1981 GS750E (GSX750E) Rat Cafe Racer

LKS

Member
Spendt most of the day gardening and working on my home gym.. both me and my sons miss going to the gym in these Corona-times. Did get the time to buy the hood-locks though. Here are som e pictures of how i envision the fastening device for the rear seat. I'm putting some rubber between the seat and the frame to prevent vibration and to put the hood-lock under tension so it won't rattle. I will also have to test which position is best.. I'll either drill and tap the square tubing or drill two metal pieces to clamp over the square tubing. We'll see.

Setefeste by Lars Krogh-Stea, on Flickr

Setefeste by Lars Krogh-Stea, on Flickr
 

LKS

Member
I guess it's when you start riding that the errors you've done come back to bite you.. I thought the ride was extremely harsh, and when I went out yesterday to bounce the shocks.. this happened.


I thought the hash ride was because of the thick oil and the cold weather, but I could just as well ridden with steel rods for shocks :eek:
I feared the worst..


that I had to buy new ones.

I took them apart to see what was wrong. Apparently the vibrations from running with thick cold oil rattled loose the end screw (1m) from the rod (3). Don't mind the arrows. That made the whole valve sink to the bottom and the spring pulled the rod through part 1c, wich is what it bottoms out on when I bounce the bike. 1c rests on 2a and that tube rests on the shim 2c on the bottom of the shock body. The only part with som visible damage was on 2c on one of the shocks. Some markings and it's bendt, but very little. I'm reusing it as it doesn't have much valving function.

Dempere by Lars Krogh-Stea, on Flickr

The internals, washed and end screw torqued to spec with a dab of blue locktite. Filled up the shock with new SAE 5 oil.

Dempere by Lars Krogh-Stea, on Flickr

The cool thing about having built a home gym, is that I've apparently also built a pretty safe and easy way to compress springs ;)

Dempere by Lars Krogh-Stea, on Flickr

Dempere by Lars Krogh-Stea, on Flickr
 
Last edited:

cb250nproject

If you can make it better do so
I can't believe I missed this somehow, I thought I was following this after watching you build those mean rearsets, shes coming along nicely, its always after a few test rides where the gremlins come out, all part of the journey cant wait to see her in full effect
 

LKS

Member
The shocks are back in working order :) Next up is safetywiring of the rotors and rear sprocket. Some of the safety tabs are in bad shape and one of the screws in the front disc came loose. Before i do anymore testdriving I'll have to go over the whole bike and refit the screws with with correct torque and loctite per manual. There's been too much jumping back and forth over several years and I have clearly forgot where i've test-fitted parts and where I've done them up correctly. Safety first (from now on)!
 

CarbsAndCylinders

Careful With That Axe Eugene
I guess it's when you start riding that the errors you've done come back to bite you.. I thought the ride was extremely harsh, and when I went out yesterday to bounce the shocks.. this happened.


I thought the hash ride was because of the thick oil and the cold weather, but I could just as well ridden with steel rods for shocks :eek:
I feared the worst..


that I had to buy new ones.

I took them apart to see what was wrong. Apparently the vibrations from running with thick cold oil rattled loose the end screw (1m) from the rod (3). Don't mind the arrows. That made the whole valve sink to the bottom and the spring pulled the rod through part 1c, wich is what it bottoms out on when I bounce the bike. 1c rests on 2a and that tube rests on the shim 2c on the bottom of the shock body. The only part with som visible damage was on 2c on one of the shocks. Some markings and it's bendt, but very little. I'm reusing it as it doesn't have much valving function.

Dempere by Lars Krogh-Stea, on Flickr

The internals, washed and end screw torqued to spec with a dab of blue locktite. Filled up the shock with new SAE 5 oil.

Dempere by Lars Krogh-Stea, on Flickr

The cool thing about having built a home gym, is that I've apparently also built a pretty safe and easy way to compress springs ;)

Dempere by Lars Krogh-Stea, on Flickr

Dempere by Lars Krogh-Stea, on Flickr
Cool idea to use the weights for something :)
 

LKS

Member
While I was there, I also got some parts.
New BTR UK made brakelines:
IMG_20200506_220338 by Lars Krogh-Stea, on Flickr

New Domino throttle control with teflon cablesleeves. These are for push/pull applications, but I'll only use one wire and keep the other for spare. The controls come with three different ratio cams (stock photo, didn't want to unpack them):
domino-xm2-quick-throttle-control by Lars Krogh-Stea, on Flickr

I've also bought Ruffian roadracing grips:
IMG_20200506_220349 by Lars Krogh-Stea, on Flickr

I did bring my 2005 GSX-R 750 USD forks, complete with radial mounted calipers and disks, although I probably won't use them just yet. I've had a plan for a while, to use the Cognitomoto comversion hub, but as this is a 1000$ solution I'm researching the possibility to use offset rotors on the original GS spoked wheel that I run now. I know ducato rotors from the bikes that came with Øhlins forks are available in both 10 and 15mm offset versions. This is a thought that came to me just the other day, and I'm not shure if it's even a possibility. Here's a picture of the forks:
IMG_20200506_220458 by Lars Krogh-Stea, on Flickr
 

LKS

Member
Another option would of course be to try to source some narrower triples. Let me know if you have som info on this.
 

LKS

Member
Well.. I've done som research one the fork-swap and ordered a set of new rotors (discs). I'm not going to make the swap until everything else is in order, but it doesn't hurt to start collecting parts early. I have the original GSXR-discs, and I'll sell those as i'm not using them anymore. These are the rotors I bought, they are from a 1993-95 Honda CBR900RR.

s-l1600 (1) by Lars Krogh-Stea, on Flickr

They have the same PCD (78mm) as the original disks. That way I know I can drill and tap for them. The discs are offset 17.2mm. The original discs are offset 22mm, wich is a lot. I was hoping they were flatter, but I think I have aluminum slabs that are thick enough to make the spacers. Spacers would need to be about 1/2 inch thick, good news is that the lip that the disc rests on is protruding about 12-13 mm from the mating surface on the hub. that will create a solid base for the spacers. I'll countersink holes in the spacers for the original screws. Then I'll drill between the screws and tap the holes to fit the original honda screws (or, as I don't have the original bolts, I'll maybe buy cross drilled titanuim bolts) I have those for the Suzuki discs, but I'll sell those too. Next photo shuws the original hub. Should be easy to make spacers for this one:

2020-05-08_12-07-10 by Lars Krogh-Stea, on Flickr

I've also measured the original front axle and it is about four millimeters longer than the GSXRs. It is of course thinner, but I'll make new spacers and bushings in the lathe.

I'll paint the GSXR forks all black. I dont like gold forks on cafe racers like this:
cognito-fork-swap-5 by Lars Krogh-Stea, on Flickr

I want them to be like this:
honda-cb900-origin8or-10 by Lars Krogh-Stea, on Flickr

Of course there are also GSXR1000 forks with black inner tubes as well. They are awesome, but much harder to come by. I like the chrome inner tubes almost as much ;)
 

LKS

Member
I'm not exactly proud to show you the images I'm about to post.. Normally I'm very concerned about safety. When I reassembled my last bike, I followed the manual to the letter and I had no worries with running it at 140mph+. Remember I hastily bolted the bike together to ride it home from my father? When I was almost home, some noise from the front wheel made me stop and check. I couldn't see anything and assumed it was the bearing. Drove it home and parked it. Became aware of the shocks, fixed them and today I was going to fix the front wheel. And the speedometer, as it stopped working shortly before I arrived at home.

It seems the two problems are related. The rotorbolts that became loose have grinded the speedogear to bits :/

IMG_20200517_112631 by Lars Krogh-Stea, on Flickr

IMG_20200517_112644 by Lars Krogh-Stea, on Flickr

IMG_20200517_115207 by Lars Krogh-Stea, on Flickr

Pretty sure this speedogear is not going to work again..
As the new plan is to use the original front wheel with the Gixxer forks, the speedo analog/digital converter is now a forgotten, but fun, sidetrack. The new plan is to use a magnetic bolt on the rear brake rotor.
 

LKS

Member
On the positive side I've been practicing my safety wiring skills. I don't quite know why I started drilling the corners of the bolts. They are pretty small, and hard to drill in a way that looks nice. Adding to that it looks better when drilled straight through. I redrilled the middle bolt and will drill that way on the remaining bolts. I also had to put a shim under the bolts because of the threadless part, that's why they're not positioned perfectly. I don't have the bolts for the new rotors and wil probably buy predrilled bolts for them.

2020-05-17_08-01-03 by Lars Krogh-Stea, on Flickr
 

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