'87 Kawasaki GPX750R Restoration

[DreadHead]

I recently bought a Kawasaki GPX 750R as a winter poject.

Here is how it is at the moment

https://imageshack.us/a/img821/4591/dscf2693jf.jpg



It has been dry stored in a garage for about 5 years, the previous owner got it at around 19000 miles and has owned it for about 12 years, it is now just on 23k, he last had it on the road about 5 years back

The tank was stored drained of fuel, with just enough being put in to run it every month or so. The inside of the tank looks fairly clean but has the odd 5p sized spot of muck in, so I will be cleaning it at some point.

It's got a new battery, starts from cold on the button but is a little lumpy at idle so I'm thinking the carbs need looking at, although this has been done too recently according to the seller. Once warmed up it's a lot better, but still slightly lumpy.

Electrics and lights work ok too, apart from the temperature gauge which doesn't register anything, so I need to check that out.

Looks like it may need the fork seals doing. It needs a pair of tyres and a chain and sprocket set.

Bodywork is a rather tatty, so I decided to take all the fairings off and have a closer look.

https://imageshack.us/a/img19/1947/dscf2696y.jpg

https://imageshack.us/a/img411/8531/dscf2695.jpg

https://imageshack.us/a/img211/7788/dscf2694q.jpg

Looks like something decided to make the bike its home at some point.

https://imageshack.us/a/img715/4263/dscf2697.jpg

Despite the previous owners assurance that its been recently serviced, I'm going to give it a full service.

Brakes were seized on, so I'll need to check out the calipers too.

Plan is to get it roadworthy for when I get my full licence, and then do a rolling restoration.
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CBT √ Passed, Theory √ Passed, Mod 1 √ Passed, Mod 2 √ Passed
Riding - '87 Kawasaki GPX750R (Rolling Restoration) and '06 YBR125.
Want - Triumph Speed Four or Street Triple

[DreadHead]

Small update!

Done an OAP service on the bike this week, and have a few jobs for the weekend - replace chain and sprockets (DID VX Chain, JR Sprockets, courtesy of wemoto) plus generally tart/tidy up for the MOT

I've cleaned the tank out and the bike runs even better considering the time its been stood.

I'll be ordering a full set of pads as they all seem pretty past it, due to age more than anything (Rears fell apart when i took the caliper off)

I'm currently scouring the 'net for ideas on tyres, I presume it's good practice to match profiles/compounds front and rear. With this in mind I can only find two manufacturers that do matching tyres in the sizes I need, which are...

Front 110/90/16 V
Rear 140/70/18 V

The options are either:-

Avon AM26 Front / Avon AM41 Rear

Metzeler Lasertec Front / Metzeler ME880 Marathon Rear

Does anyone have any experience or reccomendations on these tyres?

Cheers in advance!
____________________
CBT √ Passed, Theory √ Passed, Mod 1 √ Passed, Mod 2 √ Passed
Riding - '87 Kawasaki GPX750R (Rolling Restoration) and '06 YBR125.
Want - Triumph Speed Four or Street Triple

[Kickstart]

Hi

Given how they had a reputation for being a bit nervous at the best of times, probably best to stick with a matching pair.

However think the Marathon is a touring tyre.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[DreadHead]

Realised the tyres I priced up were actually all fronts!

The only two brands that do the sizes I need in a matching pair are either:-

Avon Roadrider AM26

or

Bridgestone Battlax BT45


Price wise they're about the same
____________________
CBT √ Passed, Theory √ Passed, Mod 1 √ Passed, Mod 2 √ Passed
Riding - '87 Kawasaki GPX750R (Rolling Restoration) and '06 YBR125.
Want - Triumph Speed Four or Street Triple

[DreadHead]

Got some Bridgestones on the way, after the results of the poll elsewhere.

In preparation for the tyres coming I put the new chain and sprockets on, after cleaning through the centuries of muck, grime and grease. I then started stripping the brakes.

When I first got the bike you could barely push it, moved okay under it's own power but if you needed to go backwards you were gonna get a workout!

After a quick check it was clear that the calipers had seized, so I've got some seal kits on the way. I spent most of yesterday coaxing the pistons out of the calipers by repeatedly pressurising and bleeding the calipers until each piston was just about out (I'd forgotten how much I hate Brake Fluid, 'orrible stuff and gets everywhere!)

Looks like the brakes were stripped and rebuilt some time ago as there was evidence of copaslip in a couple of the pistons. A couple have slight marks on, I think this from someone removing them with mole grips or similar. The pistons need a good clean, so are sat soaking in duck oil until the seal kits arrive.

Can I clean up the pistons with wire wool/very fine emery cloth to remove the marks? The marks are not deep, or sharp. One has a small burr, which I think I can remove without making it worse. If not I may have to replace one or two pistons, but would rather not as I think they're about £30 a pop.

I will obviously replace them if I think the braking will be compromised!
____________________
CBT √ Passed, Theory √ Passed, Mod 1 √ Passed, Mod 2 √ Passed
Riding - '87 Kawasaki GPX750R (Rolling Restoration) and '06 YBR125.
Want - Triumph Speed Four or Street Triple

[DreadHead]

Another update, unfortunately no pics as my camera is playing up.

Got the bridgestones fitted on Saturday, so when I got them back I fitted the wheels, adjusted and aligned the chain and rear wheel.

Then I started on the calipers which were all seized. A couple of the pistons needed cleaning up, as they had some marks and a small amount of corrosion. I cleaned them up using a combination of wire wool, and for the stubborn bits some wet and dry with a couple of drops of engine oil to help reduce and scoring.

The calipers had quite a bit of old fluid that had crystalised under the old seals. I'd left the calipers soaking in brake fluid to help dissolve the old crap, which seemed to work ok. I cleaned the calipers, greased and fitted the seals and reassembled the calipers.

The calipers took a little longer than expected most, so I left fitting them until sunday.

Sunday morning, bright and early (Well, about half ten) I fitted the calipers and new pads, then I started to bleed them hoping to be done by early afternoon. Rear caliper went easy as pie, bled up nicely, working a treat.

The fronts however, were a different story. They fitted easily enough, bleeding them however was a pain in the proverbial.

No matter how much I pumped and bled I just couldn't get any pressure, all the air was out of the system, but no pressure. After much swearing and muttering at the bike I decided to have a ponder and a pot of tea. I realised that the calipers must be sticking, and thinking back to when I rebuilt the calipers I thought that I may have pushed the pistons back in too far. I took the calipers of again to check, and sure enough the pistons hadn't budged at all.

Remembering a thread I'd read on freeing seized calipers with compressed air I thought I was gonna have to take the calipers to work to fix it, which hacked me off as I wanted to get it done.

Further musings and I came up with the idea of using my tyre compressor for the car

So, without any further mucking about I refitted the calipers, found a piece of tube that fitted into the end of the pump and over the bleed nipple on the caliper. I opened the bleed nipple and switched on the pump, I pressurised each side to about 70psi.

Pulled the lever and the brakes were rock hard

I then bled the air out, which took a while unsurprisingly. I checked the calipers were moving freely and not stuck.

I then took the bike for a little test run to test the brakes and get a general 'feel' for the bike, seeing as I've never really ridden it.

Bike runs well, engine sounds really sweet and the brakes were great.

I need to check the front forks as it seemed to tip in to the left easier than to the right, the chap I bought it off said he thought a seal may have been leaking. I've not checked the forks as yet, I'm going to replace the fluid anyway and go from there.

I didn't see any evidence of leaking, either before or after my little test ride (On private land of course )

Then I just need to put all the bodywork back on and take it for an MOT
____________________
CBT √ Passed, Theory √ Passed, Mod 1 √ Passed, Mod 2 √ Passed
Riding - '87 Kawasaki GPX750R (Rolling Restoration) and '06 YBR125.
Want - Triumph Speed Four or Street Triple

[WULFSTAN]

SO what happened did you get it a mot?
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Your backside is better enough for you to run again, if need be – bristle up the courage of the cornered rat, put on a bold front, and to hell with them. Bluff my boy – bluff, shift and lie for the sake of your neck and the honour of Old England