Hi all, A friend of mine just bought a 03 gas gas txt pro, the engine was knocking so we pulled the cylinder, there was quite a bit of damage to the piston, cylinder is ok.Bit of play on the little end bearing and pin but bottom end is ok. The other problem is the crank is very tight, to the point that we cannot spin it by hand and have to use the kickstart and its noisy when you spin it, not grinding but a rubbing noise. Any suggestions? We pulled the ignition cover and there is no play in the crank,bit of normal end float but nothing up and down.

Hi all, A friend of mine just bought a 03 gas gas txt pro, the engine was knocking so we pulled the cylinder, there was quite a bit of damage to the piston, cylinder is ok.Bit of play on the little end bearing and pin but bottom end is ok. The other problem is the crank is very tight, to the point that we cannot spin it by hand and have to use the kickstart and its noisy when you spin it, not grinding but a rubbing noise. Any suggestions? We pulled the ignition cover and there is no play in the crank,bit of normal end float but nothing up and down.

From your description, I'd say the engine needs to be disassembled and inspected. Sounds like serious engine damage.

Jon

it sounds like the main bearings, but you say there is damage to the piston? if bits have come off , they may be part of the problem in the bottom end. By the sounds of it its seized at some point. I does sound like a full engine strip.

The piston is only grooved, no chunks missing, ya we have the engine out, clutch is off and still very stiff so must be mains, don't think previous owner was too big on maintenance going by the state of the engine and the air filter,he liked to ride it on the beach by the amount of sand in everything. We'll get her sorted out and running sweet again, will be splitting the cases in the next couple days so will post our findings.

Engine running smoother now, new main bearings and piston.