1981 GSX1100 Katana Based Project

[Pewpew82]

The exhaust system for the DW had steel header flanges fitted when I bought it so they had to go. Didn't want to damage the headers using an angle grinder with a cutting disc so used a hacksaw blade and slowly worked through each flange. No damage done.

Four of these and eight steel bolts, 840 grams total.

Technically, would the original weight be slightly more than the aforementioned 840 grams only since you are not measuring the removed materials from the saw? Maybe closer to 850 grams by my estimation?

Either way, I am fully invested in seeing the final product and thoughts after riding it. You are doing great work.

[limeex2]

Without going through the whole post, not sure what carbs you are using, just putting it out there. GSXR1100 flat slide carbs weigh 4.5lbs and stock GS1100E carbs weigh 7.7lbs. and add H.P. Stock seat weighs 13.4 lbs, a race seat I have like the original Cooley bike weighs 6.8lbs. For us people on a budget, or using spoked wheels, look up how adventure touring guys are using 3M tape on spoked wheels to eliminate inner tubes. Tube I had been using was 2.3lbs which is unsprung weight. Sorry I'm late to the post and if if I am repeating others.

[Shin-Ken 1074]

Full titanium exhaust, I presume?

Bingo!

Ti pipes, aluminium flanges, Ti header bolts, Ti and carbon muffler, all used parts except the bling Ti bolts. Working on the muffler bracket. The muffler was cheap to buy as it had been in a prang and was in a pretty poor state. Needed some work to get it sorted and able to do its job.

Aluminium flange and Ti bolts by Max Mutarn, on Flickr


Ti pipes Ti and carbon muffler by Max Mutarn, on Flickr

[Shin-Ken 1074]

Technically, would the original weight be slightly more than the aforementioned 840 grams only since you are not measuring the removed materials from the saw? Maybe closer to 850 grams by my estimation?

Either way, I am fully invested in seeing the final product and thoughts after riding it. You are doing great work.

You have the right line of thinking there, chase every gram! As much as I would like to have the saw swarf to weigh 10 grams, experience has shown those eight fine cuts would have produced about 1 gram.

[Shin-Ken 1074]

Without going through the whole post, not sure what carbs you are using, just putting it out there. GSXR1100 flat slide carbs weigh 4.5lbs and stock GS1100E carbs weigh 7.7lbs. and add H.P. Stock seat weighs 13.4 lbs, a race seat I have like the original Cooley bike weighs 6.8lbs. For us people on a budget, or using spoked wheels, look up how adventure touring guys are using 3M tape on spoked wheels to eliminate inner tubes. Tube I had been using was 2.3lbs which is unsprung weight. Sorry I'm late to the post and if if I am repeating others.

Each of the parts you have mentioned have been looked at and taken care of. All of those parts will be replaced with lighter parts, details are listed in earlier posts.

For example the OEM seat, ducktail and side covers have been replaced with a unit that has a total weight of 2,800 grams (5.52 lbs).

DW 180 seat bodywork by Max Mutarn, on Flickr



DW seat bodywork weight by Max Mutarn, on Flickr

[Shin-Ken 1074]

DW 180 Swing arm is now finished, hollow pivot bolt and Ti nut, ally bearing spacer, hollow axle and Ti nut, ally chain adjusters and Ti bolts. DW swinger at 1,670 grams lighter is another step forward in the build.

SZ OEM swing arm = 5,620 grams


SZ OEM swing arm w by Max Mutarn, on Flickr


DW 180 swing arm = 3,950 grams.



DW swing arm complete by Max Mutarn, on Flickr

[Shin-Ken 1074]

DW180 swing arm, new shock bushes, aluminium chain adjusters with Ti bolts and hollow axle.


DW swinger ally adjusters hollow axle by Max Mutarn, on Flickr

[Rijko]

Love the attention to detail, just goes to show many small savings add up.
Curious about the end result, haven't kept count but feels like you will surpass the 50KG goal easily.
Respect.

[Shin-Ken 1074]

Love the attention to detail, just goes to show many small savings add up.
Curious about the end result, haven't kept count but feels like you will surpass the 50KG goal easily.
Respect.

Yes, chipping away at many of the smaller and seemingly insignificant parts is a big help in reducing weight as each part contributes to the end goal. While the big ticket items like pipes, wheels, battery, seat, clip-on bars and weights, brake rotors, sprockets, chain, chain guard, center-stand and side-stand are the go-to parts of the reduction plan, there is a lot of weight savings to be had by including as many of those smaller parts as possible even down to bolts and washers.

When these bikes were designed and built weight was not at the top of the check list so parts like pivot bolts and bearing spacers were made the way they had always been made - with solid steel, tough, reliable and heavy! Thankfully a hollow pivot bolt and an aluminium bearing spacer will do the same job at less than half the weight.

Yeah, the OEM bearing spacer is pretty sad. It came with the donor swing arm and thankfully all I needed was the swing arm.

OEM steel pivot and bearing spacer by Max Mutarn, on Flickr


Hollow pivot and ally spacer by Max Mutarn, on Flickr


The best weight saving is when parts can be deleted completely rather than modified or swapped. A couple of kg have been saved by deleting parts completely:

Anti-dive unit top section, hoses and brackets
Front brake hose manifold
Front wheel speedo dust cover
Front guard speedo cable rubber guide
Wire speedo cable guide on fork lower
Fork OEM steel brace
Centre-stand
Tool roll bracket
Number plate bracket
Rear guard sub-frame
Rear foot pegs
Air box and filter
AUX 12 volt switches
Helmet lock and bolts
Lift handle and bolts
Seat strap




The goal is 180 kg from a starting point of 232 kg and at this stage it is in the low 180's however, I don't think those last few kg are going to be easy to find. I like your confidence and I hope you are right.

[Shin-Ken 1074]

A 630 42 tooth steel sprocket. That can not stay!

630 48 T rear sprocket by Max Mutarn, on Flickr

520 48 tooth aluminium sprocket, much better.

DW rear sprocket by Max Mutarn, on Flickr

[Shin-Ken 1074]

OEM 630 15 T front sprocket/nut.

OEM front sprocket by Max Mutarn, on Flickr

DW 520 17 T front sprocket/spacers/nut.

DW front sprocket by Max Mutarn, on Flickr

[Shin-Ken 1074]

OEM rear wheel spacers.

OEM rear spacers by Max Mutarn, on Flickr

DW aluminium rear wheel spacers.


DW rear spacers by Max Mutarn, on Flickr

[Shin-Ken 1074]

Replaced the sprocket carrier steel bearing spacer with an aluminium spacer. Also replaced the rear wheel inner bearing spacer with an aluminium spacer, no pic of that spacer, sorry.

Carrier bearing spacer by Max Mutarn, on Flickr

[Shin-Ken 1074]

The OEM rear rotor mass and the amount of inertia exerted by it when rotating would be similar to having an extra flywheel attached to the bike. There are lighter alternative rotor options available so out with the old and in with the new.

1,612.8 grams lighter not only reduces weight it will reduce rotating mass. As a very light (hardly ever) rear brake user the heat sink effect of a heavy rotor provides no benefit for this build. These light rotors have been used on 1100cc and other bikes for many years here without any problems in brake performance.

SZ OEM rear rotor by Max Mutarn, on Flickr


DW rear rotor by Max Mutarn, on Flickr

[Shin-Ken 1074]

The rear brake system components are now accounted for except for the new brake line. So comparing the SZ OEM brake system to the adapted GSXR 1000 brake system and aftermarket parts how did it turn out? In the end pretty good, the DW system is less than half the weight and that is not including the difference between the six OEM steel rotor bolts and the five Ti rotor bolts now installed that only weigh 8 grams each. I don't have any OEM rotor bolts so can not compare them to the Ti bolts.



Ti rotor bolt by Max Mutarn, on Flickr


Total weight for the SZ OEM system = 5,126 grams, not including rotor bolts.

Total weight for the DW Project parts = 2,349 grams, not including rotor bolts.

Some of the parts and weights have been shown in previous posts however, the caliper and master cylinder weren't.

Parts details:

OEM brake pedal = 271 grams. DW brake pedal = 120 grams
OEM brake pivot = 257 grams. DW brake pivot = 173 grams
OEM rear master cyl = 433 grams. DW rear master cyl = 218 grams
OEM torque brace = 438 grams. DW torque brace is incorporated with the caliper bracket.
OEM caliper and bracket = 1583 grams. DW caliper/ bracket/ torque brace = 1307 grams
OEM rear rotor = 2,144 grams. DW rear rotor = 531 grams



SZ OEM caliper and bracket by Max Mutarn, on Flickr


DW caliper torque brace bracket by Max Mutarn, on Flickr


SZ OEM rear master by Max Mutarn, on Flickr


DW rear master by Max Mutarn, on Flickr