The only problem i have ever had with my PE 175X was with the carb . The slide locating pin came adrift from the body of the carb and got sucked through the motor . Didn't cause any damage (its aluminium ) but wedged itself between the crank web and the crank case giving the impression that the motor was seizing. Finished a race on it no problem but when i went to stsrt it it wouldn't start , the slide had turned in the carb . kicking it you didn't notice the extra resistance but when turning it over by hand you could feel the binding . Pulled motor down expecting the worst , and found the culprit sitting under the crank web .
Reassembled it fitted new carb and its been good as gold ever since
Heres Brad 090 doing things with it that made the enduro purist blush at the Johnny Old