gpz 750 cams question

i made a deal with someone for gpz 750 cams he wants.
i was over at a friends house tonight to get the cams from him and these cams have a tach drive on them.
the bike is a 82 gpz 750 and i pulled them out of the motor myself.
the last set i sold to a member here were for a 84 750 and had no tach drive.

does anyone know if these cams are different?
is there a possiblity these are nor orginal cams?
they have the r1-r2 numbers on them.

i just don't want to screw a member.
what year did they switch to the electric tach?



btw, we are stripping a complete 82 gpz 750 so please contact me if you keed any parts.
it was a complete bike with all bodywork.
we also have 2 other sets of gpz cams .
and a ton of other gpz parts.

what shape is the body work in?


:whistle:

perfect bodywork.

do you know amything about the cams?

I'm reasonably certain that 83 was the first year of the electronic tach, and I think the 83-85 cams have the most lift and duration.

I just checked the manual, and it says the 82 KZ750R (GPz750) used the same cams as the KZ750E and H, only 83-85 ZX750A1-3 had the cams with more lift and duration (and no tach drive).
The GPz750 Turbo uses the same cams as the KZ650.

Post edited by: steell, at: 2007/10/16 23:47

Steell is correct.

Anyhow, who needs a tach unless you are setting your idle speed? I shift when it stops pulling:)

Cheers-Colin Firth-Ontario Canada

The easiest way to identify the real GPZ cams is to just measure the lobeheight.
Take a look at the following pic:


Just use a vernier caliper to measure the complete lobe on the cam.
If it is 36,15 mm (1,424 inch) high, you have the wrong (standard) cams...

Inlet should be 36,65 mm (1,444 inch)
Outlet should be 35,65 mm (1,405 inch)

They were only installed on the GPZ750A1 - A3.

I have read somewhere that the basecircle on these cams is a bit smaller than the standard KZ cams, so this means you have to buy 8 new shims, when you install the GPZ cams...

Post edited by: Paling1, at: 2007/10/17 07:24

I believe the info on the base circle is on the WebCams site (or MegaCycle cams), and I'm not sure that it applies to all the GPz750 cams or just a few. I have had five sets of GPz750A cams and none of them had a reduced base circle.

As far as identifying the GPz750A cams, it's fairly easy, there is no tach drive on the exhaust cam, although the GPz750 Turbo cams have the same specs as the KZ650 cams and don't have a tach drive either, but they are pretty obvious visually (much more rounded lobe profile and shorter lobes).

The MegaCycle cams for the 750 are awful tempting

Colin (reborn650) Cottoncandyninja, and several others on here have GPz750A cams, and no one has mentioned having reduced base circle cams so far, although they might have an advantage after a valve grind.

Post edited by: steell, at: 2007/10/17 08:13

Paling1 wrote:

I have read somewhere that the basecircle on these cams is a bit smaller than the standard KZ cams, so this means you have to buy 8 new shims, when you install the GPZ cams...

Don´t know if these are the cams you´re referring to, don´t even know if they´re GPz cams, but I have a set of cams that´ll drop into a 650 head. The lobes are the same length as stock 650 cams, but the base circle is 1mm smaller than stock cams meaning they have 9 mm lift where the stock 650 cams have 8 mm lift. They also have a significantly fatter profile than the stock cams = more duration. On top of this they have the worm gear for the tach drive.

More info (and pics) can be found here.

Post edited by: OnkelB, at: 2007/10/17 12:50

I think the only cams with a reduced base circle are the 82 GPzs, which as Steel says aren't the wildest.

where would i find the difference of lift and duration for the two different cam sets?
i know the 84 ones are .354 lift and i'm not sure on duration but i think it's 250.
anyone know what the specs are for the 82 set i have?

According to the manual the 82 KZ750R (GPz) has 3 more hp than the KZ750E, and uses the same cams which have 270 degrees duration.
The ZX750A (83-85 GPz750) has 286 degrees duration.

The manual does not list the lift.

I "think" that Kawasaki measured the duration at zero valve lash, but I don't know because they don't specify. So you can't really compare Kawasaki cams against aftermarket cams in any meaningful way.

Post edited by: steell, at: 2007/10/17 19:35

They (Kawasaki) do state their figures at zero lash. Sometimes sites like Megacycle will give the stock cam duration at 0.40" or 0.50" alongside their own cams so that you can make a comparison.