Piston size??

[blaster_01]

So when i bought my blaster the kid told me it was bored out but he forgot how much it was bored out and i need to buy a new piston and rebuild the top end....iam pretty sure its a wiseco piston but not sure......and what come with the top end rebuild kit from wiseco......and is wiseco the best way to go for a new piston or is there another place to go??

p.s. quad was built to race so the bike is port and polished, bored out, high compression cylinder head plus a ton more

 

[Herpderplol]

You need to take the head off, and measure the bore.

We cannot safely tell you what size there is or what do buy. You need to know where its at.

Do a leak test first.
Do a compression test first.

Whats reason for a new top end??

 

[Blaaster]

If one is going to the expense of buying a new piston then a bore and hone is in order.

The machinist must have the piston in hand if you choose to go with a forged one.

When it comes to the best way to go, there is no best way.

A cast or forged piston will serve as well as each other, both are suitable for racing.

 

[blaster_01]

when i measured the piston it came out to 2.5 inches which ='s 63.5mm.....but wisceo doesnt have a piston that size....did i measure it wrong??? whats the normal piston size and what would be if it was bored out to 240 like he said? (think thats what the kid said when i bought it)

 

[Wifesblaster]

when i measured the piston it came out to 2.5 inches which ='s 63.5mm.....but wisceo doesnt have a piston that size....did i measure it wrong??? whats the normal piston size and what would be if it was bored out to 240 like he said? (think thats what the kid said when i bought it)

What you need to do is either measure the inside of the cylinder with inside mic's or measure the piston with calipers. If you do not feel comfortable doing that then take of you head, cylinder, and piston. Take the piston to a shop and have them order you one. If they charge you to much have them tell you what size to order.

Why are you ordering a piston? Is compression low?

 

[blaster_01]

my piston tore apart and theres a chunk missing now.....so need to tear down and replace piston

 

[Wifesblaster]

You need to split the cases now. Do not try to just put a piston in it and go.

 

[davenichole]

your piston could not have measured 63.5mm stock bore is 66 and max bore on a factory cylinder is 68.25 a big bore cylinder will be at 72 and can go up to 73 or so.

 

[Herpderplol]

Measure with ruler and you can be way off...

 

[Blaaster]

my piston tore apart and theres a chunk missing now.....so need to tear down and replace piston

One may just get away with out splitting the cases.

By the look of the lower ring, nothing may have gone down past it.

All the debris may, and I say may, have been expelled out of the exhaust.

Check for any signs of aluminium particles around the case area.

 

[ajaysblaster]

What level of octange were you running your quad. I say the looks of that piston you need to be running some race fuel or av gas.

 

[gb blaster]

You need more then just a new piston put a pick of them cylinder walls up. I bet they need a bore. Also with the piston Breaking its probably located in ur case right now.

I'd split the cases and clean them if I was u.

 

[Blaaster]

my piston tore apart and theres a chunk missing now.....so need to tear down and replace piston

If that bottom ring is complete and not broken the possibility of debris passing to the crankcase is minimal.

The only other way that debris can get into the case is via the transfer ports, while likely, the chances again are minimal.

There is a very good chance that the piston debris exited through the exhaust.

Usually I would advise a splitting of the cases, but in this situation, if no traces of shrapnel are observed below ring level then it may not be needed to split.

The carnage was possibly caused by poor jetting practices or an air leak, resulting in a lean mixture which caused detonation.

 

[blaster_01]

ya pretty sure i had a leak somewhere.....i started leaking oil a few days before :/
and ya i dont think anything fell down cause I found one chunk of the piston still sitting right on top when i got the quad home and the cylinder is perfect nothing sored or wrong there