yamaha blaster piston failure
- Thread starter cpcoop71
- Start date
If you can, do a leak down test BEFORE you tear it down. Will help determine why it blew. Did it stop with a clunk?
If possible do a leak down test to help diagnose why it blew up.
Edit. Quick draw Mc Graw strikes again.
Edit. Quick draw Mc Graw strikes again.
not sure If I have time for the test because its a friends and he isnt happy though the top end was going anyway. will post pics. Yea it stopped like it was out of gas. a little bit of smoke like it got hot. I could move the kick starter but wasn't as easy as normal.
Sounds like a slow seize, which could have been caused by an air leak leaning out the fuel/air mix.
Maybe caused by a lean mixture overheating the piston crown!
The kickstart would be hard to push down, because the piston may have deposited some aluminium on the bore, and the rings are grabbing it.
someone kicked it over after it died and it ran. just sounded bad so he shut it off right away. got the parts on order. when i can pull cylinder off I will take pictures of cyl and piston. I'm thinking it got too hot. I was riding it pretty hard through mud and not going very fast. I am starting to dislike air cooled bikes.
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I too am thinking that it got too hot, possibly caused by detonation caused by an air leak or poor jetting.
If you can, do a leak down test before you pull it down, you now may have a hole in the crankcase, especially if the piston has dropped a skirt.
Please post your mods and jetting numbers, so we can see why it may have overheated.
an air leak is what will cause the piston to get too hot and expand beyond the bore size. you MUST musT musT do a leakdown test on a two stroke after any work on the intake head or base gaskets!! order one from slickerthanyou on the forum. they are cheap and ez to use
EDIT. while you are at it order an oem headgasket and base gasket. Also a couple intake gaskets.
same thing just happened to me 3 days ago, except i believe its the piston "skirt" that broke off and fell down into my case. i take my motor apart and took pics. i'll be starting my own threaad about it so i dont hi-jack this one lol. good luck with your top end etc...
^ im in the same bout as you guys, had my liquid cooled blaster out in the pits running it hard. i think running too small of a rad and alittle to many Rpms keepin up with the banshee caused it to heat up abit. it suddenly completely lagged out power and started working real sh*tty. i towed it home haven't got to it yet but i may be having a similar threat.
Weisco will have part # and size such as 66.75, others such as stock will have P1, P2, etc , tho not necessarly on top, might be on inside.
opened it up. couldn't snap a picture yet but piston was a bit chewed up on the top and a little on the sides. Was like it went too long before a piston change. put new piston with arrow facing front, rings with wording facing up lubed everything as I put it together with all new gaskets wrist pin, needle bearing, circlips. tried to start it and got a backfire.
gonna pull it apart. will check reeds, recheck that rings are set correctly. not a whole lot of up and down rod play. Anyone know where I can find the tool for a leakdown test?
gonna pull it apart. will check reeds, recheck that rings are set correctly. not a whole lot of up and down rod play. Anyone know where I can find the tool for a leakdown test?
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