[bladeracer]

Originally Posted by LoopyLee

I'm looking for parts for my old Z and hate to see bikes where there is nothing wrong with them, being stripped for parts.

Is it the same engine as my '84 GT750 (KZ750P)?
It's the two-valve GPZ750R engine but with a shaft drive.
Can you put a 750 topend on the 650?
It's my next resto project after I get the XS250/400 finished.

[LoopyLee]

Originally Posted by bladeracer

Is it the same engine as my '84 GT750 (KZ750P)?
It's the two-valve GPZ750R engine but with a shaft drive.
Can you put a 750 topend on the 650?
It's my next resto project after I get the XS250/400 finished.

No.. Chain drive and don't know about the 750 top end..

I was checking through the engine parts when we cleared all the cr@p out of the garage yesterday and I realised one of the pistons is damaged , so am on the hunt for a replacement one.. The good news is that I don't need new piston rings as it looks like the ones on the pistons are brand new which I'm very glad of as they are £47 a piston...

[bladeracer]

Originally Posted by LoopyLee

No.. Chain drive and don't know about the 750 top end..

I was checking through the engine parts when we cleared all the cr@p out of the garage yesterday and I realised one of the pistons is damaged , so am on the hunt for a replacement one.. The good news is that I don't need new piston rings as it looks like the ones on the pistons are brand new which I'm very glad of as they are £47 a piston...

I don't know yet if the crankcases are the same between chain and shaft drive but I would actually prefer to get rid of the immensely heavy shaft drive and swap to chain.
I was just thinking the 750 would be more common than the 650 is all.
How much mileage is on your engine with those pistons?
Why did the engine come apart if it's already been rebuilt recently?
Mine is my brother in law's bike. He lifted the top to put rings in it but caught a ring when he put the barrels back on and scored a bore. It's not that bad so I could probably just replace that piston and rings and put it back together but I want to push it out to at least 900cc (73mm bores) and rebuild the whole thing so he has a new bike.

[LoopyLee]

Originally Posted by bladeracer

How much mileage is on your engine with those pistons?

I have no idea, but the pistons look fine to both SSB and I, apart from the one which has been damaged. A piece has been broked off the bottom of it so a new one is needed..

Originally Posted by bladeracer

Why did the engine come apart if it's already been rebuilt recently?

The engine was apart when I bought it.. According to the bloke I bought it from, the previous owner had stipped it when it started smoking a bit.. but then had gotten a tad carried away and TOTALLY stripped the bike I bought it as a kind of rolling chassis, and a crate full of parts.. Mind you, I've continued the stripping now so that she can have her frame painted and everything.. Basicaly I'm rebuilding her from the ground up..

The original plan was to restore her back to totally standard, but thats changed now and I will be tweaking a few things as she goes back together.. I want to keep the overall appearance of the Z as I love that look but I'm thinking single shock, a bandit swingarm will fit with a bit of tweaking according to the Kwac owners club, possibly upside down forks to beef up the front and make her a bit more stable plus a few other changes

Originally Posted by bladeracer

Mine is my brother in law's bike. He lifted the top to put rings in it but caught a ring when he put the barrels back on and scored a bore (Thats a bugger Will make sure I'm very careful putting mine back together). It's not that bad so I could probably just replace that piston and rings and put it back together but I want to push it out to at least 900cc (73mm bores) and rebuild the whole thing so he has a new bike.

'New' bike sounds good

[bladeracer]

Originally Posted by LoopyLee

I have no idea, but the pistons look fine to both SSB and I, apart from the one which has been damaged. A piece has been broked off the bottom of it so a new one is needed..
The original plan was to restore her back to totally standard, but thats changed now and I will be tweaking a few things as she goes back together.. I want to keep the overall appearance of the Z as I love that look but I'm thinking single shock, a bandit swingarm will fit with a bit of tweaking according to the Kwac owners club, possibly upside down forks to beef up the front and make her a bit more stable plus a few other changes
'New' bike sounds good

You need to measure the pistons and the ring grooves to know if they're good - looks don't mean a great deal :-)
What year is your Zed?
I wouldn't go with inverts myself as they don't provide any real advantages. Late GSXR600 conventionals are excellent forks but they are very short so might not work. Earlier SRAD 600 forks are probably a bit longer but they aren't quite as good as the later ones. CBR600RR forks might also be an option but I've never measured them. If you're looking at the Bandit swingarm maybe try to get Bandit forks as they're not bad, although they don't have much adjustment. One big advantage with the swingarm and forks is that wheels from the RF900, 750/1100 Katana, GSXR 600/750 SRAD, TL1000, Busa and some others are all the same as the Bandit so they're cheap and readily available without having to make spacers and such. The 6.0" rear wheel may also improve cornering clearance if you can fit it in there.

[LoopyLee]

As I 'accidentally' jacked a thread I thought it best to move things here..... So..............

[LoopyLee]

I just came across this load of information here...

The z650 and z750 motors are basically exactly the same bottom ends. z650's have kick-starters, z750's don't. You can fit a set of z750 pistons and cylinder onto a z650 bottom end, for a cheap conversion to a 750. Heads are interchangeable. Fitting a 650 head onto a 750 bottom end will give you a slight increase in compression as well - always a good thing. z650 and z750 motors can be swapped between 650 and 750 frames.

You can even fit 750 Zephyr bits to the early motors, they use the same bottom-end, lots of castings and just dress the outside up a bit.


You *cannot* fit an early Z900 / Z1000 motor into the z650/z750 frame. You can however fit the later GpZ1100 or Z1000J motors into the smaller frames. The reason is that the early 900s and thou's had the kickstart casting at the rear of the cases, the later 1000's and 1100's don't, and thus can be squeezed into a 650 or 750 frame. Its a tight fit - I just did a Z1000J motor into a 1980 z750 frame for a Period 5 racer I am currently building. Its a really tight fit, but it can be done. You need to take the cams out to fit the head on, then put the cams in and keep going !

Most of the early 650's, 900's and 1000's use 36mm forks. These can be swapped between models pretty freely. z650 or z750 triple clamps will fit into z900 or z1000 frames, and give you much quicker steering due to the reduced offset. I have used z650 triple clamps in the Black Pearl now for 10-12 years ?? can't really remember when they went in.

Brakes - the early 900's used 6-bolt disc rotors, from the 1976 Z900A4, they went to a 4-bolt pattern. z650's also used a 4-bolt pattern, so disc rotors can be swapped freely between all models that use the 4-bolt rotor. All 4-bolt disc rotors are 295mm diameter, so no worries changing between models. The early 6-bolt rotor is the same as a H2750, as is the early-model calipers. Calipers from the 1976 900 can be freely swapped between most 1000's up to 1980. Rear brake drums / hubs can be freely swapped between H2 and early 900's with a drum brake rear. You will need to change some small items, axle spacers etc, but this is pretty easy.

From the Z1000J onwards, different calipers were used - GpZ1100 calipers can be freely swapped with J calipers from 1981 to about 1983.....the parts interchangability started to decline in the early to mid 80s, there are a lot of external cosmetic stuff that can be changed, eg GpZ1100B1 and B2 and Z1000J tanks are the same, but from 1983 onwards, the models became a lot more *specific* to themselves, in a lot of respects. During the 70's, it was another story altogether !

The twin-disc setup can be done on every Z900. They all came with a set of mounting lugs on the lower RH fork leg, and the RH side of the front hub is already drilled. Getting a disc rotor is easy, but getting a RH caliper for an early Z900 will cost you an arm and a leg. Stick a set of Z1000A1 (1977) forks on an early 900 if you want a twin-disc set-up, its way cheaper.

Wire-spoke wheels - these are freely interchangeable between all spoked model Z900's and Z1000's. The spoked front wheel of a Z650 is also exactly the same as the z900 spoke wheel. The 650 rear wheel cannot be interchanged, the rear drum and hub is smaller than the 900/1000.

Stay away from the Z1000ST - shaft drive model. *Nothing* on these models will interchange with anything else, apart from the barrel/head to other Z1000's. Everything else is different, wheels, brakes, forks, everything.

There are a few good Z Owners websites, but none of them have any type of list of parts interchangeability.........good to get knowledge from, and parts.

[Twincam]

Originally Posted by LoopyLee

(it wasn't just me though)

...blame everyone else

[bladeracer]

Very good info Loopy.
I've already got my head filled with info about the one I'm working on now so I'll hit that site up when I start that job :-)
Very cool about the Zephyr engine - I'll have to set up yet another Ebay search to warn me when one comes online.

[LoopyLee]

Originally Posted by Twincam

...blame everyone else

oh poo!!!! You got that before I edited it out of the original post

[Twincam]

Originally Posted by LoopyLee

oh poo!!!! You got that before I edited it out of the original post

Need to be quicker!

Regarding the Changeability - would any of the parts which are on the bikes I menctioned in your previous post fit?

[Twincam]

Originally Posted by LoopyLee

oh poo!!!! You got that before I edited it out of the original post

Need to be quicker!

Regarding the Changeability - would any of the parts which are on the bikes I menctioned in your previous post fit?

(SR/KZ?)