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So i pulled the head off the motor on my 2000 ZR700 (7,900 miles on motor) today to find out what was wrong with it. initially i thought the piston had hit the plug due to piston slap or a bad bearing...well, i was wrong.
from the looks of it, the top ring rotated in the groove and caught the transfer port. causing the ring to bend up slightly and break off a good size chunk of piston. there is absolutely no damage to the motor other than the broken piston, the head is fine, the cylinder is perfect, even the top of the piston has almost no marks from the chunk of aluminum ratting around in the cylinder.
not only does it still run, but it has 98 psi compression in both cylinders and i drove it 35 miles back from when the plug gap had gotten pushed closed by the broken off piece of piston. i just threw a new plug in a drove back.
this old 700 twin really is a tough motor.
now for the pics.
from the looks of it, the top ring rotated in the groove and caught the transfer port. causing the ring to bend up slightly and break off a good size chunk of piston. there is absolutely no damage to the motor other than the broken piston, the head is fine, the cylinder is perfect, even the top of the piston has almost no marks from the chunk of aluminum ratting around in the cylinder.
not only does it still run, but it has 98 psi compression in both cylinders and i drove it 35 miles back from when the plug gap had gotten pushed closed by the broken off piece of piston. i just threw a new plug in a drove back.
this old 700 twin really is a tough motor.
now for the pics.




