Time to rebuild my old GPz

[GPZ592]

So, the engine rebuild was started - but quickly suspended as a final inspection of parts before assembly revealed the starter clutch to be worn more than I first thought Rather than just renew the springs and rollers, I've ordered the complete starter clutch assembly and starter gear and it's on it's way from Kawasaki Europe ! Whilst waiting for the parts to arrive, I did a couple of smaller jobs to keep the project moving along.

First job was the seat. I recovered it back in the 80's when the original cover split. The replacement is still perfectly usable (but not standard), but had come unstuck from the base. A few hours spent with a can of evo-stick and some clamps and it's fit to use again.

Seat 2.jpg (90.59 KiB) Viewed 125773 times

Seat 1.jpg (105.54 KiB) Viewed 125773 times

Next , I resurrected the old screen which was dull and a bit scratched. Again, not original, but a period replacement and perfectly usable. First, I used a very fine abrasive pad to remove the scratches. This leaves a very dull finish, then a polish using rubbing compound clears the dullness and restores the shine and finally a quick wax over to finish. Once fitted to the fairing it looked so good - I couldn't resist temporarily fitting it to the bike

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Fairing 2.jpg (116.72 KiB) Viewed 125773 times

Seeing the fairing on for the first time has really given me a boost. Sometimes during a rebuild you think the end will never come, but seeing the first bit of "Firecracker Red" back on the bike really made my day !

Hopefully, the engine parts will arrive soon and I can make more progress !

[GPZ592]

I finally managed to get some much needed garage time this weekend and started the engine build Surprisingly, it all went pretty smoothly and good prgress has been made - long may it continue

[dave spencer]

Nice to see it coming together!

[GPZ592]

As seems to be the case with this rebuild, it's been two steps back to take one step forward

Having got the cases built up, I turned my attention to the assembling the head and that's where my problems started ! I'd had the valve seats re-cut and the valves re-faced, as they both showed signs of pitting. So, after gently lapping the valves in, I did a dry build of the head with the cams in to get an idea of shim sizes required before installing the head onto the engine. However, when I had the correct valve clearances, the shims used were all only 1 or 2 sizes above the minimum shim size available (2.00mm) and that left no room for adjustment in the future

So out came all the valves and I had the tips ground by 0.2mm and once re-installed and checked, the shim sizes used are now about 2.30-2.40 with correct clearances. This won't be a high milage bike, so that hopefully should leave enough adjustment to see both me and the bike out

1 valve lapped - 7 to go !

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Head assembled (for the second time !)

[r3sc]

That’s looking really good! Keep us up to speed with the progress!

[GPZ592]

Just a quick update. I've had to put the engine build to one side for various reasons, but still trying to make progress on other bits & pieces.

Next job to tackle was the carburettors. These aren't the original carbs, but off a GPX600. They're larger 32mm CV Keihins as opposed to the 27mm CV TK originals. It's a known upgrade for the GPz550 which works well with the big bore kit (615cc) and later cams with a bit more duration - both of which I am fitting to mine.

I invested in a small 3l ultrasonic cleaner and proceeded to split the entire carb rack to its individual components as I can only fit 1 carb in the cleaner at a time. The carbs weren't too dirty externally and Initially, I didn't think anything was happening, but after a 20 minute soak, I could see a change in the colour of the carb casings and various other components. Indeed - after cleaning all 4 carbs, the cleaning solution had turned a very muddy brown A quick rinse and a blow out with the airline and they're ready for the next stage - masking off the carbs and spraying them black as per the originals.

Cleaning Tank

Definitely cleaner (right), although the photo does not show it clearly

Yuk !

[Philippe]

Hi GPZ592

that's the way to do it.
Take them apart completely and clean them one by one!
When spraying them black, don't forget to tape off all the openings and mount the float bowl, that way you prevent paint to get inside!
Use a strong two component paint because the fuel we're using today takes the paint off before you realise it!
GrtZ
Philippe

[GPZ592]

Hi Phillipe,

I was going to use VHT engine case paint and then cure it in the oven. Other people seem to have used this type of paint with good results.

Mark.

[Philippe]

Hi Mark

that's a good option! Just make sure ALL the plastic and rubber parts are out before curing the painted carbs in the oven!
GrtZ
Philippe

[GPZ592]

that's a good option! Just make sure ALL the plastic and rubber parts are out before curing the painted carbs in the oven!

Thanks for the reminder

[GPZ592]

Once again there's been a step forward followed by a step back, which seems to be a theme for this rebuild

Progress has been on the carbs, which have been sprayed with VHT black and were then left to air dry for a week, before being "cured" in the gas BBQ (this circumvented the use of the oven in the kitchen and incurring the wrath of the wife ) They've turned out OK and are just awaiting rebuild.

Carb bodies sprayed

In the BBQ !

Next was supposed to be a giant leap forward for the project, but it didn't turn out as planned

So, with the help of a mate, it was time to get the barrels on the engine and then drop the part assembled engine into the frame. It all started well enough, we dropped the barrels onto the engine (checking the cam chain was out of the way) and the centre 2 pistons went in without too much of a problem. The outer 2 however, proved to be a right pain ! Everytime we managed to get the rings on one side started, the other side would pop out. No matter how we tried it we couldn't seem to get the barrels over the outer 2 pistons. "it feels as if the barrel is not lowering straight" says my mate " is anything fouling it ?" So we checked and couldn't see anything, until I looked down the cam chain tunnel and there it was - the rear cam tensioner blade had jammed itself into the opening on the rear of the barrels for the cam tensioner assembly You couldn't have done it if you has tried ! It all made sense - the more we pushed the barrels down, the further it went into the opening in the casting, eventually stopping the barrels going any lower. If that wasn't bad enough, where the blade was now jammed in, we couldn't lift the barrels off to release it ! Eventually, we managed to raise the barrels enough to get at the 2 cap head screws retaining the rear cam blade to the c/cases and undo them, so we could lift the barrels and cam blade off the engine............................................ At that point, I decided to call it a day and go and sit down in a darkened room to recover Later inspection thankfully revealed no damage to the pistons/rings or barrels, but the cam blade had some nicks in it t, so I've ordered a replacement for when we try again.

Ah well, onwards and upwards !

Mark.

Cam Blade 1

Cam Blade 2

[Skid Mark]

I've done the very same thing Mark, you weren't the first and wont be the last. Great work BTW.

P

[GPZ592]

I've done the very same thing Mark, you weren't the first and wont be the last. Great work BTW.

Glad I'm not alone You feel such an idiot when something like that happens........................

[GPZ592]

It's been a little while since I've updated progress on the GPz. After the debacle with the cam chain tensioner blade, I had to spend some time fettling one of my other bikes before a trip to the Manx GP, so it wasn't all bad Once I got back, it was time to turn my attention back to the GPz.

Carrying on from my last update, it was take 2 on getting the barrels onto the pistons. Thankfully, all went well this time and with the help of my mate and and some home made piston ring clamps we got the barrels on OK (and there was much rejoicing !). Flushed with that success, we then lifted the bottom half of the engine into the frame and suddenly it began to look a bit like a bike again. The cylinder head went on OK quickly followed by the cams. Now comes the bit I loath - shimming the valves As the GPz is shim under bucket, any adjustment involves taking the cams out again and removing the buckets to replace the shims. Even though I've done the procedure many times before, it still makes me nervous every time I re-tighten the cam cap bolts - It's the irrational fear that I'll strip one..................

I did do a dry build on the bench to get the initial shim values somewhere near, but checking the clearances now everything is installed, they're all just outside tolerance You only want to do it once, so the key is to measure everything twice and then double check, just to be sure

Mark.

Barrels on and into the frame

Ready for the head (yes, I did add the oilway pins and O rings !

Cylinder head on

And finally the cams are in !

[Philippe]

Hi GPZ952

great progress!
As far as the fear of stripping a cam cap bolt is concerned: you're not alone! I have the same feeling every time.
Continue the good work.
GrtZ
Philippe