1981 GS750E (GSX750E) Rat Cafe Racer

LKS

Been Around the Block
Well.. I've been drilling some holes and the "corner"-holes on the nuts are a pain to drill. The bolts are OK, I drill them at a 90 degree angle, but the nuts.. I've given up on them. Mostly because I dont have any 2mm drill bits left :/ 3mm drill bits hold well, and I'll use 2,5mm drill bits for the rest of the perpendicular holes (it's a national holiday today in Norway, and I can't get new drillbits). I think the problem is that the bits snag on the hardened surface when you push through on the other side. I've heard that drill bits for drilling circuitboards are cheap and work great for this. Maybe I'll try them later.The bolts for the brake discs will be OK when they are drilled and wired. I'll buy titanium bolts for the brake conversion later.

For the sprocket bolts I've ordered these Pro-bolt pre-drilled aluminum nuts with steel core. They are very popular in MX competition and should hold up well. They also make them in titanium, but these were in store, and I don't want to wait.
lspn10dbk_7 by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
Perseverance has turned frustration into joy once more :) I googled around on how to drill bolts and got some tips on drill-speed and pressure on drillbit. I've read before that small drillbits require high speed, but this guy said to use slow speed, max 1100 rpms. Geared mine to the lowest, wich is 550 rpm. He also said to oil the bit every 30 seconds :0 That told me I was way too impatient! I can now drill the bolts by listening to the sound the drillbit makes. If it makes a kind of crackling sound, the bit is either about to pack full and overheat or about to brake through the hardened surface on the other side. If the first is true, I back the bit out and clean it and reapply oil. If the bit is about to break through I'm very careful with how much pressure I apply. This was a bit tideous, but I didn't breake anymore drillbits. Took me about 1.5 hours to drill all the bolts for the front and rear discs. I also painted the center of the rear brake rotor. Pictures included as usual:

Rear rotor, painted and drilled bolts torqued down, The one odd bolt is the magnetic one. Should have drilled it last, as it made the drillbit magnetic and a pain to clean.
IMG_20200521_222827 by Lars Krogh-Stea, on Flickr

This is how it was before:
IMG_20200520_210733 by Lars Krogh-Stea, on Flickr

This is how the safetywiring looks now. I went with connecting two in pairs instead of three. I watched a youtube clip of an older guy wiring a propeller for a small plane, and tried to copy what he did. He had several very good tips on how to twist the wires to keep them tightly in place.
IMG_20200521_180148 by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
I'm sure you're pretty tired of me posting pictures of safetywire by now, but I recieved the new nuts today. Must have been an older version as they were NOT drilled :( Anyhow, as they do look much nicer than the ones I that are on now, I drilled them myself and put on a couple of nuts to see the results. Pretty satisfied :)
2020-05-25_11-12-34 by Lars Krogh-Stea, on Flickr

I also put together the GSXR fork to get a bether view of how it all fits together, and I must say I'm sceptic as to how I'm supposed to fit a spoked wheel between those calipers? The angle is little off on the picture where I measure. The more correct measurement is about 47mm (1.85inches). As they are radially mounted I could get some 320mm discs but that would only move them 1cm towards the narrower part of the wheel.
2020-05-22_09-15-19 by Lars Krogh-Stea, on Flickr

2020-05-22_09-15-57 by Lars Krogh-Stea, on Flickr

2020-05-22_09-15-43 by Lars Krogh-Stea, on Flickr

I checked the Cognitomoto wheel and they have laced it with all spokes on the inside. Mine are the usual inside/outside. If that's how it's done I'll need another set of spokes to get all of them in the correct angle, and then I might as well get a wider front rim/tire. then it starts to get expensive.. If I have to do the front wheel all over again, I will have to wait for the winter to do the fork swap :/
cognitomotowheel by Lars Krogh-Stea, on Flickr
 

50gary

Under the Limelight
You have the brake calipers mounted upside down. The witness is the bleeder nipples should be at the top of the caliper to vent the air.
Flip the calipers and right side up to gain more clearance. Can happen to anyone.
Cheers, 50gary
 
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cb250nproject

If you can make it better do so
I have done the same thing on my bike, rim goes on first then the calipers, then when you remove the rim, calipers off first then rim comes out.
IMG_9416.JPG
it should work


Sent from my iPhone using DO THE TON
 

pidjones

Over 1,000 Posts
GL1800s require calipers (or at least one) off to get the rim off. But yes, make sure calipers mount with bleeder at top, or you are doomed forever to spongy brakes.
 

50gary

Under the Limelight
That's a given, removing calipers before wheel.
But the point in question is that the wrong way mounted calipers creates the problem situation I.E. that the wheel (hub) won't fit because of the offset of the calipers when mounted incorrectly.
Cheers, 50gary
 

LKS

Been Around the Block
That's a given, removing calipers before wheel.
But the point in question is that the wrong way mounted calipers creates the problem situation I.E. that the wheel (hub) won't fit because of the offset of the calipers when mounted incorrectly.
Cheers, 50gary

I, can't see how this comes into play.. When I flip the calipers, they also need to swap left/right between fork-legs, or else the brake pads will end up on the outside of the caliper mounts. Or am I not understanding you correctly? I will mount both the calipers and the triples correctly later, but I can't see that it will make any difference with regards to clearing the spokes.
 
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LKS

Been Around the Block
I have done the same thing on my bike, rim goes on first then the calipers, then when you remove the rim, calipers off first then rim comes out. View attachment 226098 it should work


Sent from my iPhone using DO THE TON

That is an awesome setup, but I've set my mind on trying to make it work with the original hub/wheel. The Cognitomoto wheel is laced with all the spokes threaded from the outside of the hub. You can se it in this video;
This means that I would have to source other spokes, because the original spokes won't do. First off, the outer spokes would have the wrong angle. Secondly, a double set of inner spokes wouldn't work either, bacause, as you can see in the video, half the spokes need a longer neck at the bend to get behind the other spokes. I don't know if I explained that clearly enough, but it' in the video. The Cognito hub is by far the best solution of course, but I've set my mind on the challenge. But.. as I've said earlier; if I have to relace the wheel and figure out the dimensions for the new spokes, I will probably go the CognitoMoto route myself :)
 

LKS

Been Around the Block
I have mounted the hoodlatches for the "quick-release" seat:

IMG_20200530_210232 by Lars Krogh-Stea, on Flickr

Cut the bolts to length, drilled and tapped them. Then I mounted them on flat piece of steel:
IMG_20200530_210210 by Lars Krogh-Stea, on Flickr

IMG_20200530_210059 by Lars Krogh-Stea, on Flickr

I will cut this plate to size and screw it on to the frame of the rear seat:
IMG_20200530_210104 by Lars Krogh-Stea, on Flickr

This is how it looks underneath the rear fender when the seat is locked in place:
IMG_20200530_205935 by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
Did a test run with a GoPro mounted to the swingarm to check how the shocks work after rebuild. These are vintage Koni 7610 with the preload set to the lowest out of 3 (twist sleeve) and rebound set to 2 out of 4 (twist dial on top). They're filled with 5W fork oil. The short videoclip is from passing over a speed bump at moderate speed. You can also spot one of the hood-locks. The seat stays well in place.

 

LKS

Been Around the Block
As the Covid situation drags out, and I'm busy working overtime at the hospital, I made the decision to buy the Cognitomoto front wheel. This wheel costs more than I paid for the whole bike, but there's no way I'm gonna have time to do all the nessesary modifications to my old front front wheel. This will be my xmas gift to myself, a reward for working all the long hours:

photo_2020-11-27_23-48-38 by Lars Krogh-Stea, on Flickr
 
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LKS

Been Around the Block
I've done some preparations ahead of the fork swap. Put the before and after measurements in to a free calculator i found online:


The graphic presentation looks like this:
forkswap_2 by Lars Krogh-Stea, on Flickr

As you can see, the fork is a bit shorter (2") and the wheels aren't as tall. The rake changes from 28 to 26,4° and the trail changes from 4,3" to 5". Also, the wheelbase is shortened by 2", part because of going away from leading axle and part from the framedrop resulting from the shorter fork. The triple offset i almost identical, but the offset is still cut in half because the leading axle adds another 1,2" (30mm). I've kept the rim diameter equal to stock, but I've changed tyres to 150/70-18 on the rear (4.25" rim, ran this tyre this summer and I'm loving it) and 120/70-19 in the front (3.5" Cognito-moto wheel being built as we speak). Ran with 100/90 on spoked 79' GS-wheel this summer. I think I've avoided spooky turn-in problems by not swapping in a 17" front wheel while lengthening the trail, but would love if anyone could look over the numbers and tell me if I'm running into any surprises :)
The measurements are not exact, but pretty close unless I've done any measuring or conversion errors (I'm taking measurements in mm).

forkswap_1 by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
Well, it isn't christmas without a gift from me (and sometimes my wife) to my motorcycle :) This year it was the nicest gift since the brake master/clutch. Most of the stuff I get for my bike is either pretty cheap to buy, or they're cheap because I make them myself. And to start, the bike itself was as cheap as they come. The most expensive parts so far are the m-unit and the Accossato brake master and clutch levers. Second is the Motogadget Mini and the rear wheel. The Cognito Moto front wheel that I bought this year probably costs the same as all of the others added together. It certainly cost more than the bike itself.

On the other hand, insurance for the GS750 is next to nothing and compared to the insurance on the Kawasaki Zx7-R I drove when I got my license, the Cognito Moto wheel costs about two years worth of insurance. Better to give the money to myself ;) Just realised that what you have been witnessing in the last few sentences is me justifying to myself the process of bying a ridiculously expensive part for my bike :eek:

Anyway..I've been looking for cheaper ways to convert to GSXR front fork with spoked wheel. There are other companies that make conversion hubs for motorcycles and most are even more expensive than Cognito Moto. Most of the time they are also far from being as complete a package. I thought of milling one myself, but there's not much room for errors and as T8erbug (thegsresources) said, aluminum blocks that size are so expensive that it doesn't make sense when you factor in errors and do-overs. Another option was a Harley front wheel or buying just the hub from CM and sourcing the other parts myself. I know Harley wheel is only 1mm or so narrower. Used Harley parts aren't as cheap in Norway as they are in the US. Adding to this is the price of special spokes. The cost of other options vary wildly, but the CM spokes are really high quality and looks great.

The last option was to make new front axle to convert my original front wheel. This would be a good option if I didn't want to use a radial fork. The radially mounted calipers sits closer together than older brake setups. On the original GS fork there's already little room between the calipers (depending on wheel size, some use GS1000 calipers with the tapered back to get the wheel to fit).

Long story short; I could probably, with a substantial amount of work/time spent making contacts/sourcing parts/money spent on parts that I didn't need/money spent on materials for adapters and so on, make a front conversion wheel for something between 50 to 75% of the price of the CM wheel.

The way the situation is now, that time is better used working overtime at my regular job and using the extra money to buy a preassembled CM wheel. It's certainly a satisfying feeling to have made something like this (I've alredy made the rear wheel from parts :) ). On the other hand, you can't take away the feeling when you unpack such an awesome product as the CM wheel.

Conclusion/TLDR: You can not go wrong with buying the Cognito Moto front wheel. The quality is awesome and if you factor in your own hourly rate, I don't think you can make it cheaper (unless you are a professional).
 

LKS

Been Around the Block
And here's a couple of pictures of the wheel/GSXR rotors and the custom Cognito Moto steering stops I bought with bonus points from buying the wheel. The unboxing experience really is premium and the wheel comes with soft cloth "showercaps" on both sides for protection. The bolts and steerings stop come in separate small cloth bags that are tied to the spokes so it wont get lost ine the styrofoam pellets.

Cognito Moto Gsxr Wheel by Lars Krogh-Stea, on Flickr

Cognito Moto Gsxr Wheel by Lars Krogh-Stea, on Flickr

Cognito Moto Gsxr Wheel by Lars Krogh-Stea, on Flickr

Cognito Moto Gsxr Wheel by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
Made a new drawing of the front wiring. The current setup is a bit messy, and with the new fork/headlight, I just as well redo it all. Too many wires together makes the loom stiff, and I'm grouping the wires by maximum five.I'm also running the wires inside the clip-ons this time, including the front brake-switch.

Wiring front by Lars Krogh-Stea, on Flickr
 

LKS

Been Around the Block
Got a couple of hours in the shed today. First task was cleaning the calipers from the new forks. I'm going to paint them black, so they will have to be really clean. All pistons move ok, and the pads are not too worn. Maybe I'll change pads anyway, now that they are out. It feels better to know what I kind of brakes I have. I can keep the others as emergency backups. As usual, a before/after photo:

Top triple by Lars Krogh-Stea, on Flickr
 

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