1980 GS1000 restomod

[Guest]

Hey gang, I'm back at the GS1000 restomod game after a number of years away. Good to be back at the GSR! Hope everyone is well.

My old build thread starting back in 2006 is here, but now that the GSR has a Projects/Rebuilds section, thought I'd start up a new thread to share current progress on this build.

Mods include:

Engine/air/fuel/electrical
Wiseco 1100 cc overbore piston kit
Web Cam .395 lift camshafts
GRC welded clutch basket w/ APE hardened clutch hub nut
Oil pump with uprated oil pump gears for higher flow
Dyna coils/spark plug leads
Mikuni RS flatslide carbs
Pingel fuel tap
1989 GSXR 1100 4-2-1 header modified to bolt up to the GS1000 head
Hindle 4-2-1 full exhaust system
Electrosport stator and R/R

Suspension/brakes/controls
2004 GSXR 1000 front end, resprung to 1.0 kg/mm Racetech springs to account for bike/rider combined weight
Monoshock conversion with 2006 GSXR 1000 swingarm and GSXR 750 rear wheel
520 chain conversion
Goodridge steel braided brake lines
GSXR rearsets

The bike as it sits now after tinkering a bit, with the addition of a Yoshimura slip-on (muffler bracket removed temporarily shown here), Earl's oil cooler and billet oil cooler takeoff, superbike bars, and Koso electronic tach/speedo/oil temperature gauge.

I've changed the rear wheel to a 2006 GSXR 750 for better chain alignment. More on that later...

Tail section is off until I get the bodywork repainted.

In order to improve aesthetics (hunched over stance due to short GSXR 1000 forks) and handling (a bit more twitchy/unstable when leaned over than I'd like so more rake & trail needed), I plan on adding about 20 mm of front ride height via some fork cap extensions for the GSXR forks.

As it so happens, the board on the ground under the front wheel is about 20 mm high so it gives a good preview of the before and after stance.

Before:

After:

Other plans for the cold weather wrenching season include:

• Adding a heavier spring for the rear shock to match the bike & rider's weight better - currently too soft
• Fixing the leaky oil pan
• Getting the chain run perfect. I've mocked up a 2006 GSXR 750 rear wheel in the pics above to help in the effort to get the chain run straight. I was using a 2005 GSXR 750 rear wheel before and had to machine the sprocket carrier and cut down the cush drive rubbers to get the chain in the ballpark of alignment. The 06 750 rear wheel is narrower than the 05 at the hub & sprocket by about 5-6 mm without modification. Once I shim the 5/8" offset front sprocket, I hope that the chain alignment will be perfect.
• Adding a wideband oxygen sensor & gauge (Dynojet Wideband 2) to truly dial in the RS flatslide carburetors
• Paint and bodywork - needs a respray and the dent pulled out of the left side of the tank mad after a 0 MPH tipover. Case covers need to be either resprayed or powdercoated. Currently leaning toward a GS1000S style paintjob but in darker, solid blue on top of the tank & tail.

Paint will be somewhere along these lines:

Stay tuned...

 

[salty_monk]

I see you've added a sprocket cover since you let me ride it up Rose Mtn.... :lol:

 

[Guest]

I see you've added a sprocket cover since you let me ride it up Rose Mtn.... :lol:

Hard to ride a bike with your left toes missing, so I've heard.

 

[salty_monk]

Very true that!

 

[Buffalo Bill]

Very nice work! Have you ever converted a bike to vintage racing spec?

 

[Guest]

Very nice work! Have you ever converted a bike to vintage racing spec?

I haven't. Have you? I need to get out to the AHRMA round at UMC next year and check out all the vintage racebikes.

 

[Buffalo Bill]

Not yet, but my 1990 Katana 750 track bike is eligible for Next Gen Superbike, 1982-1992 bikes.
Considered bikes for Vintage Superbike, light, medium and heavy 1972-1982.
I'm close enough to do 4 AHRMA races in the Midwest.
Thinking about it.

 

[Guest]

Not yet, but my 1990 Katana 750 track bike is eligible for Next Gen Superbike, 1982-1992 bikes.
Considered bikes for Vintage Superbike, light, medium and heavy 1972-1982.
I'm close enough to do 4 AHRMA races in the Midwest.
Thinking about it.

Any pics? Sounds sweet!

 

[Guest]

Hard to ride a bike with your left toes missing, so I've heard.

It is! I've been riding for almost twenty years now with a partial left foot amputation from a stunting accident where the bike came over and the engine case landed on my foot while dragging me down the road. Everything from behind the ball of my foot forward is gone. I have to wear a prosthetic now and it makes things more difficult but most people don't even know I have it because I have learned to walk in a way that conceals the fact I have it. I have limited range of motion because I have to wear a stiff boot and I can't feel what I'm doing because there's nothing there where my toes ought to be. Riding sometimes I need to use my heel to shift up which can be awkward and I get missed shifts, but I'm here to tell you it can be done! lol

Never stop riding. If it wasn't so expensive, when my time is up, I'd get buried sitting on top of my bike.

 

[Guest]

I love this bike btw. I'd like those mods on mine.

 

[Guest]

It is! I've been riding for almost twenty years now with a partial left foot amputation from a stunting accident where the bike came over and the engine case landed on my foot while dragging me down the road. Everything from behind the ball of my foot forward is gone. I have to wear a prosthetic now and it makes things more difficult but most people don't even know I have it because I have learned to walk in a way that conceals the fact I have it. I have limited range of motion because I have to wear a stiff boot and I can't feel what I'm doing because there's nothing there where my toes ought to be. Riding sometimes I need to use my heel to shift up which can be awkward and I get missed shifts, but I'm here to tell you it can be done! lol

Never stop riding. If it wasn't so expensive, when my time is up, I'd get buried sitting on top of my bike.

Wow, impressive that you have been able to keep riding with that injury! Much respect!

 

[salty_monk]

There is a member here in California who shifts a 79 850G with a prosthetic leg. She has a heel & toe shifter fitted & carries a hook to lift the sidestand. Says the hardest part is starting off, getting the bike leaned right & stable on her good leg to lift the stand.... Has disabled plates on it too

 

[Guest]

There is a member here in California who shifts a 79 850G with a prosthetic leg. She has a heel & toe shifter fitted & carries a hook to lift the sidestand. Says the hardest part is starting off, getting the bike leaned right & stable on her good leg to lift the stand.... Has disabled plates on it too

That's awesome. We have a rider at our local track who was paralyzed while racing bikes in 1994 - and is still fast as hell. I've had the honor of being passed by him numerous times on track days. Nothing but the utmost respect to those who live their lives to the fullest regardless of their injuries.

 

[wyly]

Hey gang, I'm back at the GS1000 restomod game after a number of years away. Good to be back at the GSR! Hope everyone is well.

My old build thread starting back in 2006 is here, but now that the GSR has a Projects/Rebuilds section, thought I'd start up a new thread to share current progress on this build.

Mods include:

Engine/air/fuel/electrical
Wiseco 1100 cc overbore piston kit
Web Cam .395 lift camshafts
GRC welded clutch basket w/ APE hardened clutch hub nut
Oil pump with uprated oil pump gears for higher flow
Dyna coils/spark plug leads
Mikuni RS flatslide carbs
Pingel fuel tap
1989 GSXR 1100 4-2-1 header modified to bolt up to the GS1000 head
Electrosport stator and R/R

Suspension/brakes/controls
2004 GSXR 1000 front end, resprung to 1.0 kg/mm Racetech springs to account for bike/rider combined weight
Monoshock conversion with 2006 GSXR 1000 swingarm and GSXR 750 rear wheel
520 chain conversion
Goodridge steel braided brake lines
GSXR rearsets



I've changed the rear wheel to a 2006 GSXR 750 for better chain alignment. More on that later...

How similar is the frame of the 80GS to a 84 1150E? I'm curious as to how difficult the suspension conversion was, was it a straight swap or require minor mods? Up to now I've only been looking at early 90's GSXR for a suspension swap I didn't think the 2000s Gsxr's were in play.
I've similar plans for my 84 but at this point I'm still gathering data in order to know what parts/donor bikes I'm looking for.
Fork length is a definite problem.

 

[salty_monk]

Totally different.... It's very close to the GS750ES though & I fitted a 5.5" wheel using the stock swinger (slightly stretched & 170 tyre). The more common swap is a 4.5" wheel & a 160

GS Rally July 2010 Drew 033 by salty_monk, on Flickr

GS Rally July 2010 Drew 027 by salty_monk, on Flickr

 

[Guest]

How similar is the frame of the 80GS to a 84 1150E? I'm curious as to how difficult the suspension conversion was, was it a straight swap or require minor mods? Up to now I've only been looking at early 90's GSXR for a suspension swap I didn't think the 2000s Gsxr's were in play.
I've similar plans for my 84 but at this point I'm still gathering data in order to know what parts/donor bikes I'm looking for.
Fork length is a definite problem.

As Dan mentioned the frames are totally different. For the front end on mine, I used a set of conversion bearings (check out All Balls Racing) to bolt on the GSXR 1000 triples. The neck of the frame required welding on some new steering stops.

Once the GSXR front end is bolted on, you need to address the fact that late model GSXR forks are much shorter than GS forks, which can lead to ground clearance and handling issues. I plan on adding some fork cap extenders soon to address this and raise the front ride height 20-30 mm.

The stock GSXR 1000 fork springs were too soft at 0.85 kg/mm so I swapped them out for 1.0 kg/mm Racetech springs.

On my GS1000, the stock speedometer drive was on the front wheel, so an aftermarket speedometer is needed.

Also GSXR front ends run clip-ons stock, so if you want to use regular handlebars you need a handlebar conversion kit like the one I use from Spiegler or potentially drill/tap the upper GSXR triple clamp for handlebar risers.

 

[Guest]

Rear wheel chassis and chain alignment


One of the goals of this revision to this build is to get the rear wheel chassis and chain alignment as true as possible for optimal handling and chain/sprocket wear.


In the previous version of this build, a 2005 (K5) GSXR 750 rear wheel was used in the 2006 (K6) GSXR 1000 swingarm. Rear wheel chassis alignment was good with this wheel as the bike steered straight and true without any pulling to the side. Chain and sprocket alignment was not so great with this wheel however as the assembled wheel hub and sprocket carrier were about 10 mm too wide. To combat this, I had the sprocket carrier posts machined down where they contact the rear wheel hub and shaved the cush drive rubbers to bring the rear sprocket inward. This improved the chain run but in turn caused another issue because now the taper on the posts on the back of the sprocket carrier no longer matched the contours of the wheel hub, causing some good old fashioned metal on metal contact, chowdering the hub.


Ugh. No bueno.

On the bright side, the K5/K6 GSXR 600/750 rear wheels have the same 28 mm axle diameter, 220 mm diameter rear brake rotor, are both 5.5x17", and even use the same wheel spacers on the brake and sprocket side of the rear axle. The crucial difference​ is that the stock, unmodified K6 600/750 wheel is about 9-10 mm narrower at the sprocket carrier/wheel hub than the unmodified K5 wheel.


So, for prototyping purposes, I bolted up a spare damaged (bent lip) 2006 GSXR 750 rear wheel I had on hand into the K6 GSXR 1000 swingarm. It bolted up easily since the axle/spacer/brake rotor dimensions are the same.


Then I started checking alignment chassis and chain alignment using this K6 750 wheel.


The old rear tire currently mounted on this spare wheel is 225 mm across, as measured with a soft tape measure going across the tread from one edge of the sidewall to the other. I marked the tire at 112.5 mm and then shot a crosshair laser level pointing at that mark to see how it lined up with the center of the backbone of the frame.


Excellent Smithers, excellent.

Then, because lasers, I checked the chain alignment. Also looking good. I'm using a 5/8" offset 520 pitch front sprocket, a DID ERV3 520 chain, and Vortex K6 GSXR 750 520 pitch 48 tooth rear sprocket in this setup. IME, 5/8" is the maximum front sprocket offset you can run in a GS1000 frame with a 520 chain before the chain rubs on the frame.

Because of the width difference between the K5 & K6 GSXR 750 wheel hubs, there is now a gap between the sprocket side spacer and the swingarm. I'll need to get a new sprocket side spacer made up to fill in the gap. I also ordered a used, good condition K6 GSXR 750 rear wheel to replace the damaged one used for prototyping.

 

[salty_monk]

Looking good... nice to see the plan coming together

 

[Guest]

CAD drawing for the needed M28x39x30 sprocket side spacer. Now just need to find a shop who can CNC this simple spacer from some 6061 aluminum without charging a kidney as compensation. Any ideas?

 

[Guest]

Welp, the online and local machine shops think that one-off CNC machined aluminum spacers are worth their weight in gold, so another solution must be obtained.

The stock K6 GSXR 750 sprocket side spacer is M28x39x17. I need a M28x39x30 spacer. If a machinist turns down a spare M28x39x17 stock spacer by 4mm in length, then I should be able to stack the stock and modified spacers next to each other to get the spacing needed. Thanks to Salty_Monk for the discussion on this topic offline.