Another Z650...

[Bevelhead]

I couldn't work out why the bike was only running on 3 cylinders, however the green F2 carbs were very clean, so I replaced the carbs on the bike with the F2 carbs and without much hope, hit the starter.... and the engine sprang to life on all 4 cylinders for the first time! I still have no idea what's the problem with the no1 carb off the bike, but now I know for sure the fault lies with the carb and not anything else.

Sadly the F2 carbs can't stay on the bike as they are needed for the F2 in a couple of weeks time.

[Bevelhead]

While there a few small items that need to be done, such as rechroming the kickstart and brake lever (to be done next winter), and of course the original carb problem, the bike is now finished..

[KWACKERZ1]

Looks good, nice job

[Bevelhead]

Another day and another Z650, but not mine this time, but one whose build I shall be following. My friend is doing the work for a customer, who has owned the bike for more than thirty years, and so is very attached to it.



It has some old cool parts fitted, such as the CMA wheels, Davida swing arm, and a Gpz750 engine. All these parts will be going, as its being fitted with a big bore Gpz750 turbo engine, with a bigger turbo, already built, along with modern wheels, brakes and suspension.

As of yesterday the bike has ben stripped, and the frame will be put on a frame jig to make sure all is well, before being braced.

[Bevelhead]

More work done on the Z650 turbo ...

ZRX1200 swingarm, billet yokes to fit ZXR750 forks and wheels, and mounts added for one off rear sets. The frame has now gone off to be powder coated at Triple S in Bingley.

[Bevelhead]

With the frame back from powder coating, and new stainless engine bolts made, time to fit the turbo engine into the frame, or rather fit the frame over the engine. Soon became clear that the turbo engine mounts were different from that of a Z650, the upper front mount being missing from the turbo motor, while spacers will be required elsewhere.

[Garry.L]

A standard 750 Turbo runs nearly double the power of a Stock Z650, add on those mods as well and it should be a seriously quick bike.

[Bevelhead]

Just heard that the turbo engine will have to come out of the frame and be stripped right down, as a serious problem has been found in the rebuilt engine. The engine was rebuilt at great expense, by some workshop 'down South' who I'm told are no longer trading.

The Hyvo primary chain is so loose that when the transmission is turned, it just slides over the crank. Its clearly far too long. Must be from a different model, perhaps someone fitted a chain from the 750 twin??

With such an obvious mistake, everything will need to come apart and double checked.

[Garry.L]

Don't know if it's any help but plenty of good info on here. https://www.750turbo.com/forum/index.php

And.. https://www.750turbo.com/manuals/750%20 ... 0Parts.pdf

[Bevelhead]

Don't know if it's any help but plenty of good info on here. https://www.750turbo.com/forum/index.php

And.. https://www.750turbo.com/manuals/750%20 ... 0Parts.pdf

Oh the turbo isn't my bike thankfully, will be interesting to see if there is anything else wrong with the engine when its taken apart. How any workshop could fit a primary chain that is so obviously wrong I don't know.

[Bevelhead]

With the correct length chain fitted, the engine is now going back together..

[Bevelhead]

While over Xmas, I bought a 78 650 frame, complete with all important V5, which is the start of a new project for me. I only bought a frame as everything else, apart from the bodywork will be changed. The goal is to get the bike down to 400lbs dry, with over 80 bhp, along with modern suspension and brakes. In the pic below can be seen the first mod, a ZRX1100 swing arm, which in turn needed work to repair some crash damage.








The front end I wanted to use, soon hit a snag, as the stem of the R6 yoke was too short. Therefore, a Z650 stem will be liberated and used with the new bottom yoke. Since the R6 uses clip ons, I bought a top yoke from an FZ6 Fazer of the same year. Sadly the FZ6 has different dimensions from the R6, even though they both use 43mm forks.

The wheels will also be from an R6, as I had a good pair left over from a previous project. They are impressively light, as are their discs and calipers, along with tyres, these parts alone are 30lbs lighter than the standard Z650 parts.

The R6 rear spindle is 28mm, while the ZRX 1100 is 20mm, so will need to make suitable adaptor spacers..

[Bevelhead]

I bought the GPz 750 engine I've had my eye on, the engine last ran 24 years ago, but it turned over ok by hand. It wasn't long before it was striped down.



The engine came apart ok, had a problem with the oil filter bolt, as it was rounded off. Had to chisel it off in the end. While the top fin on the barrel was found to be broken. This was repaired by welding in a shaped piece of alloy, not by me, but sometimes its not what you know, but who you know...






With the engine taken apart, its cases have been sent off to be ceramically coated, while the frame was sent off to be powder coated. But not before the frame was welded, to add a few tabs etc.

Meanwhile the clutch basket has been modified to remove the looseness caused by its cush rubbers getting old. This was done by grinding off the rivets holding on the back plate, then inserting steel sleeves around the rubbers which take up up any slack and prevent movement of the rubbers. Finally the back plate was welded back into place. New rubbers are now available, but at £108 a set, this option is cheaper.



With the frame back from powder coating, made a start fitting the rear plastic mudguard, along with a stainless plate to replace the original chrome guard, which of course I didn't have, and didn't want as they are so heavy.

[Bevelhead]

For this project, its having wheels, brakes and forks from a 2004 Yamaha R6, which is the year before the model switched to USD forks. I choose these donor parts as I like the 5 spoke wheel design, which are also impressively light, while the 43mm forks and 4 pot blue spot calipers are some of the best fitted to a Japanese production bike. I've also used these wheels before, and knew they'd work with the ZRX swing arm.

However, when the rear wheel was fitted into the swing arm, it was clear something was very wrong.. it didn't fit!

With the wheel hard against the left side of the arm, it was still miles out from being central in the arm. Very odd, took awhile to work out what was going on, as the ZRX1100 is the same width as the ZRX1200, which I'd used successfully before.

Eventually found that the rear wheel wasn't in fact from an R6, it was from a later model, an FZ8, though it was sold on Ebay as from an R6. Despite looking identical, they are not, the hub is much wider, even the cush drive is different.

I've since bought a cheap R6 rear wheel, but its silver, not the gold of the original, so now I have a mismatched front and rear wheel. Will probably have them both powder coated. A pity as the front wheel is in perfect condition.

To fit the wider back end, which has a 5.5 x 17 wheel, the pillion mounts on the frame have to be removed, not a problem as they were rotten inside in any case.



FZ8 wheel wont fit the ZRX swing arm..

[Bevelhead]

Back to the Turbo bike, the stanchions of the ZXR750 forks had been rechromed at some point in the past.. badly. At 43.15mm they were too thick to work correctly. They were taken to Dynasurf in Sandbach, where the chrome was removed and reapplied correctly, this was much cheaper than buying new stanchions. With that done the forks could be rebuilt and fitted to the bike.