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Old May 18th, 2017, 05:44 PM   #1
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Name: Roger
Location: Mitchell, South Dakota
Join Date: Apr 2014

Motorcycle(s): 1978 Z1R, 1999 EX250

Posts: A lot.
MOTY - 2018, MOTM - Oct '16
Pulling the head

The '99 was down on power at the track last year compared to the other 250's in our group (6 total) so I pulled the jugs and found huge rust pits in the cylinder walls. (it had been sitting for some time before I bought it) Replaced the pistons and cylinders with the ones from son's blown motor, and it ran much better (best it's idled since I've owned it). This spring was tuning on it and it just didn't seem right compared to the other two I have, still down on power and running a little rough. At this point I did a compression test and it was at 160 lbs. on #2 and 100 on #1, hooked the air to it and the exhaust valves where leaking so much you could feel the air coming out of the muffler and the intakes leaking enough you could hear the air coming out of the carbs. Pulled the head again and had the valves sharpened and seats ground, now it has 180 lbs. on #2 and 170 on #1 and I think it's the strongest running one of the bunch now.
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Old May 18th, 2017, 06:19 PM   #2
Triple Jim
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Name: Jim
Location: North Carolina
Join Date: Jul 2016

Motorcycle(s): Ninja 250

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MOTM - Oct '18, Aug '17, Aug '16
It's amazing what a good piston-cylinder seal can do. Enjoy your "new" engine.
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