Piston Failure

[AlisoBob]

http://cr500riders.com/cgi/yabb/YaBB.pl ... ;start=all


Let me get this straight... The machinist screwed the pooch on this one, so the owner gets to buy a new piston " at cost" ,buy new gaskets, and donate his labor for free, and the machine shop gets to skate off into the sun set?

That crap wouldnt fly around here...

[britincali]

From looking at the pics I dont think he put the ring gap over the locator pins.

[britincali]

Those rings look to be stuck, if so they haven't moved since it was assembled.



Look at where the top ring gap is.............

[AlisoBob]

The bottom ring is stuck, and in the correct location.

The top ring is loose, and has moved.

Th jug isnt going on if the rings are over the pins.. no way.

They should send that piston to the Janitor for a solder job..

Good as new!

[britincali]

Th jug isnt going on if the rings are over the pins.. no way.

[ou812]

The exhaust port edges are knife edge sharp

[AlisoBob]

It you were to rotate the top ring by the amount it needs to more to line up with the pin, there is a shitted up part that would then line up with the rest of the black death...

The rings were located correctly.

[britincali]

It you were to rotate the top ring by the amount it needs to more to line up with the pin, there is a shitted up part that would then line up with the rest of the black death...

The rings were located correctly.

If thats the case then that piston must have been as tight as a nuns c**t.

[Ported&Polished]

Well, it's just one more example of why a Wiseco piston is not worth using. To many oddball issues to deal with, like drilling holes, releiving bridges, critical tolerances, seasoning of the piston, blah blah blah blah blah. Just run a fricken ProX and go tear it up.

[100hp honda]

something doesnt look right in that picture. top of the piston has no discoloring or carbon to it, and theres none anywhere else. ill bet that thing leaned out like a mother fugger. and maybe some crappy machine work. worst damage was around the bridge area . apon further thought, if the bridge wasnt relieved and the piston came up to temp, your going to have serious clearance issues. causing the bridge to melt to the piston and push it against the highest points in the cylinder (the marks where the studs are). it didnt live long, whatever the case was

[100hp honda]

Well, it's just one more example of why a Wiseco piston is not worth using. To many oddball issues to deal with, like drilling holes, releiving bridges, critical tolerances, seasoning of the piston, blah blah blah blah blah. Just run a fricken ProX and go tear it up.

theres a big misconception about wisecos and people fear what they dont understand. there is no "seasoning", and no 3 day special breakin routine. fire up the bike, let cylinder get warm, start riding casual, whack it WOT through the gears for 15min. all your doing is getting a new piston accompanied to a new cylinder envirnment. only thing i recomend is not holding it WOT for more than a second or two for the first few minutes. aint no big focken mystery to this shit. and make sure ALL clearances are correct but that applies with any fuggin type of piston

[AlisoBob]

Well, it's just one more example of why a Wiseco piston is not worth using. To many oddball issues to deal with, like drilling holes, releiving bridges, critical tolerances, seasoning of the piston, blah blah blah blah blah. Just run a fricken ProX and go tear it up.

yup.....

[100hp honda]

Well, it's just one more example of why a Wiseco piston is not worth using. To many oddball issues to deal with, like drilling holes, releiving bridges, critical tolerances, seasoning of the piston, blah blah blah blah blah. Just run a fricken ProX and go tear it up.

yup.....

put me on the list of cracked cast piston owners

[britincali]

At least forged pistons dont shatter and take out the bottom end when they go.

[Ported&Polished]

Well, it's just one more example of why a Wiseco piston is not worth using. To many oddball issues to deal with, like drilling holes, releiving bridges, critical tolerances, seasoning of the piston, blah blah blah blah blah. Just run a fricken ProX and go tear it up.

yup.....

put me on the list of cracked cast piston owners

Wow, a ten year old stock piston with a crack, who'd of thunk it possible. You could run the cracked piston for another couple years prolly. As for the forged piston not needing seasoning, I beg to differ. They expand and contract for several rides before they fit the cylinder right, that's why they have seizier issues and need holes drilled. They are really meant for racers that rebuild the top end every 3 races, not for everyday riders that want the top end to last for a couple years.

[AlisoBob]

At least forged pistons dont shatter and take out the bottom end when they go.

This only happens when you:

1. Exchange one cracked piston for another new one of the same size without correcting the piston to wall clearance issues.

2. You leave that piston in until it cracks cuz your a cheap ass from Manchester.

Cast is the correct choice in 90% of the applications.

[dannygraves]

I've had a Wiseco in mine for over 1 1/2 years with A LOT of riding and abuse on it. No sign of any need for a new one any time soon. Shitty machine work and poor tuning are the cause of %100 of wiseco piston failures. I ride the piss and snot out of my bike, and have even overheated it really bad a few times.
That guys machine shop didn't leave enough room, they probably did some half-assed measuring, and he was probably also running too lean. Got that piston too hot. Plus I don't see a nice coating of oil on that piston. Assembly could have been done a little too dry, I cover everything in 2 stroke oil before assembly. My last topend which was on the bike when I got it didn't have holes or the bridge releived and had some tiny bit of gouging and still ran, the bridge isn't the main problem but just part of it.