piston is busted, i cant find the piston anywhere HELP!

0_o

0_o

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Jan 11, 2011
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it has 8002 stamped and under it it says 72.45mm

look at how the rings and sandwitched and a piece missing.


what should i do next? take it to get machined and go the next cylinder size?
:-/

Is is this one?

http://compare.ebay.com/like/310294...fce8b99&itemid=310294314292&ff4=263602_309572

http://www.blasterforum.com/361764-post10.html
piston051.jpg

piston045.jpg

piston049.jpg


thats what 30psi of compression looks like!
 
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Yeah man.... Bad news with that cylinder. And if you can rotate it in your hand and take a pic of the other side. If it has a cut out on the other side that kind of looks like the helmet to a suit of armor it's a Vito's. lol
 
0_o said:
it has 8002 stamped and under it it says 72.45mm

look at how the rings and sandwitched and a piece missing.


what should i do next? take it to get machined and go the next cylinder size?
:-/

Is is this one?

YAMAHA BLASTER VITO'S 72.50MM 240 BIG BORE PISTON .020 on eBay!

Yamaha Blaster Forum - View Single Post - compression
piston051.jpg

piston045.jpg

piston049.jpg


thats what 30psi of compression looks like!
Click to expand...

Yep, that's what I thought....hole in piston or broken ring.

How bad are the walls in the cylinder.....IE did the ring gouge any part of the cylinder wall badly when it failed? Are there pieces missing? If so they might be in the crankcase and that will need to be addressed. If not, bore to the next size and purchase a Wiseco piston to me that increase in size. After that, just reassemble with a new top end gasket set, tighten everything down to torque specs, do a leakdown test, and be on your way with break in and all is well. I:I
 
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Wiseco doesn't make them in that size anymore. They stopped making the big bore pistons.

Look up the wossner piston in the 73mm. They're the only forged choice left.
 
99LRDblaster said:
Yep, that's what I thought....hole in piston or broken ring.

How bad are the walls in the cylinder.....IE did the ring gouge any part of the cylinder wall badly when it failed? Are there pieces missing? If so they might be in the crankcase and that will need to be addressed. If not, bore to the next size and purchase a Wiseco piston to me that increase in size. After that, just reassemble with a new top end gasket set, tighten everything down to torque specs, do a leakdown test, and be on your way with break in and all is well. I:I
Click to expand...

do i just go in a machine shop and ask. "uh.... can you bore it to the next cylinder size? the inside of the cylinder looks really nice and chrome ill get some pics tomorrow i left it at my friends garage
 
And sort of.... You would definitely want to either measure the cylinder yourself and determine the cylinder size or take it to a local machine shop and get them to measure the bore, taper, and out of round. Compare those numbers to the factory specs and see if the cylinder needs boring.

If it does, you can purchase the piston of your choice (either the cast vito's or the forged wossner) and take the piston and cylinder back to the machine shop. They'll bore the cylinder to match the piston so they'll fit perfectly.

You could also contact an engine builder on this site and see about boring your cylinder out. There are several good choices and they'll all do a good job.

Either way, you'll need to determine what you have right now and then go from there.
 
Namura makes "standard" blaster pistons (66mm through 68.25mm) but his is a Big Bore cylinder. 72mm, 72.25mm, 72.50mm, and 73mm are the available bore sizes. Since you are already on the 72.50mm you may have to step up to the 73mm piston.
 
That looks like a cast piston maybe and oversized Yamaha or WSM

There is nothing wrong with cast pistons. the original OEM pistons from Yamaha have been known to last 3-4 years of hard use. Ive run them in race engines as well as rec machines. Providing you check the compression when you should and Mic everything once it is apart you will never have a problem..
One issue is most builders dont take the time to bore/hone the cylinders to the proper specs and they are loose and dont last.
 
i need some help for my lil bro he's got a 87 trx 250x and the wheel bearings are bad in the front does one side take 2 bearings and seals or does it jus take one i'm not sure? HELP? so he'll quit buggin me bout it i told him should've got a blaster but he dnt listen at ALL. lol. so any help?
 
bigrig said:
i need some help for my lil bro he's got a 87 trx 250x and the wheel bearings are bad in the front does one side take 2 bearings and seals or does it jus take one i'm not sure? HELP? so he'll quit buggin me bout it i told him should've got a blaster but he dnt listen at ALL. lol. so any help?
Click to expand...

they each had 2 bearings a two seals and 1 bushing in each wheel.

A larger inner seal and bearing
A smaller outter bearing and seal and bushing

I think they had a couple different hubs for 86-88 and depending on what bike you had regardless of the year it could have different hubs. BUT all the bearings and seals were the same, only the rotor/drums or hub shape was different
 
The problem with cast pistons is not if they blow but when they blow. You'll have to agree that most people don't do what you recommend and check the engine at regular intervals

Most people run an engine until it stops.

When an engine with a forged piston in it comes to a screeching halt the piston has scraped the cylinder wall and locked the engine up tighter than a drum but GENERALLY it's still in one piece and once it's removed, the cylinder can be bored and re run.

When an engine with a cast piston in in comes apart the piston has a tendency to crumble into little pieces of aluminum which float all over inside the engine and ruin pretty much every bearing and sometimes get between the crank and the case and break it out.

It's not how a cast piston runs that's the concern to me, it's how they blow. I would recommend only a forged piston for replacement in a blaster engine.
 
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Oh I agree... I just get annoyed when people say stupid comments like oh that piston sucks or whatever....
Its a piston. They perform the samem infact some cast perform better because they can be run with tighter cleanaces etc. How it is fitted makes all the difference.
If we could just teach people to inspect the compression and test jetting a lil more often we could save a lot of people a lot of money and put an end to the myths.
 
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