1981 gs750 (gs750e) Retro Racer project

[LarsKroghStea]

I made a housing for the Motogadget Mini. I'll glue this into the triple so I won't have to glue the Mini directly.





3D printing doesn't give a perfect surface. When the CNC-router is finished, I'll probably go back and recreate these parts in aluminum. Meanwhile it's a cheap and easy way to prototype and test parts

[LarsKroghStea]

The front is slowly coming together again. I'm not using Weather Pack connectors here as it's much easier to put the clip-ons together if the connectors fit through the clamps and the connectors will be located up under the tank so waterproofing isn't as important. I think the result looks pretty clean


This is a 6mm hole. I bored it up to 8mm after i took the photo so I could extend the nylon sleeve inside the housing. That makes for two extra layers of abrasion-protection; the nylon woven sleeve and the heat shrink sleeve





The tool is the same one i use for the Wather Packs. People who use a lot of WP connectors will most likely have a more expensive tool that doesn't require one step pr crimp. I have the less expensive one. It takes longer to use, but is more versatile i guess.




And here's the result:

[LarsKroghStea]

The last couple of days I've been testing a few designs for the control-housings. I pretty confident they are in their final iteration now. Today I designed and printed the headlight brackets. They're attached to the fork-legs by stainless exhaustclamps.

[LarsKroghStea]

Started to do the wiring for the controls. I'm drilling a hole in the clip-on tubes for the wires (from inside the controls) and I'm running the wires inside nylon sleeves for protection and looks. I wont bother with Weather Pack connections as the connections will be inside the headlight.
I've removed the screws from the switch-terminals and soldered on wires to make sure they don't vibrate loose. I'm aware of the opinions on soldering from earlier discussions, but my opinion is that a few soldered points aren't any problems.

[LarsKroghStea]

Not much happening.. but I got some stuff in the mail; A HEL brake line for the rear (they were on sale for some models) and an original (I hope, it says "made in Japan" on the sleeve) clutch cable. The clutch is extremely hard to pull, and I don't want to search for other faults before I've eliminated the cable as the source.

[LarsKroghStea]

I measured the trail. Don't know how accurate you can measure it, but I think it's pretty close. I make it out to be 114mm, and I'm pretty sure stock is 107mm. 7mm longer, and I don't think that will be a problem for now. If I don't like it, I'll make new triples with 20mm more offset. That won't be until winter though

[LarsKroghStea]

Rolled the bike out to take some photos. This is definitely the look I'm going for What's left is (afaik); redo wires and cables, brake lines and pads up front, change rear brake reservoir and brakelines, speedosensor at rear disc, make the left footpeg on the lathe, make new support-rod for rear caliper, mount Motogadget Mini and gear-indicator in the triple, make gear lever plus connection rod, make brakcet for license plate and rear brake light, mount front indicators and some other minor stuff.. The list was longer than i thought..

[LarsKroghStea]

Painted the calipers with caliper (spray)paint. Very difficult to get an even surface, and i don't think that paint will take sanding very well. I have an anodizing-kit that I bought some years ago, that I haven't gotten around to try out. I think I'll strip these for paint as a winter project and anodize them black instead. For now, I'll live with the bad finish. I guess this kind of paint is more for protection than looks..


I also gave the "Ducati Monster Aluminium Performance Fender" (I think that's the original name) a couple of coats of aluminum base and BMW sapphire black.



I'll try it on and decide whether I want to keep it black. The finish looks awful without sanding and painted at too low temperature, so I'll throw in a picture of the same paint on the old forks:



The fender is originally mounted like this:


But I've drilled the rivets and will make something like this:

[LarsKroghStea]

About to give the rotors and calipers a fresh coat of paint (the calipers aren't finished yet):

[LarsKroghStea]

So far, I'm using the stock GSX-R triples. They are 30mm offset, about the same as the stock GS triples. That means I'm getting about 2cm less offset than stock, as the GS-fork is leading axle. I don't think I will make it a priority right away, but if anyone has information on stock triples from another bike that fixes this problem I can start looking for a set. I've browsed through the tables in other forums, and didn't find anything, so if there really is an available solution (except expensive aftermarket parts) it would be a hidden gem.

If the steering is too sluggish, and/or if the front tire gets too close to the exhaust under fork compression, I think I will put adjustable triples on my to-do list for the winter.
I hope the cnc-router is working by then and I have a lot of large pieces of glued oak (kitchen countertops) that I get for free from a local store. They are awesome for doing cheap cnc prototyping.


Here's a prototype I made for the GS-fork that I didn't mill in aluminum as I decided to go for the USD fork instead.






Does anyone have either drawings (CAD) or pictures of suitable adjustable upper and lower triples?

[LarsKroghStea]

Moved the headlight lower and liked the look. Also did a quick photoshop of the fork when compressed (like the Photoshop pro I am.. ). It seems the fender will touch the lower clamp just before the tyre hits the exhaust. I need to set compression and preload so this doesn't happen, but I don't think it'll be a problem. I'll also hook up a GoPro for the first few rides to see how the fork behaves.

[LarsKroghStea]

Finally! I think I'm happy with the looks. I've been so afraid that something would be wrong with the front setup I've chosen. Either that the wheel would be too big, there would be too little ground clearance or that the wheel would be too close to the exhaust. The front is still incomplete, as it's missing fender, the headlight sits about 6-7cm too high, the brake rotors and brake lines are not there and so on. But I think the geometry is fine The gap between tire and exhaust is about 7cm. I think max travel for these forks are 12cm, but that's under really hard load. I'll drop the forks 12cm and measure the clearances.


Also, I always pictured the fork legs painted black, but now I think I might keep them anodized gold? What do you guys think?














I'll take some better pictures with the seat on soon

[LarsKroghStea]

I think those of you that have followed my build noticed early on that I didn't have much mechanical experience. It's mostly trial and error, and lots of research in advance. I keep at it because I really enjoy the process. I think I'm getting better at it and when enough time and effort is applied, nice things appear

Today I got a reminder that I'm still a newbie at many things. I read online that if you put the stem in the freezer, the bearing should "slide on without much effort". Can't say it did. I couldn't press it on by hand anyway. Adding to that, after a couple of minutes in room temperature frost appeared on the stem because of humid air. I don't want to trap all that moisture behind the bearing, so I'll wait for it to dry. Lesson learned.. Maybe this works for stem/bearing combos with less size difference. I have access to a press at my dads house, but it's an hour away. I want to see the fork on today, so I think I'll just use the old bearing and a tube and hammer it down. Here's picture of the frosted stem, straight from 20 celcius below zero (-4F)

[LarsKroghStea]

The instructions for the All Balls conversion say to measure the old and the new lower bearing, and shim the difference if they are more than one mm apart.
Here's the old one:


And here's the new. No need for spacers:

[LarsKroghStea]

Went on to remove the old fork and bearings today. PO had replaced the old bearings with tapered bearings and the lower bearing (the part that sits in the frame) was a real headscratcher.. the angle is such that a screwdriver will not catch the edge. I tried to make an ad-hoc tool:



Didn't work so well..:




Then I tried this:



Small cut with a hacksaw.



Pushed the tube up through the frame, took a punch and hammer, and bent all the tabs outwards. Went full sircle two/three times with light force. Gave the tube a few blows with a hammer and the bearing dropped to the floor. No scratches in the frame. Much easier I think than heating the frame with a torch (and burning the paint), welding the bearing (shrinking by heat), grinding it with a Dremel or other tips I found on the web.