,chamfered ,the whole nine yards. I put all OEM in it piston,piston rings, piston pin, piston bearing and piston clips. The only thing was i had the 60cc head shaved and it was shaved to much, so i used the china pw50 head. Also i ordered veshrah gaskets which were very thin(even the china pw 50 head was hitting the piston). So what i did was i made a new base gasket out of gasket paper and it seemed to not hit the head. The next day i broke it in, i started it and let it idle for 10 minutes let it cool down fully, started it ran it around half throttle let it cool, then drove it lightly for the hour after that. The only thing i noticed was that topend when it started to wind it would have a dinging/ringing noise from the top end. then today when i was riding it i was going arond 3/4 throttle then it went bwwuuuuuuuuuuuh and shut off, i went to pull the pull rope and it wouldn't budge. The only thing i can think of is that the piston was hitting the head when going full throttle. I havent dissassembled the top end yet but i will let you guys know what it looks like when i do.



It just sucks rebuilding something and no more than a week later it seizes. Any input would be greatly appreciated.

Russ

[El Camexican]

Ouch! Let this be a lesson to all the kids out there that want to open their presents BEFORE Christmas.;)

Clearance tolerances are highly underrated, invest in some Play Dough, or solder wire and a couple of extra base gaskets when you do the rebuild.

[russ98atc]

So you think that it could of been the piston slapping the head?

[TimSr]

The Chinese 50cc head that I used had a smaller diameter cutout than the stock 60cc Zinger head. If you needed a thicker gasker to clear the head, it was probably hitting the outer rim of the head. Zinger OEM 60cc heads are cheap and easy to find.

Vesrah head gaskets suck. The stock gasket is aluminum, and 2 stroke head gaskets should never be cut out of gasket paper. Probably did not cause your problem, but something to keep in mind.

[russ98atc]

I made a base gasket out of gasket paper not the head. Thanks for letting me know about the head diameter

[Scootertrash]

Was the base gasket you made the same thickness as the original?

[bkm]

I would have like to have known what the compression reading was for that engine before it blew. The sound you heard was probably detonation from to much compression and low octane fuel. The dome was probably way off creating a small combustion chamber and the cast piston didn't like it very much. When mixmatch parts are used they need to be machined to match. Just because something physically bolts on doesn't mean its going to work together and without knowing prior clearances we're all pretty much throwing theories out there.

I did the bore get trashed? If its salvageable I would do a light hone, get a new true 60cc head, and buy the right gaskets and go from there.

[Dirtweed]

Go with what bkm said and also have my brother work on it this time with you.

[russ98atc]

I would have like to have known what the compression reading was for that engine before it blew. The sound you heard was probably detonation from to much compression and low octane fuel. The dome was probably way off creating a small combustion chamber and the cast piston didn't like it very much. When mixmatch parts are used they need to be machined to match. Just because something physically bolts on doesn't mean its going to work together and without knowing prior clearances we're all pretty much throwing theories out there.

I did the bore get trashed? If its salvageable I would do a light hone, get a new true 60cc head, and buy the right gaskets and go from there.


It was getting around 90 psi of compression. I took apart the top end and yes, it was hitting the head. What had happened was the top of the piston on the intake port side was hitting the top of the head, there for angling the piston upwards and dragging the bottom skirt over the exhaust port.

[bkm]

Like I said I was grabbing at straws with my theory, but the piston hitting the head will trash an engine every time.