GS750 Cafe Racer Project

[Druid]

A few weeks ago I bought a 1977 GS750. It's a US spec bike which was recently imported into the UK, and it's not UK registered. The seller said it had been standing for 30 years, it is showing 18k miles.



I intend to make a cafe racer based on this bike. I can remember when these were new models and always liked the look of them. I have thought for years that they would make a good basis for a cafe racer (even before they became popular). Also I have a 1050 Speed Triple in the garage as well, so I already have a sit up and beg naked bike

First job is to strip it down. I'm going to take the engine apart to check its condition, who knows what has happened in there if it really has been standing for 30 years. A couple of hours work and it was looking less like a bike



It's hard work getting the engine out on your own. Once out it's easy enough to dismantle. Well it would be but the barrels were a real bugger to get off and needed some heat and the application of some judicious force. Piston rings are all gummed up and will need replacing but otherwise it's in pretty good nick.





I have access to a bead blaster and an aquablaster at work so the engine cases will get a good cleaning during my dinner breaks Five minutes work turns this



to this

[steve murdoch]

I would love to have access to those machines.
Is the aquablaster just high pressure water or is there a media mixed with it.

[GSXR7ED]

That sandblaster works great! Keep posting pics of your work. Thanks!


Ed

[gr333nyboy]

nice work druid! i'm a sucker for a cafe racer, as you can see.

[Charlie G]

http://www.thegsresources.com/_forum/showthread.php?t=212901

Here is a link to a final thread of a 750 cafe done by one of your countrymen last summer. His build thread seems to be deleted (what a shame?) but it's beauty! Welcome!

cg

[Druid]

I would love to have access to those machines.
Is the aquablaster just high pressure water or is there a media mixed with it.

The aquablaster is high pressure water (about 4-5 bar) with very fine glass granules mixed in. The media is recycled though the machine and loses its abrasive edge with time, fresh media cleans more thoroughly but old media gives a better polish. Either one beats the hell out of cleaning by hand

CharlieG, I've seen that video before, it's some piece of work.

[Druid]

I'm old enough to remember the 70s and have first hand experience of the sometimes buttock clenching handling and braking that was the norm back then. I don't want to experience it again so there are some handling and braking mods in the pipeline. Forks are a skinny 35mm so something less flexible is needed. I acquired a set of GSXR750 slabside yokes which fit the GS headstock perfectly, just need to sort out some steering stops. To go with the yokes I have a set of GSXR1100 forks which are 41mm diameter and have lugs to mount two brake calipers. They are RWU forks so will more or less retain the "period" appearance. The yokes have no handlebar clamps so a pair of Honda CBR400 clipons have been fitted, just because I had them in my spares stash.



The 1100 forks are about the same length as the GS forks, the GSXR750 ones are about 30mm shorter. As I intend to convert the front wheel to 18", if only to increase the tyre choice, I have used the 1100 forks to retain a reasonable ground clearance. I intend to keep the wire wheels and use stainless or alloy rims, depends how much money I have to spare. I'm looking for a nice alloy swingarm too, something like a GS1100, or I believe a Kawasaki ZRX1100/1200 item can be made to fit fairly easily. If anybody has one in the back of their garage let me know

There's also some frame bracing planned around the headstock and swing arm pivot. I'll need to practice my welding first, I'm a bit rusty

[Druid]

Time for an update on this I think.

I've painted the crankcases



and the cylinder head



Reassembled the engine, checked the valves



4 ok, 4 too tight. I managed to swap a couple of shims around and only had to replace two shims.

Next job was to tackle the carbs, which were a bit mucky to say the least



We have a big ultrasonic tank at work, so I dumped the carbs in there for a day. It did a pretty good job of cleaning them



The white deposits are residue from the chemicals, it cleaned off pretty easily. Unfortunately the slide in number 2 carb is stuck fast, It's sitting in a bath of diesel at the moment, hopefully that will penetrate and free it.

Not a huge amount of progress but other stuff has been getting in the way a bit.

[JAG]

Considerably more progress than I've been making

Looking good. You thought of hiring out that ultrasonic tank? I suspect that a lot of UK GSR members would throw work at ya.

[Druid]

Not sure the boss would be too happy about me hiring out his kit There's no problem using it to do personal stuff, but I don't want to take the ****.

Oooh, there's a swear filter

[JAG]

Not sure the boss would be too happy about me hiring out his kit There's no problem using it to do personal stuff, but I don't want to take the ****.

Oooh, there's a swear filter

Ain't that the truth. ****ing **** and all that ****

[Druid]

I suppose I should update this thread.

Carbs are cleaned and rebuilt. The slide in no. 2 was damaged but I found a replacement on ebay for £15 delivered.



The frame has been braced around the steering head and swingarm pivot, then powdercoated



Engine replaced in the frame, or more accurately the frame has been put back on the engine. Lay the engine on its side, wrap the frame tubes in cardboard to protect the paint and carefully lower the frame over the engine. Drop the engine bolts in and lift it back upright





The forks have been stripped, painted and rebuilt with new seals



Forks and yokes replaced. I have obtained a 4 into 1 exhaust which I have just trial fitted. Looks pretty good to me - similar to the Wes Cooley racer, with similar levels of silencing i.e. none.



I have some GSXR Slingshot rearsets which will fit with a simple adapter plate. Going to lose the kickstart though





Front brakes are being upgraded from a single disc to twin discs, using Honda Hornet discs and VFR750 calipers. I have made the adapter plates from 10mm aluminium plate, this is just a trial fit, made them this afternoon.



Even though it's coming together there is still a lot to do. Hoping to get it finished in time to put some miles on it this summer.

[Spiff]

Thats the same rearsets I'm using on my own 750 cafe racer, although mine are mounted further back then where you're planning to mount them.
Good progress!

[Druid]

I'm using the original front footpeg mounting hole. I could use the rear one but it would interfere with the rear pegs. They're still a good 150-200mm further back, and about 30mm higher than the originals. That's probably as much as my old knees and hips can cope with.

[Good Times]

Super nice work.