6 speed in a GPZ750

So thanks to some advice im putting a 6 speed out of a KZ550 into my GPZ750 block.

I have a few questions though since i havnt got the transmission yet (any day now) and i am ordering a swath of parts from the dealer for the rebuild...

Will i need a new front sprocket? i think the kz550 had a 530 chain - and i am stuck with this &#*$& 630 tractor chain..

i would give my left nut to change to a 530 chain but couldnt find a sprocket to fit before (we've all been thru this i know). have my options opened up now? what about the rear sprocket? 530 available too?

help! losing that 630 chain would mean so much more performance and handling for me!!!! i was going to go up 1 or 2 teeth on the back before i decided on this mod.. but i would still like to up 2 teeth in the back..

i guess my main question is.. what front sprocket goes with this setup


(look at some pics of me on my GPZ on my website.. wahooo!)

Post edited by: eel, at: 2007/12/31 16:42

You aren't going to like the answer

The KZ550 transmissions that I have seen have the sprocket held on by a clip that bolts to the sprocket, and the GPz750 sprocket is held on by a nut on the shaft.

The problem is that the GPz750 sprocket is offset, and there is no room for the clip and the bolts (no holes either), and the 550 sprocket is not offset (besides being 530).

By the way, it's easy to convert the rear sprocket to 530, bunch of KZ sprockets will fit.

The following possible answers are the best I have come up with

(1)Find someone to make you an offset 530 550 sprocket (with tapped holes for the clip bolts).

(2) I think (after a lot of research) that the GPz750 trans output shaft will work in the 550 trans, so you could install the GPz750 output shaft in the 550 trans and either stay with a 630 chain or get a 530 GPz750 sprocket (probably have to have made, I bought the last two I found over a year ago).


I suggest number two (but be aware I have not done this yet, still waiting on a 550 trans), then take the stock GPz750 sprocket and a 17 or 18 tooth 530 sprocket to a machine shop and tell them you want the center cut out of both and the 530 sprocket outer section welded on the 630 offset center.

The 530 offset GPz750 sprockets I bought were left over from a group buy on the GPz mailing list, I haven't seen any others anywhere. One (18 tooth) is on my Nephew's (GPzInfested) GPz750 motored 79 KZ650 SR, and he hid the the 17 tooth sprocket



Trivia

It's interesting to note that the KZ750 will bolt in the 650 frame and use a regular 650 sprocket. But the GPz750 motor in a 650 frame requires an offset sprocket.

Post edited by: steell, at: 2007/12/31 18:40

wha!!!!!!!

i got to get back and real the old threads.. i thought for sure i read about someone doing it (the only reason i would do it!!!:silly: )

not good.

i will reseatch the 750 output shaft but at first thought i dont think it has enough circlip grooves in it if there is an extra gear in there.

Yep, I have done it, so has Steve Darlington (not sure what year or model his motor is though), and I think others as well. That's where I ran into the 550 sprocket mount problem and started searching for a solution. Just remember, this problem is solely with the 83-85 GPz750 motor, regular 530 sprocket will work when using the six speed in a KZ motor.

As soon as I get hold of another 550 trans I'll let you know for sure if the GPz750 output shaft works in the 550 trans.

Post edited by: steell, at: 2007/12/31 18:53

well by the end of the week i will know myself, but by looking at the parts on www.kawasaki.com they dont look the same from bearing to bearing.

I may just dril and tap the end of the output shaft and use a bolt with washers to hold the sprocket on.

nice..

I don't know about the transmission, but the 630 to 530 thing is way overblown. A 630 is the same width as a 530, just has longer links so by all logic im my head which may be dead wrong, a 530 chain should really be no lighter than a 630. So a guy has a 630 with 90 links, replaces it with a 530 with 100 links, you still end up with the exact same length and width, so why bother? Other than maybe a 530 is more widely available and cheaper possibly.

just for shits and giggles.. i googled this (yes i have nothing to do on new years the wife is working)

www.dansmc.com/rearchain.htm

check the charts at the bottom of the page and compare the same 530 to 630 chain and you see the pound/foot weights are different..

and frankly Ron, im just tired of people comparing my bike to a farm implement, so thats ANOTHER reason.
:woohoo:

I have a KZ750 motor that's going to get a six speed whenever I get another one, but I have GPz motors that I can pull apart to see if the output shaft works. At this point it would merely be to confirm my guess, but GPzInfested may put one in his GPz750 motor after the weather warms up. That's if he doesn't spend all his free time riding his GPz759 Turbo

I'm curious why you aren't going to 520 chain/sprockets . Availability ? Does Sprocket Specialst's do any ?

Here you go Ron The DID website.

530 is a little over 1 pound lighter per 100 links, and I don't think the extra links in a 530 chain of the same length as a 630 chain are going to make that much difference.

Sprocket Specialist told me they don't make front sprockets, only rear, and JT Sprockets told me there was no one in the US manufacturing steel front sprockets anymore, apparently they are all made in China now

Post edited by: steell, at: 2007/12/31 21:41

steell wrote:

530 is a little over 1 pound lighter per 100 links, and I don't think the extra links in a 530 chain of the same length as a 630 chain are going to make that much difference.

I too wondered. So loosing a couple of holiday pounds is way easier to do.

And I have serious concerns about people who look at other peoples chains and call them "farm implements".

Maybe a friend change is in order.

guys, 1 pound is alot. especially when its spinning at 500 rpm at either end and trravelling fast in one direction and then has to change directions quickly (loop around a sprocket). there is alot of power lost there. add in the rotating mass that is countering your steering and you'll see that that kind of weight might be important to a racer


happy new year