Z650 build, mix of Zephyr, GPZ and B3 650.

[Crofty]

Been on with this since September, so ignore the what I did today bits, i might of done it weeks ago.
Have been collecting parts for a while to build a spare/new motor for me 650. Just got the casings and covers back from vapour blasting and giving them a good clean to be sure no media left in the oilways and threads.
Its going to be Z650 crankcases and gearbox, GPZ750A1 crank, rods, barrels, pistons and cams and a Zephyr750 head ( I like the look of the Zephyr head as it is like the 900 with rounded cam cover and has more fins for better cooling.



Note extra space at end of cams, much more metal in the Zeph heads.


Will need to round the corners of the barrels with a file to match Zephyr head.



Came to start putting the cases together and made a faux pas in the choice of cases. I had early 650 ones which did not have the slots to locate the cam chain tensioner blades. Doh.
Anyway I was going to do a std 650 rebuild on an early engine, so these are going under the table and have just purchased a reconditioned head from Dave Bones.
So,I found a cheap F2 engine, prefer these cases to later 750 as they have the correct spacing of engine mounts to fit straight in any 650 frame and added benefit of no need to bore the throats to accept 750 liners and had them vapour blasted.
Before taking them to be cleaned, I bought new shells and checked with Plastiguage and they are all OK. This time I used the stampings on the crank and crankcases, all good. Previously I have had the internal bores on the cases measured and the crank micrometered up.
I also scored a new old stock primary drive chain at less than half price, new cam chain and oil seal set.
When rebuilding the 650 /750 motor I like to treat it as 4 stages.
First stage. Get cases together, replacing any items critical to good running, bearings and chains, plus crank 'o' rings, gearbox parts etc
Second stage. Insert fully rebuilt starter clutch, new ZR7 oil pump then sump on replacing the 'o' rings and oil filter as well.
Third stage. Barrels and head on, new pistons and rings in this engine, rebuilt head also.
Fourth stage. Bang all side components on, restored clutch basket, new clutch plates, ignition, alternator rotor, output shaft cover.

While I was looking for the primary chain, I had Plastiguaged the crank and rods and assembled using the existing bearings as they were unmarked and within tolerance, only putting new mains in on this one



Picture shows one of the ports that let the oil pump feed the transmission shaft bearings with oil.
Need to make sure these are not clogged with blasting media before assembling.

[Crofty]

I spent a fair bit of time cleaning out all the oil ways, which were not too bad. Trial fit the transmission and fit the selectors. Had to order a alternator side oil seal for the crank as the GPZ750 A2 cranks have a larger diameter taper (NOTE, the genuine Kawasaki crank seals are identical to the ones supplied in the aftermarket kits which include all the other seals, kickstart, crank, final drive shaft output clutch push rod etc), will be needing a rotor to go on there as well.
I also dug out some Loctite capable of applying to the transmission shaft bearing outers to keep them in place, a few of the engines for 650/750 I have pulled apart show signs of having turned in the crankcase halves.



Shifting forks and drum.


Transmission.


New mains shells.


Before that I had spent some time at the weekend getting the cases together. When doing this I apply an engine build lubricant (Lubriplate) to the bearing shells, I brush stag well seal around the outer edge of the crank oil seals (1 at each end of crank)some hmp grease on the lips of the seal, I applied some bearing locker to the gearbox large roller bearings as these two are not pinned for rotation. Finally I put the bonding sealer around the faces of the cases to be joined.

Main bolts in and torque, then all the smaller bolts that hold the cases. Its always done fairly quickly as the case sealer wants to dry quickly and I leave that as the last one to be put on.

Next was the starter clutch.

With the starter clutch on this engine, it needs to be right as no kick start, so I bought the whole assembly, new clutch with pins, springs and rollers already in and a new gear. Not cheap at about ?130 the pair, but at least I shouldn't have any bother from it.

The bearings on the ends of the starter clutch shaft felt a bit notchy, so replaced with genuine Jap Koyo bearings from a bearing supplier, less than half the price MaKaw want and theirs are Koyo too

Next months pay packet should cover an oil pump (ZR7 type), relief valve and some seals and a filter, then sump can go on.





Trans chain and new starter clutch assy.


Improvised gear puller made from 3 old bolts, spare gear and a socket with extension, had to move gear out of way to allow bearing retainer to slide in there. This is held in place by three countersunk screws, two pass right through and into the oil pump. I was too keen and drove the gear on forgetting that the plate goes behind, Should mention that there is a bolt screwed into the end of the shaft to allow the socket to wind it out and the 19mm socket pushes the spare gear away from the shaft pulling the splined gear with it.

[Crofty]

Well I ordered the oil pump and found they were on back order, so have sent the barrels and pistons to SEP engineering for re-bore and ring gaps. I need to add sump 'o' rings (3 small and 1 large) and paper gasket to the list of parts as well as a new oil filter to complete the crankcase internals.

I will be needing 4 GPZ /Zephyr exhaust valves, but these are expensive, might use Moriwaki man in Japan who sourced me the pistons cheap, if I cant find any closer ones.

Oil pump arrived Thursday am and got around to fitting it tonight.
Took picture to show differences,



Fitted

[Crofty]

Bottom end on, new o rings, filter and gasket went on tonight. Preparing clutch assy. I will need to soak the new plates and buy a new centre lock nut and gasket. Also thinking of getting the APE clutch pusher. Only ?18gb from Z1 enterprises.

Block should be done so phoning SEP tomorrow to get that back.


O rings in place and oil pump filled with oil to help start up.


Sump with Stag Wellseal brushed onto mating surface.


Filter ready to install.


Note the clutch hub bush has a small hole, otherwise identical to the output shaft bush behind the final drive sprocket.


Rebuilt basket I have had lying around for a while now.

[garyd]

A little off topic question but you seem to know your stuff regardiing the Z650/750 engines.

What's the biggest cc you know of that's been made out of one of the 750 engines?

Just a pub dicession I had months ago and didn't seem to get resolved.

Cheers

P.S. nice work on the engine

[ADRIAN H]

Wiseco 810cc kit for z750 barrells.

[garyd]

Yeah 810 is the one we all know about...wondered if anyone elase has bored/stroked for a different size?

[ADRIAN H]

Yeah 810 is the one we all know about...wondered if anyone elase has bored/stroked for a different size?

JE Pistons / MTC Pistons do not make anything for Z750.
Wiseco only make a 810 kit for Z750, which is the only kit easily available.

http://kzzone.com/pistons.html

[Crofty]

M Posh do an 820 kit, I know a guy in Canada who has an MTC 831 in his link in bkts (http://z650.proboards.com/thread/802/street-sleeper), they stopped the mtc kits around 1990.
The actual answer to Garys question based on a quick net search is 880cc, see footnote.


Below is an exert of a tuning article
Stage 3: More cc with the Wiseco K810 bigbore kit. Wiseco states in its catalogue the engine displace with 810cc. In fact it is 807.7cc, if we calculate with the official Kawasaki numbers (stroke 54mm). Wiseco claims a stroke of 54.14 mm, that´s why the displacement is said to be 809.8 ccm. The Wiseco pistons have a 3mm bigger diameter, are forged pistons and raise the compression up to 10.25:1. Arithmetically the compression ratio should be a little bit higher, around 10.4:1 with standard combustion chamber. The kit contains all necessary pieces and a new head gasket. New liners are not required. There are other bigbore kits, which are available in Japan. JB Power offers pistons manufactured by Cosworth with 68.5 mm (796cc) and a compression ratio of 11:1, whereas the kit contains all needed parts and a head gasket. M-Posh goes a step further and can supply a kit with 69.5 mm and a cr of 11.5:1, that makes 820cc. Because these kits are barely known in Europe and Wiseco can ship without problems I only mention them. Bigbore kits by other manufacturers (MTC, Arias etc.) fit as well, as long as they are made for the old aircooled Z650/750 engines.
Dynoed with Wiseco 810cc pistons, GPZ cams, Mikuni RS 36mm flatslides and a Remus 4-1 with a racing can. Result: 85 HP at the wheel, significantly higher performance at higher engine speed. Noticeable more torque around the whole rev range.
With the increase of around 10% (738cc → 808cc) and the higher cr the engine produces more power around the whole rev range. A negative point is, that the vibrations increase. Not later than at this point we will need stronger clutch springs, which shortens the life of the clutch cable. An option is the installation of the clutch from the turbo. This has one more pair of plates and clutch slipping is no longer a problem.

Had a quick look on 750 turbo site and saw 880 is a possibility
http://www.750turbo.com/forum/viewtopic ... e&start=15

TBH I think you start running into difficultys at anything over 810 in regard to liners moving, overheating and keeping oil inside as any oversize liners make the base gasket narrow.

[GIMPieZ650]

There was an 880 kit for the turbo gpz750 turbo engine which used a stepped liner in a standard barrel and crank cases, so you could in theory go that big but the most common of the shelf kit is the wiseco k810

[Crofty]

The APE clutch pusher turned up, so spent this morning putting it in. I was unsure to use 650, GPZ750 or EBC springs. So after some consulting of 3 different manuals and doing some measuring of springs, I have used my GPZ ones.



Contents of kit.


Bearing in place with engine build lube and just the outer washer to go on..


Gasket to go on later after whatever I decide to do to the finish on the cases.

[750steve]

Yeah 810 is the one we all know about...wondered if anyone elase has bored/stroked for a different size?

831cc is as big as i know of

880cc turbo kits leaked like hell apparently

[Crofty]

The barrels arrived, so spent a bit of time after work putting the pistons onto the rods and getting the barrels on.
Interestingly I found the Kawasaki original 650 ring compressor will allow the rings to be squished in enough to allow the barrels to be slid onto the pistons easily. I had plenty of oil and assembly grease around the rings and liner throats and they slid on without any bother. I have used a few large nuts on 4 of the cylinder head studs to hold the barrel down till I install the head, which is now on the priority list to get finished.

[Crofty]

Not had chance to do much to this one for a while with christmas and work. I sent the head away a few weeks ago to have the valve guides done. Came back last week and finally got chance yesterday to fit new viton seals and install the new valves. Then I bench shimmed the clearances for the valves. Just need a couple of oilway jets which superceeded to a different shape and I can put the head on and dial the cams in.






Head now on, having cam wheels machined and slotted, before I can install the cams.

[Crofty]

Cam wheel machining will be next week, so have started to polish various bits up. Going to do cases black with polished clutch, points, generator, sprocket cover polished and the cam cover black with the end bits polished.
I also rounded the gpz fins off to blend in with the Zephyr head.