cleaning out the crankcase

[dfilups]

My son has a 1991 KX125.  We were getting ready to replace the piston because of low compression when we got several inches of snow.  What is the first thought for a 16 yo and his buddy?  Lets get the bike out and ride in the snow. Anyway, they were riding and when they stopped to warm up the motor seemed to be seized.  We took the upper off and found the piston is missing a piece.  The crank will swing back and forthe in the case but sems to be hitting the broken off bit when the piston arm reaches the bottom.

Is there a way to get into the crankcase without breaking the case in half and doing a complete rebuild? Can we get in there and pull any parts out of the crankcase?

Thanks

[Foxx4Beaver]

there's a SLIM chance you could drain the oil and get the pieces out, or even getting a pair of hemostats in between the crank halves to extract them...but, you'll never get ALL the debris out...soooooo, if it were me...I'd just suck it up and tear it right down, and replace all the bearings, the piston...cylinder probably needs a replate anyhow.
Take the time and do it right the 1st time...or you will be tearing it apart again.

[treedodgingfool]

A broken-off piece of piston is an engine-ender.  No safe way around that short of splitting-cases, inspecting the cases carefully for cracks (the force of that piece wedging against the crank lobes & pressing against the cases may of very welled cracked them). Not only that damage, but bits of aluminum could be in the two oiling passage, knicked-up the crank seals, impacted in the main bearings or lower-connecting rod bearing.  For a piston to have enough slap to break-off a skirt, the cylinder I'm sure is well over due for a replate and on a 125, the lower connecting rod bearing is most likely not far behind either.  Sorry for the bum news.

[dfilups]

Yea,  I knew the answer was not going to be what I wanted to hear but at least I have a shop, a bench and a friend that knows more about engines than I do.  The bonus is that we homeschool and can use this as a auto shop credit.