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Heylo new to this forum.

So, bought a junker and boy was it more of a junker them I thought lol.  I got it running good and noticed the head gasket had failed (1994 yz125) and it's leaking coolant into the cylinder/ engine.  So I decided to fix that. Upon removing the cylinder I found some decent scratches on the piston, glazing, and blow by but the cylinder looks decent no scrathes.  The cylinder is sleeved and the bore is 55.8mm and the thickness of the sleeve 1.6mm.  I want to get a 56mm piston for it but I know I'll have to bore it to over 56mm. Probably 56.2-56.5?  My question is this. What's the minimum thickness the sleeve can be before having to get it resleeved and with a 56mm piston do you know what the piston to wall clearance should be on a weisco piston part number pk1703?   Basically do i have enough sleeve wall material (1.6mm) left to take it from 55.82 to 56.5 with out a problem, or can it be bored a lesser amount  then 56.5mm and still make piston to wall clearance? Thanks.

 

PS. I will happily answer any questions to the best of my ability.  

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A shop that installs sleeves could give you a better answer over the phone. I would call PowerSeal USA and ask for technical support on sleeves. You will probably talk to Chris. 

1-484-921-5121

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 thanks I just got back from a shop.  Wasn't the best news but wasn't the worst. Given the amount of wear and the amount that he'll have to bore out, I'll need a cylinder that's at the very least 56.2 mm to 56.5 mm, Sonu question does anyone know where to get a 56.5 mm piston LOL. I checked Wiseco and random Google searches but no dice also thanks for the quick replies I appreciate it.

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How about a new sleeve in that old jug? 

Edited by 2SYZDOC
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The stock bore on a 1993 YZ125 was 56mm. The 1994 to 1996 YZ125 was 54mm. The difference in stroke kept both models at 125cc. Before you commit to any $, you should check the VIN to confirm your model year. A 1994 yz125 with a 56mm piston is an aftermarket mod, and displaces 134cc. 

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55 minutes ago, 76xtdrvr said:

The stock bore on a 1993 YZ125 was 56mm. The 1994 to 1996 YZ125 was 54mm. The difference in stroke kept both models at 125cc. Before you commit to any $, you should check the VIN to confirm your model year. A 1994 yz125 with a 56mm piston is an aftermarket mod, and displaces 134cc. 

Good call, but I would go off the engine number at this point. 

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