Z650 into 810 project

[Crofty]

I picked up a cheap late model(F2) Z650 motor last year with a 750 top end (pity it wasn't a GPZ one).
Since then I have been cleaning it up and sourcing bits and pieces to make a sleeper.
So far I have cleaned and painted the cases, dug out my best crank, had the rods balanced and shot peened, picked up a set of hardly used 810 pistons, set of seals, new camchain, rebuilt the infamous starter clutch, gearbox all OK, cam chain guides and tensioners all OK.
I'm having a set of 650 barrels fitted with 750 liners, for the full sleeper look.
I am not far off putting the bottom end together, just need to buy some kawabond and a primary chain off Z Power.
Then its just a case of saving up to get the head work done.


The Wiseco pistons against the std 650 ones.


Shot peened and balanced rods.


The cases close to final assembly.

Next year I aim to find a basket case chassis or a ratty std 650 to put it in.

[Crofty]

Managed to get a bit more done today. Thoroughly cleaned up the crank and blew out with air at the local bike shop. Put in all the new shell bearings with lots of oil, after checking them all with Plastigage. Popped the new primary and cam chains onto the crank and slotted the gearbox in. The mating surfaces are degreased and I just need to get a low reading torque wrench and some high temp grease (for the end seals).

[pertonpc]

Nice work Jim,
keep the photos coming. Long live the 650s
What mods will you do to the head

[Crofty]

Pete, Going to leave that to Ray at Debbens, its the one big thing I would love to be able to do, but without the tools and the training, I think I will leave it to them. The only thing I ever ported was my 400 Yam with a bit of knife-edging and lifting the exhaust port a millimetre.
Got a std 650 head and a gpz 750 head (it might of been played around with in the past and not sure if it will be suitable), the 750 head will accept the mods more easily having already got larger intake valves and slightly worked at the factory inlet tracts.
Ray says they can fit new guides, valves and springs, do a seat job, a skim, cc the combustion chambers and open the ports on either. It will cost more to do the 650 head, to get it to being close to the 750 one. Putting gpz750 cams in and have a set of 26mm vm's. 24 is std. Could always go up to CR29mm carbs, but pricy, but have heard and read they give a big increase in performance at the loss of a bit of lower end tractability.


gives a good account of what can be done to the 650 to give a good power increase and thats only out to 720cc.

[pertonpc]

Cheers Jim
Looks like a cracking article Jim, will have a good read later. Am thinking of doing the shims on my 650 head this winter - and may take the opportunity to check the valve stem seals and seats are good. Will post some pics for your advice if I do it.
from Mark

[knut]

looking good crofty,i,ll be keeping a close eye on this as i,ve got a z750 project planned for later this year,

[Pigford]

Great stuff lad

[GPRD]

Crofty, where abouts in York are you? I'm in Holgate.
Would like to be able to pick your brains and use some of your contacts for the next project I start.
Cheers

[Crofty]

GPRD, I am just off Bishopthorpe Road, if you fancy meeting up thats not a problem. I have just rebuilt the bottom end and will be posting some pictures soon. Crofty

[Crofty]

Made good progress over the last couple of days. dropped the crank, chains, gearbox etc into the upper crankcase half, bolted it together, slipped starter clutch assembly in, installed APE cylinder head studs, sump pan on, new filter in. Goes through all the gears OK
Basically the bottom end is together, just needs secondary shaft bearing nut and clutch nut torquing up, but need the special clutch holder and alternator rotor holder to stop everything spinning.
Also went over to a mates and mig weld tacked the nuts on my rebuilt clutch basket.
Waiting for machine shop to finish the barrels and then send off head to Ray Debben.

RH view of the motor, outer cases are just on to see what it will look like.

[Rich]

Engine looking good - although I would ditch the wellies.........

[GPRD]

Crofty, I'll be in touch, should be getting my next project soon, another Z650!
Cheers

[Crofty]

No probs GPRD, speak soon, Jim

New clutch tool turned up this morning and have now tightened up clutch centre nut and secondary shaft end nut. Bottom end nearly done, just need heavy duty clutch springs and the needle roller type release.

Tightening the centre nut.


Job done.


Finishing off the secondary shaft nut.

[Crofty]

Thinking ahead, I realised I will need to be able to access the cam wheel mounting bolts to dial the cams in. The chain needs to be under tension to do this accurately and as this is the hyvo type chain the tensioner sits inside the cover itself.
So using an old US spec cam cover I chopped most of it away, leaving the tensioner part only.

[Pigford]

Al (Zorded) made a tool for taking up Hy-Vo tension - but its for GPz1100 type motors

In reality I found it surprisingly made bog all difference to timing the cams