Engine ballance with overbore pistons?

I am looking at an overbore kit for my 650 kaw. Quite a few people on this site have done this to their bikes. I was wondering if you should have the engine re-ballanced? Or are the wiseco pistons the same weight as OEM?


In another post it was suggested that I find 750 cylinders and install an overbore in those to bump my 650 up to 810cc.
Again are there ballancing isses here for those who have done this?

I understand that in-line 4's with the 1-4,2-3 firing order cancel a grate deal of vibration as long as the rod/piston wieghts are equal cylinder to cylinder, but other than that what other ballancing issues that come up from installing larger pistons?

In a related question does anyone have the compression ratio of the 700cc wiseco overbore kits for the kz650?

Thanks all

I wouldnt worry about it, the aftermarket big bore pistons will be pretty close to the same weight. Yould have to compltely tear the whole motor out to balance it and then you should get the crank welded, big work & money

Pistons do not have to be same weight as oem, as long as they all weigh the same. Four cylinder inline cranks are self canceling, so if the crank itself is in balance, what ever you bolt to it will still be in balance it their weights are the same.

Jay

Thanks thats what I thought. Just asking the "gurus" for good measure. I only want to do this rebuild once.

Another related question, are main and rod bearings avaible for the kz650's, or do I have to sift around for NOS parts?

I'm not suree if you can get them at the Dealer or not, I've seen them on eBay now and then. Now you'll want to plasti-guage everything everything and get the same ones as long as everything checks out. The bearings aer only a little bit biger or smaller by 2 or 3 thousants and are used for adjusting your clearence's.