Bore Bigger or Not??

[vmf214]

My jug is on its way out to be plated. What harm is there in just going to the 70mm bore? Should I just keep it stock at 69? The cylinder is in good shape with no real flaking or scratches. This rebuild will add a RB Designs carb with Ron's head work done as well as a V-force reed cage. FMF rev pipe already in place and a Hinson basket ordered from FRP.

Thanks -

 

[glad2ride]

I can only remember happy comments on it, but they may have had Eric Gorr porting to go along with it. I say bump it up to 223. :-)

 

[adam728]

If it doesn't need it I see no reason to bore it out 1mm. Power gains will be minimal, you'll need to grind the powervalve for clearance, and port timing may be slightly altered as the ports do not exit the cylinder at perfect 90 degree angles. Plus if you screw it up later it can just be bored and replated, as opposed to welding then boring and replating, which I am sure costs more.

If you want a little more boost just have it ported. I run FRP porting, head mod, carb bore, FMF rev pipe/Turbine Core II and Boyseen or FMF reeds (feel the same to me). It rips, and it's stock bore.