Which Pistons

rad · Post by **rad** » Sun Jun 24, 2007 5:41 pm

Just bought a KR1S track bike. Has a Stan stevens SS400 engine that requires a top end. Currently running on Kawasaki standard pistons, B size ones i think.
I have heard it is better to use modded TZ pistons as they only have one ring so are quicker to run in and don't suffer from the ring spinning like standard ones.
Does anyone know of the best/commonest pistons to run and where the best place is to buy them.
Also does anyone know how to raise the ride height as the spannies scrape in corners.

Cheers!!!

mgtkr1 · Post by **mgtkr1** » Sun Jun 24, 2007 6:49 pm

my bike has tz pistons(26j) and fit straight in but top get the best out of the mod you should have the head revised to give correct shape/squish etc. size is 96 and can be used on a stock head but the squish is reduced slightly due to taller deck height though that isnt a problem as the std clearance's are on the big side! other tz pistons are very diffrent requireing machining the base gasket face as there shorter, 2mm i think but are'nt certain. these are 4dp, there are more, best have a look on team sparrow as that site is like alladins cave regarding kr race related info. sounds like you have a bolloxed rear damper, unless you have a 17'' rear without the appropiate mods. the mod is to reduce the length of the tie rods by 6mm, rc46 has or is having some made from bdk out of cnc alloy with a lovely anodised black finish. there is a load of rear shocks around for the kr with loads of adjustment, need one myself! rgv is the wheel to use on the back if you cant afford dymags(like me!!) just involves spacers and a sleeve that fits inside the rear as the spindle is larger on the rgv, one of the best things to do to a kr as it means you can use decent rubber, which in turn means quicker laptimes aswell as been easy/cheap to do.the std pistons are fine these days btw, the reason i use tz pistons is the porting i have means thestd ring peg sits in one of the ports. be carefull though as thers still some ''old stock'' pistons that suffer from the dreaded loose ring peg syndrome, not sure of the part number.

rad · Post by **rad** » Sun Jun 24, 2007 8:01 pm

Cheers for that.
Is size 96 refering to the piston or head type?
Does any 17" rgv whel fit?

Thanks for the assistance!

the-elf · Post by **the-elf** » Mon Jun 25, 2007 11:50 am

Yep any 17" RGV. which from memory is VJ22 onwards. The older VJ21 had an 18".

mgtkr1 · Post by **mgtkr1** » Tue Jun 26, 2007 2:34 am

piston size is 96, its a thing that normally only applies to tz's rs's as there pistons are changed so often that the sizes go up as the plating wears, i think? anyway i use 96 size as instructed by the very knowledgeable mj, think this goes for all kr barrels/tz piston combo's. elf is right, you want the vj22 rear hoop as the earlier vj21 is the same as a std kr rim at 18''