Overbore and powervalve clearance questions

[Jes_KX5]

I was thinking about overboring 2mm since I need the cylinder replated anyway. If I do this overbore, with there be any clearance issues with the powervalve or reedcage? Also, is the extra 22cc (total 522cc) worth the extra $40 for the overbore and 2mm larger piston? How will jetting be affected?

[1alldave]

There are no issues with powervalve or reedcage clearance. You will need to have the head machined for the new bore. The stock head gasket will not work, but the Cometic gasket has the proper diameter. It makes the motor a real grunter if done right (proper porting) As far as jetting, every motor wants something different. If you do no other mods, you may end up leaning down the main a tad.

[Rick]

One thing I would consider is the price comparison for piston replacement.  I suspect the large bore is a pricier piston.

Just a thought.

Rick

[1alldave]

It all depends on what you want. The Weisco piston kit will cost you around $120 but it comes with everything. If you want max motor it is the way to go. Mine makes power down low like a 4 stroke, and has some serious mid and up bark. If what you want is a simple rebuild and piston availability at your local Kawi dealer, stick with a replate at the stock 86mm bore.
Dave