my top end blew :( help my find out why pls

[moosinatrix]

ok so i was out riding around, i was chaasingmy brother through the neighborhood as he left to the store, i was flying pinned out when my bike started making some nasty metal on metal pinking, tinking clanking all that jazz.

i tore down the topend and sow quite a bit of scoring on the cylinder walls and piston as well as some knarly chew marks on the head and top of the piston.

posting pics in a sec.

 

[MotorBicycleRacing]

damage is probably from the rollers in the top end needle bearing.

 

[moosinatrix]

here's some pics

 

[moosinatrix]

and the piston

 

[moosinatrix]

also since im replacing the top end anyway, might as well upgrade. any suggestions to top end kits that boost performance with minimal modification??

 

[moosinatrix]

alsomy piston has a very small bit of play between wrist pin and connecting rod

 

[Bikeguy Joe]

Could have been the ring alignment pin, or as stated above (if you have them) a needle bearing got loose in there.

Or just chinese QC gone awry.

 

[Bikeguy Joe]

Although I will say you have a LOT of carbon/blowby. How old is the engine?

 

[MotorBicycleRacing]

alsomy piston has a very small bit of play between wrist pin and connecting rod

remove the piston from the connecting rod and check the bearing.

 

[moosinatrix]

Although I will say you have a LOT of carbon/blowby. How old is the engine?

engine is 4 yrs old, sat out in wather for a a year or so with no plug in it, guy i traded it to never fixxed the electrical and stole the plug out of it. so... i got about 150 miles out of it.

 

[moosinatrix]

anyone know where i can get a good deal on a complete topend kit for a decent price??

 

[moosinatrix]

Found the culprit bah humbug

 

[Greg58]

You need to know who made the engine, there are different wrist pin locations. I have a grubee and a bgf and the pistons and cylinders are not the same. I would measure the distance from the pin to the top of the piston and post it here, someone might be able to help.

 

[moosinatrix]

its a BGF kit bought from ebay 3-4 yrs ago

 

[Greg58]

You need to check the connecting rod for damage, a bearing that bad had to scar or distort the rod. It may cost less to buy a engine.

 

[moosinatrix]

actually, the connecting rod it 100% unscathed, not even the tiniest scratch.

Wrist pin was pretty beat up though.

 

[Chubbz McNasty]

She's seen better day's I'm sure... Just my opinion but If I were you I'd go all out and buy a whole new motor. Why put brand new parts on top of REALLY old ones? That's what I would do anyway.

 

[Chubbz McNasty]

Oh and uh, good call on the needle bearing Joe.

 

[moosinatrix]

well this kit has virtually no hours on it cept for what i put on it recently. but i am most likely gonna buy a new kit and have lots of spare parts laying around.