TOPIC:

I have a1981 kz1000j bottom end putting a 1981 gpz1100 jugs on with my 1000 j head. Would it benefit me to put the gpz1100 cams in or leave the 1000j cams in?are they the same lift? I'm pretty sure I'll get more compression with the j head cause of the smaller chamber?and I was going to leave out the base gasket to bump the compression. Some help here did any body do this !!!!!

Sounds like an interesting project, somewhat similar to what I did early this year.
I asked lots of questions, and found much assistance here...very knowledgeable people, other than myself. If not for such advice, my project would have remained a passing thought, and never been attempted. I know my limitations, but these folks helped me exceed them and achieve what I hadn't thought possible.
Be patient, and don't rush anything...especially with the torque wrench.

If you leave out the base gasket, how will you prevent oil from squirting everywhere?

No base gasket I'm using yamabond or some good permatex. I did this on a 750 Yamaha with a 900 jug. And got half a point compression. Lol it worked for that project anyway. I'm just unsure of the j head on the 1100 jugs.

Not worth it.
Steve

I've heard before of using sealant instead of a base gasket, apparently it worked for the bored out 550 racebike. Whether it is good long term for 10k plus road miles as a minimum I don't know. Your 0.5 difference to CR sounds about right, I'm probably going the opposite way on my high compression pistons with either a thicker or stacked base gasket.

Your combustion chamber volume and cam lift can be measured directly. Verniers on the cams to measure the lobe height against base circle measurement. Chambers done with a drilled glass or perspex square, a cc syringe and spirit level - check all four.

These bikes often gets bits mixed around or modified over the years so I'd sooner rely on direct measurement rather than whatever the service manual specs are.

I'm pretty sure I can do without the base gasket. I think there's just enough clearance to run it but I'll check it out.I'm just not sure what cams to use with the 1100 jug or should I just find a gpz 1100 head. I know the gpz head has a bigger chamber so I was avoiding it. I was just trying to get some compression the cheep way.and good cams are expensive not enough in the budget for port work but I got new springs.

Wouldn't it be easier just to skim the head? I'd measure your actual combustion chamber volumes first, easy enough.

Don't go crazy on increasing CR, the returns are disproportionate. From the z900 to late GPz1100, wringing every last bit of power out of it but trying to keep it reliable, kawasaki kept the CR fairly modest.

I think the z1000J3 cams may be the same spec as the later GPz11, with a massive 300 degrees duration. There are details in the FSM regarding identification grooves on the cams. I have these in my ELR, they are very peaky - think two stroke powerband sort of top end rush, really arm wrenching, if that's what you want.

Thanks for the info !!!!! I just got the 1166 big bore kit now also !!!!

Ok I'm not sure what comes factory in my motor or if i got the z1000J3 cams ? Do those cams your talking about come in the 1981 kz 1000 j?

I have done this, used a head from a GPZ1100 with the cams on a J motor bottom end, straight fit, didnt change anything and it was great.