this ones easy

[AIRICCC]

i took my cylinders to a local shop to get bored... i have pro-x pistons 83mm.. i think thats .08 over.... they need to know what kind of clearance i want... i didnt know what to tell them, but i said i know how to find out...

 

[hangtime]

I think it .05 but someone who knows for sure will prove me worng

 

[Mouthfulloflake]

the PRO-X pistons shoudl come with that info?

in my opinon, if the shop is asking you that, Id find another shop.

they should KNOW that sort of stuff, or at least know how to find out.

granted, its not such a big issue with cast pistons, but still, they should KNOW that stuff.

 

[Metal4130]

On my 650 it says in the YAMAHA manual that the MAX limit is .1mm and the usuall is .080-.085 Again if anyone knows different they could be right too.

 

[Mouthfulloflake]

piston: 80.925-80.950mm clearance 0.080-0.085mm

Ring endgap: 0.2-0.4mm

from a quick search at pwcyesteryear


groupk has some info also...

Piston Clearance - It's common for new 701 cylinders to have as much as .005" of piston to cylinder wall clearance. (set-up clearance is .003" - .0035" ; wear limit is .007"). On any racing or high output recreational packages, we recommend set-up clearances of no more than .004". Engines intended for moderate recreational use can easily live with .004" - .005" set-up. Piston clearance inspection is available on request, and cylinder boring (using pistons furnished by you or us) is available in all oversizes. Since Yamaha only offers only two oversize pistons, boring beyond second over will mandate the use of Wiseco pistons. In any case, all ported cylinders are honed before return shipment.


and... Even more contradicting info..


http://www.pwctoday.com/showthread.php?t=68668&highlight=piston+clearance

 

[AIRICCC]

that answers my question, no more than .004...
the shop does dirtbikes mainly so maybe that has something to do with it... i think he also saw the porting and assumed that i had a special request for clearance... i think ill just tell him no more than four thousandths...
paul, got any advice?

 

[douglee25]

I'd also go with around a 0.004 to 0.0045 clearance with ProX. If you were setting up Wiseco pistons, I'd go larger at about 0.006 to 0.007 because they tend to like a bit more clearance than cast pistons.

Doug

 

[Rickster]

Waterfreak just had my 1100 engine done, and he went .005 clearance.

Much better than the .025 that the pistons had before the rebuild!:banghead: :banghead: