Piston to cylinder fit?

[joelyons50023]

I am going to be getting my cylinder bored out to fit stock venture pistons in my bike and was wondering if anyone knew what the piston to cylinder space was supposed to be. Found a shop that will bore and deck my case for $300 , not bad I think. They use a cool CNC machine to do most of their work. Here is their website. http://www.midwestcylinderhead.com/

http://www.youtube.com/watch?v=zuwjrEKXJmU

 

[one2dmax]

.004 piston to wall clearance. Note: Clearance numbers are obtained from measuring the largest diameter of the piston, typically at the bottom of the skirt. All measurements should be taken 90 degrees from the pin centerline.

 

[joelyons50023]

Thanks very much Sean. Is there any difference between the 1200 clearence and the 1300 clearence?

 

[one2dmax]

Not enough to worry about.

Sean

 

[joelyons50023]

is that spec for cast or forged? I found this but it may be wrong idk. http://www.scribd.com/doc/17052931/1986-1993-Yamaha-Service-Manual-XVZ1300-Venture page 115

 

[one2dmax]

Wow, they got the piston pretty tight there. The nice thing about cast is they hold their size better normally without the thermal expansion seen with forged. Not sure i'd go that tight but that looks like the right spec to me. You might see if anyone has a venture book with supplementals that can make sure they didn't change the spec after the first book was released. They never change the spec on the main page but add a correction page to the front in supplementals.

Sean

 

[joelyons50023]

Piston Clearance = C-P:

0.055 0.075 mm
(0.0022 -0.0030
C: Cylinder bore P: Piston outside

From the vmax manual that I have.​

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