From:David e-mail:dklein61-A-gmail.com
Subject:RE: RE: engine locks down and refires Date:Tue Jun 9 11:58:09 2015
Response to:20539
Thanks I'll check it out.

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Let's assume you don't have a big piece of cardboard blocking the airflow over the engine or a lot of broken fins. Your bore to piston is too tight and it locks when the piston expands in the cylinder. Take it and have the cylinder honed(not bored)another .001" to .0015" (that's a thousandth or thousand and a half inch oversize). The easiest way to tell a 125 from a 165 is if the spark plug is set at an angle it's a 125. If it stands straight up it's a 165. You said 50+ miles an hour? Probably a 165.

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New here and with the hummer. I have a 59 and when I ride for a few miles at 50+ mph it will lock down and slide the rear tire. I can immediately pull the clutch in and kick it and fires right back up. If I ride at lower speeds it runs fine with no trouble. Any ideals? I run the 25:1 oil mixture. As I read thru the site it looks like years of experience here. I have already used a lot of info from this site to get it running. Thanks to all !! Also, how do I know if it's a 125 or 165 motor.

Thanks for everything guys
David