750 cams in a 650?

See a lot of mention of 750 cams in 650's, are they a perfect drop in fit? Any other changes needed? Any problem with valve to piston clearence? Will be ajusting valves in near future and figured if cams out anyway why not pick up a couple ponies. What years are recommended? Is it JUST that easy?

if your kz650 uses a hyvo cam chain its a straight up bolt in mod. if your kz650 uses the old roller style cam chain, put the kz650 cam sprockets on the kz750 cams, and then its a bolt in mod. gpz750 cams also bolt right in with the same rules, and are a bit better then the kz750 cams, but they dont have the worm gear to drive the tach cable, so either you wont have a working tach with the gpz cams, or will need a different one. I think 83-84 were the best yrs of gpz cams.
dont forget to rejet your carbs as they will be running lean due to the hotter cams;)
Scott

Post edited by: 77KZ650, at: 2007/01/02 23:44

Don't forget that you will need to re-shim it to keep all the clearances correct, whichever cam you use.

I believe that early 750 cams kept the worm drive for the tacho but at some point they lost them . My '91 Zephyr cams didn't come with a worm.

That said, if you need the worm drive then you could just change the inlet cam on its own leaving the 650 exhaust one in its place.

KZ650 has the worm gear on the exhaust cam, and its cams are the mildest
KZ750 has the worm gear on the exhaust cam, and is an upgrade over the 650 cams
GPZ750 doesnt have the worm gear on the exhaust cam, and these are the best cams to use besides larger aftermarket cams
Im not sure if the 750 Zepher cams fit or not

Scott

77KZ650 wrote:

KZ650 has the worm gear on the exhaust cam, and its cams are the mildest
KZ750 has the worm gear on the exhaust cam, and is an upgrade over the 650 cams
GPZ750 doesnt have the worm gear on the exhaust cam, and these are the best cams to use besides larger aftermarket cams
Im not sure if the 750 Zepher cams fit or not

Scott

750 Zephyr cams are the same as the KZ 750 in every way except the worm drive

I think I read on another post that the '82 GPz750 cams were an upgrade to the Kz750 cams and they used a mechanical tach aka worm drive ?
Would the ZR7-s cams work in a 650 as well? Disregarding the lack of tach drive of course.

Cool thread!

regards to all New Years survivors:sick: :woohoo:

Not looking for a huge boost in power, I think the standard KZ750 cams would perk things up a little bit, I like reliability also. Anybody running the KZ750 cams? What difference did you notice?

Hey Bluemeanie - I put the Kz750 cams, Gpz 750 intake valves'springs into my 810 motor. I also retained the Kz650 head which was ported, polished and milled 10 thou to clean up the mating surface. The cam sprockets from the 650 cams bolted directly onto the Kz750 cams.

At the same time I went with bigger carbs, Dyna coils and electronic ignition, so it is really tough to say how much the cams alone upgraded the performance.

I would be willing to bet that the cams will get you a few extra ponies but don't set your expectations too high. If the head is off the motor a little porting will help you find some extra power. This is an easy and inexpensive upgrade that will assist in breathing.

Cheers-Colin Firth-Ontario Canada
1977 Kz650 Custom - 810 Wiseco kit, Wired George Mikuni 28 Smoothbores and lottsa go-fast goodies tucked away inside. Miss January on the 2007 Kzrider.com calendar.

You could benefit by fitting an entire 750 cylinder head as well as the cams. That way you gain the larger valves as well.
As Reborn says a mild port clean up would help as well. Don't remove too much material for a 650 though, the stock ports are big enough. Just take out the lumps and bumps