650 engine mods, advice needed

So I have to pull the head on the 650 (see my thread in chit chat under damned red tube for the reason if you'd like) to get some garbage out of the cylinder. I happen to have a machinist friend who is willing to do some head work while it's off. What I have in mind is to mill the head (just don't know how much is needed or necessary other than just dressing the gasket surface, polish the intake/exhaust runners and match the intake runners to the intake boots. The parts I already have laying around are: 26mm carbs, Kerker 4into 1, GPZ750 cams and an oil cooler. I need to change the cam sprockets on the cams to the old style cam chain sprockets but I have those too. What I need to check to see is if my buddy has a set of 750 pistons and cylinder. I want to use my 26mm carbs so I'm thinking I need to keep the 650 head and not a 750 head. Advice and opinions are welcome from anyone who has done such mods.

When you start matching those intake ports try and transition/funnel them down as you go further into the port before hitting bowl area then try to just clean up the bowls without changing the shape a lot.
Its more important to get efficient flow from one end to the other than to make huge cuts.
Im not sure about the exhuast ports on a 650 head but ill put up an old picture of exhuast ports on an early 81-82 gpz1100 head I did years ago since Im having trouble loading pictures of new work on computer. :sick:
As far as milling head Id just make sure its flat,if you want to bump compression up I prefer to have bottem of cylinder milled to zero out the deck on highest piston.

A number of years back Colin Firth aka Reborn650 up in Sudbury Ontario turned a 650 into an 810 with GZP750 cams and 29mm smoothbores. That was/is an awesome bike and I had the opportunity to see it one summers evening. It might take a little searching but he had a big long thread which I always though of as writing the book on 650 mods.

IMHO best bang for the buck would be just find
a 750 motor to start with.
My stock 83 gpz750 motor with VM29's go's low 12's
spinin the tire.

Does a 750GPZ head take the same intake rubbers as the earlier 650/750? I was thinking it required a much larger manifold.

Mellvis wrote: Does a 750GPZ head take the same intake rubbers as the earlier 650/750? I was thinking it required a much larger manifold.

No they will not, the bolt patterns are different. However you can get the GPZ750 manifolds onto the KZ650 intakes by elongating the holes. The KZ650 manifolds will not fit the GPZ750, to small. The earlier KZ1000 manifolds will fit the GPZ750 intakes which will allow you to put on the VM28 or VM29 carbs onto the GPZ head.

When I did my motor swap I used a chain saw file and
sloted the bolt hole's on my 650 boot's to fit.

When did the 29's I called Robert at Z1 ent.
told him VM29's and he sent me some boot's I filed hole's
and their a deadnut match to the port.
I'll go get a pic.

.010 inches is good to clean up the head.
Remember, "Nothing Replaces Displacement"

Remember the more you mill the head the more your cams get out of time. My 650 with Yoshimura 716cc big boar head work Yoshimura cams 29 smoothboars and a Yoshimura race header. My bike runs 12.20's with a slick but no wheelie bar.
Mark

Mark, I don't understand how moving the cams toward the crank will change their timing. Ignorance maybe, but I wold think that only the cam chain slack would change and the slack adjusted would cure that. Milling the head only changes one dimension, the distance from crank to cams, or is there something I don't realize? Oldschoolz, do you know of a way to calculate how much to remove from the head to obtain certain compression ratio changes? I figure with stock pistons it's not going to change the compression much to take .010 or .020 off of the head. Zukedave, The picture would be great. I plan to run my 26mm's so I was thinking manifolds for maybe a 1978 KZ1000. Do you know if they are the same bolt spread as a 650 or will I likely have to notch them as was described?

Thanks to everyone so far, these are the questions I didn't know to ask.

Well as the head is lowered the cam chain gets slack and it can only be taken up with the tensioner and the cams roll back a little. there's no way to remove the slack for the exhaust cam. And 1000 manifolds do need slotting to fit a 650.
Mark

What Mark said.