flat-top vs oem pistons

[munki63]

Im wondering if there are any gains in using the dome(oem) vs flat-top pistons, im guessing the compression would go up a little if your using flat top.

Also what do guys do for heads when they bore +7(88) I realize you need big bore sleeves

 

[SUPERTUNE]

R&D came out with the DOMINATOR flattop pistons (84-86.5mm) made by Wiseco to their spec's for the big bore SuperStock class with their special sleeve for them. The R&D piston was the same piston CD (compression distance/deck height) and 2 degree dome top as a small pin Kawasaki 750, but with improved Yamaha skirt design.
They are much shorter piston than a 701/760 tall piston, with this in mind you need to mill the cylinder block shorter, sometimes all off the top and sometimes a combination of both the top and bottom machined depending on the desired port mapping and sleeve used.
One benefit is with a shorter piston you save weight, 2nd with the custom piston the ring pins are moved away from ports so they can made wider to gain more port area.
This has been covered here before, but wouldn't know how to search for it.
It's really not all about it being just a flattop because so many other rolls can play out in gaining or losing performance.

 

[SUPERTUNE]

We make all our own heads and domes to match to our billet cylinders for 88mm and up bores. ADA also does offer a big bore dome cut in the std 701/760 head shell to use the 951 Seadoo dome or blanks that they can make custom to fit your flattop piston.
Custom sleeves with big o.d.'s are needed for this big of a piston as well.