old piston...

[sickOne]

this is the piston i just got out off my bike, pretty bad, any sugestions on why this happen, this is my first rebuild on a 2 stoke but i know this is not normal, i was riding pretty hard that day but not to kill a piston like that, got lucky that there was no damage to the cylinder

 

[doc_speeder]

Might want to check your cylinder pretty closely. That's a lot of damage on a piston to have no cylinder damage.

Still running the oil injection pump? Looks like it got run dry (gas only)

 

[sickOne]

yea i know i did...we did some clean up but thats about it, it just kinda melted to the cylinder didnt scrape it, some huning and looks great...i premix

 

[kx80berger]

you may have ran it to lean

 

[nofxfan125]

Might want to check your cylinder pretty closely. That's a lot of damage on a piston to have no cylinder damage.

Still running the oil injection pump? Looks like it got run dry (gas only)

I don't think running no oil would cause that. That would cause the crank to cease if anything. I'd bet the cylinder got real hot and melted the piston like that. a.k.a. lean jetting OR if you were running Wide Open Throttle and then just let off the throttle completely. That would cause the air/fuel mix to go lean and the engine would over heat.

 

[nofxfan125]

I wonder why there is no carbon built up on top of that piston...

 

[Blasterdude27]

lean jetting OR if you were running Wide Open Throttle and then just let off the throttle completely.

My thoughts exactly.

 

[Paulie B]

Thats one of the most worn pistons I've seen that didn't shatter.
You got real lucky!
I'm guessing your a tad lean on your main.

 

[Tim Lutz]

I wonder why there is no carbon built up on top of that piston...

Because the carbon melted off just before the piston started to. Classic lean condition. It will always melt away the first ring land on the exhaust side. Your luckey the skirt didn't break and hose your bottom end.

 

[stephen12091985]

yea i agree with everyone else lean jetting

 

[sickOne]

I wonder why there is no carbon built up on top of that piston...

there was some carbon build up i cleaned it off to look at the serial number for the piston....i was thinking the same its running lean but the problem is that i bought the quad as it is right now so i dont know much about what was done to it or what kind of jets it has i know is has a over 90 bore cuz i read the numbers on the piston and got the matching one its a wiseco pro lite, it also has toomey b1 pipes and notice it has a hot rod conecting rod, it has stock reeds , im gonna put i back together today but i dont wanna have the same problem again, i ran the bike for like two months it was running good until that day that this happend...now what should i look for?

 

[yb200]

it should have atleast a 310 main jet

 

[Tim Lutz]

I'm going to say if your main jet was not clogged or smaller than a 270 then that was not your problem. Check your floats they may be set really low. Check for air leaks, Cracked carb boot, bad reed or base gaskets. Could also be a bad left crank seal. What's the plug look like?

 

[doc_speeder]

Too bad it's .90 over, as I think that is max bore.

 

[sickOne]

it should have atleast a 310 main jet

would it say the size of it when i take it out...cuz im gonna put the head back together today but im not gonna fire it up yet,the bike been sitting for a while so im gonna open the carb to clean it any way, and do an oil change too, i guess im gonna have to go thru everything to make sure i dont have any air leaks....its gonna be my first time opening this carb so ill be posting what i can find, i might need some help with it

 

[little3mil]

do a leak down test... I did the same thing to my motor and couldnt figure it out untill my friend leak tested my motor and I found 2 HUGE air leaks (which in time leaned it out bad) If you have leaks a rebuild is just a waste of time, untill you find it and fix it. FYI my leaks were at the reed cage gaskets... black rvt wored GREAT!! my 2 cents
good luck

 

[sickOne]

it should have atleast a 310 main jet

i think it says 300 on it is that to small...but i think my intake may be leaking cus i notice one of my screws was missing

 

[Tim Lutz]

i think my intake may be leaking cus i notice one of my screws was missing

Bingo. You found the problem.

 

[sickOne]

i also didnt find any gasket it had some black rvt....is it supose to have one gasket between the boot and one between the cage? cus my kit only came with one

 

[yb200]

i also didnt find any gasket it had some black rvt....is it supose to have one gasket between the boot and one between the cage? cus my kit only came with one

use the gasket between the cylinder and reed cage and rtv between the reeds cage and manifold