500 miles and boom

Desert Rat

Desert Rat

New Member
Just a note, was out riding and I heard something go chink so I stopped the motor
got home pulled it apart and gouges just below ports and the piston was pretty
gouged up would spin freely with no compression but the rings were intact.
The culprit: the retaining spring holding in the wrist pin!
go figure. LOL
ad pics later
 
Sorry to hear that DR,
Parts are cheap though.
And if damage to barrel is below compression area, might just need a piston set?
 
One of the reasons I de-jug and inspect all my new kits. I've found a few with incorrectly seated circlips. Also check ring end gap is correctly aligned over pin. I've found several jammed rings that would have destroyed the engine upon starting.
The chinese factories have spotty QC at best...it's just prudent to check it before running.
Could also have just been a fluke failure, but I'd guess it wasn't fully seated and worked it's way out.
 
I wish they'd sell these things unassembled. I buy my bikes dirt-cheap delivered from Walmart and they hold up well, the reason so many people complain about the quality of Walmart's bikes is less the material quality and more the assembly skill and care taken by the minimum-wage teenagers who build the bikes when they're delivered to the store. I ALWAYS completely disassemble my engines and rebuild/replace parts to my liking.
 
What assembly are you talking about?

I bought a walmart bike and picked it up in a sealed box. I had to mount the front wheel and the handlebar.

This is not something that takes a lot of time. Are you saying the front wheel comes off because the nuts were not tightened?

A hundred dollar wallmart bike is a hundred dollar wallmart bike. They are not good. They are at best OK. In 10 minutes they are "assembled" right out of the box.
 
Here is a pic of the jug notice how a large chunk is gone
I can't find it in base although I managed to find and pull the retainer pin
could the rest have turned to powder?
 

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I would split the cases and make sure nothing else was inside, since you have to order parts anyway add gaskets to the parts list.
 
I agree with Greg58; it's imperative that you make sure the case is clean. Also, if you're on a budget, that jug IS salvageable. I have had similar damage. That chunk and damage are not in the jug's combustion-zone. Lightly grind and polish down those rough areas and try it out.
 
It has been my experience chunks like that tend to stay in the bottom end. Split the cases.
Even if it somehow disappeared or was ejected, your mains will need to be cleaned anyway. May as well do it right rather than HOPE you found all the damage. Be a good time to do some transfer porting with the case halves and jug disassembled...(:))
 
that chunk is wedged somewhere or you would have a hole in the block ... that is a HUGE bit to be bouncing around in the bottom end
 
thanks all I'm going to do that next week. have a roof to do right now.
but did get parts in, What I was asking, stating, wondering was that this cast
alum. under pressure can just disintegrate into powder and be shot out exhaust.
I'll find out when I open it up.
 
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