Topic: Piston kits for K7 750

[Catfish]

G'day all, I'm trying to identify piston kits on the market for my k7 motor. Basically its a project bike and I've just pulled it down and there appears to be some significant corrosion in one cylinder, so i need to look at oversize or big bore options. I'm not hung up on taking it out to 836, oversize is fine ( it seems to be the standard 61mm at the moment).

From my research on the net, i cant see any piston kits specifically for the k7. Closest i can get is a CycleX oversize kit that is for the earlier k models, but they say you can use it on k7, you just have to note that they dont have a dome like the original k7 pistons. Any views on this? And does this mean i could fit any oversize kit designed for the earlier k models?

Finally, i would appreciate any info on where else to find kits suitable for the k7 apart from CycleX.

Many thanks in anticipation.

[Restoration Fan]

You can use any of the 750 or overbore 750 piston kits.  It doesn't have to be specific to the K7.

[Jerry Rxman Griffin aka MuthaF'er]

Yeah just as long as you dont use F2/F3.

[drumstyx]

Are you guys saying one can use the pistons listed here: http://www.vintagecb750.com/products/4/engine/75/pistons-ring-sets on a K7 or K8, even though only listed for K0-6? That'd be pretty awesome.

[Catfish]

Thanks all for the replies. Thats what has been confusing me, they never say (apart from CycleX) that they fit k7-8.

[madmtnmotors]

There's these:

http://www.ebay.com/itm/131588210647?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT


or these:

http://www.ebay.com/itm/131588211611?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The CycleX pistons are the same flat tops as above, and per CycleX:

"Note: These pistons are manufactured with the 69-76 dome height. 77-78 K models had slightly smoother combustion chamber so 77-78 K model pistons had a slight dome on the piston. Because the dome height on 77-78 K pistons is very small, our pistons can be used without power loss issues."

I would agree, that you won't lose power, but the power gains in a 77/78 engine would be less than the power gained in a 76 or earlier engine.

New pistons and rings will perform better than old pistons with worn/leaking rings. You will have less compression than stock, but not much, and it will run well.

Slightly lower compression will be exerting less stress on all your other 40-year old engine components as well. With CycleX 4th over pistons in my K8 I can run the 1/4 mile in just over 14 seconds without thrashing it too hard.

[Catfish]

Thanks Madmtnmotors, i had seen those ones and i daresay ill end up getting one of them. I think next step for me now is to put it in to a shop to get an opinion on how much will have to be taken off, so i know which kit i need.