1981 GSX1100 Katana Based Project

[Shin-Ken 1074]

DWhorn a9 by Max Mutarn, on Flickr


DWhorn a6 by Max Mutarn, on Flickr


DWhorn a8 by Max Mutarn, on Flickr


DWhorn a7 by Max Mutarn, on Flickr


DWhorn15 by Max Mutarn, on Flickr


DWhorn11 by Max Mutarn, on Flickr

[Shin-Ken 1074]

DW horn a5 by Max Mutarn, on Flickr


DW horn a1 by Max Mutarn, on Flickr


DW horn a3 by Max Mutarn, on Flickr


DW horn a4 by Max Mutarn, on Flickr



Bracket is now ready for paint and those bolts in the pic are not the bolts that will be used for the finished bracket.

My estimate of 246 grams for the new horn and bracket were a bit off.

I just noticed in the 2nd last pic the outer edge of the bracket can be trimmed to match the cowl bracket.

[Shin-Ken 1074]

Trimmed the outer edge and hogged out the bracket to match the cowl bracket hole. Bonus - 1 gram lighter. 1 gram doesn't sound like much but it is the percentage removed from each part that adds up to the weight reduction overall. In this case 1 gram is just under an 8% reduction in weight.

DWhorn18 by Max Mutarn, on Flickr



Bracket 1 by Max Mutarn, on Flickr


bracket2 by Max Mutarn, on Flickr

[Rob S.]

With the focus on shedding weight above all else unfortunately performance had to take a backseat on this build. However, with an improved power to weight ratio there will be some gain in performance. I think it would be a struggle for high nines or even 10's and 11's but whatever it could do would still be fun?

Remember that a box-stock 1983 11ES was the first bike that Cycle World got into the tens (just barely - 10.99). The difference was the 'bikini' fairing.

With a larger engine, and much less weight, your Kat should easily do mid tens. Unless, of course, you're a 500 pound fat slob or measure your self in kilograms, whatever those are.

[Shin-Ken 1074]

Remember that a box-stock 1983 11ES was the first bike that Cycle World got into the tens (just barely - 10.99). The difference was the 'bikini' fairing.

With a larger engine, and much less weight, your Kat should easily do mid tens. Unless, of course, you're a 500 pound fat slob or measure your self in kilograms, whatever those are.

Kilograms - whatever those are.

I am 94 KG so a bit less than 500 lb, before Christmas and New Years anyway!

[Rob S.]

I am 94 KG so a bit less than 500 lb, before Christmas and New Years anyway!

I've just discovered an area for additional weight savings!

[Shin-Ken 1074]

I've just discovered an area for additional weight savings!

No way, I am not giving up ribs and beer over Christmas!

[Shin-Ken 1074]

Headlight surround today, usual suspect - aluminium.

surround 1 by Max Mutarn, on Flickr


surround2 by Max Mutarn, on Flickr


Surround in primer.
surround5 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Swapping the OEM steel rear indicator brackets for aluminium brackets.


rear indicator bracket 1 by Max Mutarn, on Flickr


rear indicator bracket 2 by Max Mutarn, on Flickr


rear indicator bracket 3 by Max Mutarn, on Flickr


rear indicator bracket 4 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Swapped the rear reflector for a lighter (and brighter) version.

RR1 by Max Mutarn, on Flickr


RR2 by Max Mutarn, on Flickr


RR3 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Aluminium rear indicator brackets in primer.

rear indicator brackets 5 by Max Mutarn, on Flickr


Head light surround Satin Black to match the cowl head light Satin Black area.

head light surround satin by Max Mutarn, on Flickr

[Shin-Ken 1074]

While the primer and Satin dry, time to make the exhaust to frame bracket so it's back into the off-cuts pile of goodies. Must be something in there I can use?

offcuts1 by Max Mutarn, on Flickr


offcuts2 by Max Mutarn, on Flickr


offcuts3 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Found just the thing! A thin yellow zinc steel strap with pre-punched holes, perfect.


Ex bracket 1 by Max Mutarn, on Flickr


Ex bracket 2 by Max Mutarn, on Flickr


For the bracket gasket I'll make one from a wood fireplace chimney silicone boot.

Ex bracket 3 by Max Mutarn, on Flickr


Ex bracket 4 by Max Mutarn, on Flickr


Ex bracket 5 by Max Mutarn, on Flickr


Ex bracket 6 by Max Mutarn, on Flickr


Ex bracket 7 by Max Mutarn, on Flickr


With the silicone gasket in place, used a bar to align the bolt holes. To much tension on the bracket to try this by hand. Makes for a very secure bracket around the pipe doing it this way.

Ex bracket 8 by Max Mutarn, on Flickr


Ex bracket 9 by Max Mutarn, on Flickr






To keep it light and tidy will mount the pipe bracket to the frame using one of the footpeg bolts, no extra hardware needed.

Ex bracket 10 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Pipes are on and look O.K. So the important news now is the weight of the total system.


Headers/collector and frame bracket.
Zorst 1 by Max Mutarn, on Flickr


OEM gaskets, header bolts and washers, aluminium flange clamps.
Zorst 2 by Max Mutarn, on Flickr


Carbon/Titanium muffler and clamp.
Zorst 3 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Total exhaust system weight = 3,328 grams.


Zorst 4 by Max Mutarn, on Flickr


Zorst 7 by Max Mutarn, on Flickr




Bracket trimmed to fit behind the footpeg mounting plate.
bracket trimmed by Max Mutarn, on Flickr




The yellow zinc finish on the bracket blends in well with the titanium pipe.

Zorst 8 by Max Mutarn, on Flickr


Zorst 6 by Max Mutarn, on Flickr





Muffler fit is nice and tidy and hugs the swing-arm like it was designed for the build. I bought the muffler used and it had been damaged in a prang with road rash and cracked carbon at both ends of the can. Trimmed the carbon and reshaped the damaged titanium end caps and put it back together with aluminium rivets and straps.

Zorst 5 by Max Mutarn, on Flickr


Running tally = 182,995 grams.