1981 GSX1100 Katana Based Project

[Rob S.]

I notice you had a Supervisor next to the ladder checking the GS, it is no wonder the Supervisor is checking out the bike, the 1150 is an amazing engine and considered by many to be the best air-cooled transverse 4 cylinder engine Suzuki ever made.

Notice that even that 'Kat Foreman' knows better than to walk under a ladder.

What about the fact that dead weight had to be added to the 1150 handlebars to mitigate the vibration? As our current weight loss champion, doesn't that rub you the wrong way?

[Shin-Ken 1074]

This is the aluminium nut with steel thread insert and the titanium sprocket bolt used with the aluminium sprocket. The total weight of the sprocket with five bolts and nuts = 496 grams.


DW sprocket nut by Max Mutarn, on Flickr


DW sprocket nut 1 by Max Mutarn, on Flickr


DW sprocket nut bolt by Max Mutarn, on Flickr

[Shin-Ken 1074]

Hi John, your Kat restomod 1230 is a great looking machine and with the mods you have done I am sure it performs as good as it looks and it got the Paw of Approval as well! Same thing here regarding the 1150 engine, not so easy to find these days. My focus for the build was weight and only weight and never performance so skinny tyres and a stock 1135 engine was all I needed.

Thanks for the tip on Supersprox, I'll check on their rear sprockets for weight. The rear sprocket I am using is pretty light at 370 grams and I used titanium bolts with aluminium nuts that have a steel thread insert to keep the weight as low as possible.

DW 520 sprocket by Max Mutarn, on Flickr



Cheers,

Glen.

[John Kat]

Quite amazing result for sure! Yes, the 1150 engine is the most powerfull power plant in the Suzuki air cooled range.
I've fitted one also on my 1100 Kat as you will see below.
1100 Katana restomod with 1230 engine - The GSResources Forums.
The supervisor approved it aswell! IMG_2670 small.jpg
These engines are not easy to find here in France not to mention their 36 mm carbs!
With respect to the GSXR first gen wheels, I went for the larger rear wheel to be able to use the larger tire despite the weight.
My favorite tires are the radial Conti Classic Attack that beautifully fit these wheels with an amazing grip.
On the weight saving side, you might still gain a few grams with the Supersprox rear sprocket.
Cheers
John

[Shin-Ken 1074]

Hi John Kat, to use GSX-R G/H wheels is a good option to reduce weight compared to Suzi snowflake wheels. I also went with the GSX-R wheels however, I used the 1985 GSX-R 750 wheels as the 3.5 x 18" rear wheel is lighter than the 1986 GSX-R 1100 4.0 x 18" for five reasons:

1) The 1100 bare rear wheel is heavier than the 750 bare rear wheel due to the extra material for the 4" rim.

2) The 1100 rear wheel is fitted with a larger tyre and that extra rubber weighs more than the 140 x 18" tyre on the 750 rim.

3) The 1100 rear wheel has five bearings compared to the three bearings in the 750 wheel.

4) The 1985 GSX-R 750 hollow axles and hollow pivot bolt fit the Kat frame and are lighter than the stock solid axles and pivot bolt on the SZ Kat.

5) The GSX-R wheels are a Suzi wheel and look right, and as the saying goes, "If it looks right, it is right."

I notice you had a Supervisor next to the ladder checking the GS, it is no wonder the Supervisor is checking out the bike, the 1150 is an amazing engine and considered by many to be the best air-cooled transverse 4 cylinder engine Suzuki ever made!

Cheers.

[Shin-Ken 1074]

I don't understand the conversion from grams to kg? In metric units a kg is 1000 grams.
So eitheir you saved 184 kg or only 18.4 kg which sounds more reasonable and a great accomplishment in any case given that the bare 1150 engine must way around 100 kg.

Hi John Kat, I used grams for the build as many of the parts weigh less than 1 kg so rather than quote kg and grams for the build I just kept everything in grams.

The completed project Kat build dry weight = 184,446 grams, so final dry weight = 184.446 kg

Factory dry weight spec for a 1981 GSX1100S Kat = 232kg.

232 kg - 184.446 kg = 47.554 kg.

Completed project Kat dry is 47.554 kg lighter than a stock Kat.

Every part, from frame and engine down to individual bolts and nuts have been weighed, many parts modified to reduce weight and some parts deleted. Following the build from the start shows where and how weight has been reduced for each part, every grams counts.

I haven't ridden the project Kat yet so handling is an unknown at this stage however, it is so much easier to push around and very little effort needed when running it up the ramp to load it onto the ute.

Cheers.

[John Kat]

As of today the tally is 184,446 grams however, there are a couple of parts that could be modified and shave a few more grams off the current tally, and I mean only a few grams nothing more.

If the Suzi factory manual is accurate, it quotes the dry weight for a 1981 1100 Kat at 232 kg. So using the factory quoted dry weight of 232 kg as the baseline the build is at 184,446 grams which means 47.554 kg has been removed from a stock Kat.

The goal for the build was to shave 50 kg off because 50 kg was a nice round number and gave me a target to aim for and was based on my estimate of what I thought I could do to reduce the OEM weight. At 47.554 kg it has fallen short of the goal however, there are still a few things that could be done like a smaller flywheel and stator and a smaller starter motor. Parts, engineering and cost are the barriers to do these mods right now so they are not on the must do list at this stage.

The low hanging fruit as the Kat stands now are indicators, instruments and mirrors. By swapping these factory parts for lighter aftermarket parts there is 2kg to be saved however, one of the criteria for the build was to have the finished build look like a Kat and to do that factory mirrors, instruments and indicators are a must have so for now they stay.

I would like to think there will be some adjustments here and there so I am not signing off on the build at this stage. The engine has been run but it hasn't turned a wheel yet so there is still plenty to do, not so much with weight but other things to sort out before it is a road going build.


I need to go through the build tally to ensure all is above board with the numbers however, as of today the reduced weight of 47.554 kg = 104.8 lb.

Cheers.

I don't understand the conversion from grams to kg? In metric units a kg is 1000 grams.
So eitheir you saved 184 kg or only 18.4 kg which sounds more reasonable and a great accomplishment in any case given that the bare 1150 engine must way around 100 kg.

[John Kat]

I lift my hat off to you! A couple of years ago, I went through a weight saving program on my GS 1000 ST.
The main modifications were to use GSXR 11 G/H wheels and complete front end.
As far as I remember I must have gained around 14 to 15 kg...
GS 1000 ST weight saving program - The GSResources Forums.
Since then, I moved these components to another GS 1000 fitted with a 1150 engine rebored to 1230 cc.
Here's a picture:
IMG_3105 small.jpg
I've been contemplating the Nitron Shocks but I don't know what technology is inside ?
Emulsion type or Cartridge type?

[Shin-Ken 1074]

While waiting for new throttle cables to arrive it is a good time to check over the carbs. Each of the bowls had some varnish and sediment and each of the float needles had a small layer of varnish. The jets are clear as well as the rest of the carb being O.K. Carbs back together now and waiting for cables.

Removed the drain screws when cleaning the bowls, all good now. Fuel bowl O-Ring, what a great improvement over the old style gaskets.

Carb 1 by Max Mutarn, on Flickr


Carb 2 by Max Mutarn, on Flickr

J.I.S. screw and J.I.S. driver, a great combination.

Carb 9 by Max Mutarn, on Flickr


Float needle with fuel varnish film, cleaned now and re-installed.

Carb 8 by Max Mutarn, on Flickr


Carb 10 by Max Mutarn, on Flickr

[Shin-Ken 1074]

The outer piston seal groove had some hard crusty snot growing in it, so made a groove cleaning tool from a screwdriver. Perfect fit for the groove and going gentle didn't leave any scrapes or scratches.

Caliper tool 2 by Max Mutarn, on Flickr


Caliper tool 3 by Max Mutarn, on Flickr


Caliper tool 4 by Max Mutarn, on Flickr


Caliper tool 6 by Max Mutarn, on Flickr


Caliper tool 7 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Come across many similar looking calipers over the years.
They also have a distinctive terrible smell.

Yeah, pretty common condition for brake fluid. Being a hydroscopic fluid the humidity around here trashes brake fluid fast. I change brake fluid in July each year for all my vehicles.

[Shin-Ken 1074]

Maintenance is overrated.

And cuts into beer time!

[steve murdoch]

Come across many similar looking calipers over the years.
They also have a distinctive terrible smell.

[Shin-Ken 1074]

Popped the pistons using air, they were pretty tight, took 80 P.S.I. to get them out. Hold the caliper with the pistons facing down and a rag between the pistons and caliper body, prevents damage to the caliper body and stops the piston in the rag when it pops out under pressure.

F caliper 6 by Max Mutarn, on Flickr


The P.O.would have had a few interesting times trying to stop in a hurry with these brakes. I don't think these calipers were doing much stopping going by the amount of water and gunge in the bore, the pistons were jammed in pretty firmly!
F caliper 9 by Max Mutarn, on Flickr


F caliper 7 by Max Mutarn, on Flickr


Slide pin retainer growing a new crop of slime.
F caliper 10 by Max Mutarn, on Flickr


After hitting it with degeaser to remove the heavy gunge it's into hot water and detergent for the final cleaning with a soft natural fiber brush to prevent damage to the bore.

F caliper 12 by Max Mutarn, on Flickr


Now it looks like a brake caliper. Well it would if I took a decent pic in focus.

F caliper 11 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Front calipers today. Bought a pair of used GSX 750F calipers for the project so it's time to strip/clean and throw a new piston and seal kit at them. Going by the internal condition Iam guessing the brake fluid hasn't been changed for a few years. Lucky the bores are not pitted so after a degrease and a wash in hot water and detergent the bodies look much better. With new pistons and seals fitted they should operate like new.

External condition not so bad.

F caliper 1 by Max Mutarn, on Flickr


F caliper 2 by Max Mutarn, on Flickr


F caliper 3 by Max Mutarn, on Flickr


Slide pins need a clean and repacking.
F caliper 4 by Max Mutarn, on Flickr


Slide pins cleaned.
F caliper 5 by Max Mutarn, on Flickr