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Well after a long and busy summer I finally have some time to work on the bike again. The head is in having seats cut for my fresh new valves and cylinders have gone in for boring. My machinist called today to ask me what the piston to cylinder clearance ought to be. I haven't a clue. :roll:

The only numbers I can find that make sense to me in this matter are the following...[attachment=0:1vanyix1]Picture 1.png[/attachment:1vanyix1]

Does this mean that piston to cylinder clearance is 0.03 - 0.05 mm? considering that standard bore is 70mm and standard piston diameter is 69.95 - 69.97mm??

That being the case and I am utilizing 3rd over pistons the numbers should correlate as bore = 70.75mm if pistons are 70.72mm???

Thanks in advance fellas... ;)
 

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Hi,

A little late, but the clearance should me as small as possible within the limits, so 0,03 mm.
The bore should be bored to match the piston, so forward the pistons to your machinist, and he can bore the cylinder to spec for the matching piston.

I prefer to have a clearance between 0,01 and 0,02 mm, witch is no problem regarding the use of modern synthetics,

Jensen
 
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