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199A Rebore


blutaco
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The 199a I'm restoring has evidence of a cold seizure so a full top end overhaul is in order.

I'm looking for any information or advice on conducting a rebore. Not sure if it's a plated bore or if a straightforward rebore will suffice.

Any help welcome!

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The T2+ indicates final cylinder diameter after boring. If using a Mahle piston (oem) , then these markings are critical as they need to be used to get the proper final bore size. If using a wiseco piston then follow their specs...... And then add another 3 thou to prevent cold seizure.

Steve

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Hi Steve ve

Thanks for replying. It is the original Mahle piston. I bought the bike when it was 1 year old from a chap in Oban. I'll buy the new kit from Inmotion. Is there anything in particular I need to advise the folk doing the rebore?

John

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I'd have to look at my manual to determine the final size but 1.7 is in the ball park. The mahle pistons work just fine at that clearance and so long as they are properly warmed up there won't be an issue. Wiseco pistons have to be run quite loose to prevent cold seizures and even at that they'll still seize at some point. In 25 years of being a professional mechanic I've never seen a wiseco piston not seize. Stick with mahle always if you can

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I always bore mine to 1.5 thou and have never had a problem, always very careful during run in. A friend had his bored and thought it was nice and quiet until we went riding together and then realized his brand new rebuild was quite noisy. To cut a long story short, he pulled it down and got the piston ceramic coated [cost about $40]  The ceramic coating people can alter the thickness of their coating to suit, and after reassembly the motor was a lot quieter and ran great, fairly cheap solution.

Cheers Greg

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Nothing new for me to add only my own  opinions, Mahle whenever I can get them, nice that 350 pattern

pistons work wherever, we have at present 85mm piston well worn in M199.

Mahle pistons @ .0015 thousandths clearance, (finding a good bore man very important).

When forced to run a forged piston .003 thousandths and let her rattle until warm , then OK but not as nice 

as a Mahle.

Sadly getting near impossible to source a Mahle here anymore.

Larry

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