1981 gs750 (gs750e) Retro Racer project

[Diirk]

I blazed through your thread and that thing looks insane. Really bad ass.
Overall I'm a little tired of seeing bikes getting chopped up for "caferacer/scrambler conversions" or whatever... but this thing is none of that.
Very well executed. Absolutely brilliant work my friend :encouragement:

 

[LarsKroghStea]

I blazed through your thread and that thing looks insane. Really bad ass.
Overall I'm a little tired of seeing bikes getting chopped up for "caferacer/scrambler conversions" or whatever... but this thing is none of that.
Very well executed. Absolutely brilliant work my friend :encouragement:

Thank you very much for the kind words

 

[LarsKroghStea]

So, the fendermounts came the other day. They were thicker than I expected, and I also expected them to have a shim welded to the bottom so they would hide the bolts.
A little like this:
https://blackdiamond-motorcycles.ch...nt-bmw-r80-r100-cafe-racer-bobber-conversion/

The ones i recived looked like this:

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They were also way too long, but that's of course better than the alternative;



I've not descided on wether I'll shorten and bend them, grind them flat and drill/tap and put them on the underside, or bend them and weld them together as a loop.

I'm leaning towards this look:
https://www.caferacerwebshop.com/en/front-fender-scrambler-with-brackets.html

 

[LarsKroghStea]

The new footbrackets have arrived, and for some reason the mounting points are different from the ones I have. The rear holes doesn't allign, and is positioned 4-5mm forward and forward/up on the other one.



And the metal tabs on the frame must be flush to frame on '82 and protruding about 15mm on my '81:



There is plenty of metal that can be removed on the inside of the bracket, but it might be necessary to also alter the metal tabs on the frame.. This turned out to be more work than I expected, and I'll save this job for later. I don't regret buying the brackets though, as they are a very nice starting point for making new, nice looking brackets

 

[slayer61]

That's the way I HAVE to look at it sometimes... I didn't buy a part. I bought a pattern!

 

[LarsKroghStea]

That's the way I HAVE to look at it sometimes... I didn't buy a part. I bought a pattern!

That's a clever way to look at it

 

[LarsKroghStea]

Guess who's back..

As this b​uildthreads 10th anniversary is coming up this december, it's about time I finish documenting the latest mods. And finishing the bike.

This is a list of things to come:

• Finishing the rearsets - I've driven the bike with the original gearlever and no functioning rear brake.
• Upgrading the rear shocks - The Konis are a bit soft, and they have been relocated to my Dnepr-project.
• Keyless ignition via phone proximity (bluetooth)
• Yamaha R1 front caliper swap - to better match the master cylinder bore.
• Updated rear lights - integrated with blinkers.
• New headlight mounts with Motogadget mo.blaze tens.
• LED "cockpit" lights in the top triple.
• Front fender - need to weld new mounts. Have bought welder.
• Maybe rear hugger/fender.
• Relocate licence plate to swingarm
• Mounting pickup for speedsensor.
• Making mount for Motogadget Mini.

And probably a couple of other things that I've forgotten about.
I've been dissapointet a few times myself, when build-threads suddenly die before isssues I'm following are resolved, and I will do my best to answer the questions I left hanging.

 

[LarsKroghStea]

First; gearlever:



This involved just cutting the original gear lever, turning it 90 degrees upward, drilling and tapping it and using a turnbuckle to make it adjustable.
I've pressed in rubber O-rings to stop it from rattling.

The rearset location on this side is fine without the footpeg mount, so I'm skipping it. This makes it neccesary to fit a spacer on the swing arm bolt. If I can't find one that fits, I will make it on the lathe.

 

[LarsKroghStea]

Rear brakes:

On this side it was neccesary to use the footpeg mounts. I cut and shaped them to fit better, and I also had to remove the tab on the frame, as it interfered.with the mount.

 

[LarsKroghStea]

The new rear lights (and you can see the rear brakes in the background).:



They are 3 in 1 lights, with turn signals, low power red rear lights and high power red brake lights. The are extremely bright too.



I drilled and tapped the frame and screwed them directly to it.

 

[LarsKroghStea]

I soldered the LEDs to a protoboard with 510Ohm resistors in series (as the LEDs are 3V max /20 mAh). The black ground wire is looped here for testing, but the final version has ground wires. One in common for turn signal/high beam, and one to ground the oil light. I bought quality LEDs, but they can break so i made the oil pressure light (skull) reduntant and with separate resistors.

 

[LarsKroghStea]

The switches are reconfigured:

Left is:

1. Lights. Short press - blink high beam, longer press - switch high/low, even longer - turn off.
2. Turn Left. Short press - blink 3x, longer press - blink continously. Stop with short press.
3. Turn Right. Press both 2 and 3 for hazard lights

Right is:

1. Start. Read below.
2. Horn (Can also be used to configure M-unit, but I use my phone for that)
3. Motogadget Mini operation (configuring and switching between infoscreens)

The keyless start is configured like this:

• Approach the bike with bluetooth turned on and mo.ride app (service) running on your phone. The phone will connect to the bike and a (turn)-light signal will tell you it's connected.
• Push start x1 to turn on bike. Motogadget Mini display shows startup animation.
• Use starter button to start your engine. Light turns on automatically. Light can be turned on an off by holding light button
• Press Start x2 to stop engine.
• Press Start 2x again to turn off ignition

In the video I'm testing the system without starter relay connected.

The display can be configured for both horizontal and vertical use.

 

[LarsKroghStea]

When doing th R1 monoblock-swap, there is a choice between switching from 298 to 310mm rotors, switching to 320mm rotors and using 5mm spacers or milling 6mm from the calipers at the contact point (red markings on image).



I don't want bigger rotors, as I think they look out of place on these bikes, so I'm choosing the last option. I will post the result later this week

 

[Rich82GS750TZ]

Thanks for hanging in there and updating the thread. Looks great.

 

[LarsKroghStea]

So, after double-crimping a lot of connectors on both the gear indicator and the other indocators, they finally work:

Forgot to film the gear-indicator, but here's a link to an old clip:

 

[LarsKroghStea]

Milled off 6mm on the R1-calipers today.
I've been postponing this job for a while, as I was afraid to screw it up. After some testing i found a way to mount the calipers. Two impact sockets of equal hights, a bolt through one of them and a bolt through the center. Doesn't look professionl at all, but it worked.

I didn't want to put too much pressure on the setup, and did three passes with 2mm removed for each pass.

The surface looks rough, but is actually completely smooth. I can say I'm very relieved
This looks exactly like other pictures I've seen online.

 

[LarsKroghStea]

Mounted the calipers today, and the rotors now seem to line up well with the frictionmaterial on the pads.

Here is an overexposed image i took to better see if everyting lines up as it should. The pads will sit a little bit deeper when the retaining spring plates are back on:

These are the new pads:

 

[steve murdoch]

Nice work, Lars.
When i swapped my Honda over to spokes i acquired an array of washers and brake rotors and calipers to help line things up.
Also got lucky when i discovered that EBC made three different thicknesses of brake pads for the calipers i was using.

 

[slayer61]

Amazing. Very well done Sir.

 

[LarsKroghStea]

Thank you guys

Today I went over all the nuts and bolts at the front, and torqued them according to specs. The steering stem nuts were a real challenge. They should be torqued to 45 and 80 Nm, and both mye C-spanner just slipped and rounded off the nut. I dont have the original tool, which is a socket that fits over the stem and on to the slots in the nut. In the end, this was the solution

Getting the master cylinder to work with conventional bleeding seemed impossible. It was finally resolved by reverse bleeding like in this video: