1981 GSX1100 Katana Based Project

[Shin-Ken 1074]

I bought a Katana seat and bodywork fibreglass shell for the project, lighter than OEM parts and a fraction of the cost of buying a seat and bodywork. The shell is a bare item and not supplied with brackets or mounting points. Made the front seat bracket from flat aluminium and folded/welded to copy the profile of the OEM steel seat bracket. For the rear used the OEM seat lock, no extra bolts or clips needed to secure the seat shell.

Seat shell 1 by Max Mutarn, on Flickr


Seat shell 2 by Max Mutarn, on Flickr


Seat shell 3 by Max Mutarn, on Flickr

Seat shell front bracket 1 by Max Mutarn, on Flickr


Seat shell front bracket 2 by Max Mutarn, on Flickr


DW seat bracket 1 by Max Mutarn, on Flickr


Seat shell rear OEM lock by Max Mutarn, on Flickr


I used an industrial bonding agent to glue an aluminum flat plate under the seat that engages the front seat bracket in the same way an OEM seat would. This ally flat plate also provides structural support to the seat shell, the shell is pretty thin however, if you want to reduce weight then the thin shell is the trade-off.

The following pic does not show the two locator tabs that have since been welded to the front seat bracket to hold the seat in the correct position.

front seat bracket engaged by Max Mutarn, on Flickr

[Shin-Ken 1074]

I want the project to have the appearance of a stock - ish Kat so I had the shell painted in 1981 SZ colours except for the forward seat area. That section is painted black instead of Royal Blue. The black finish is to blend the seat shell with the black foam seat pad. OEM choke decals and automotive black tape to mimic the OEM black plastic sidecover inserts.


seat shell paint 1 by Max Mutarn, on Flickr


seat shell paint 2 by Max Mutarn, on Flickr


seat shell 4 by Max Mutarn, on Flickr

seat shell 5 by Max Mutarn, on Flickr


Seat bodywork painted by Max Mutarn, on Flickr



seat shell 6 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Aftermarket fibreglass front guard, lighter than OEM ABS plastic guard. OEM guard is made to fit a 19" front wheel and when fitted with an 18" wheel the gap between the guard and wheel looks wrong. Blocked off the original bolt holes and raised the new holes to lower the guard position on the forks and hug the 18" front wheel. I also blocked off the speedo cable rubber guide hole, not needed, trims off a few grams and gives the guard a clean look.

The first pic shows how the new guard position looks married to the 18" GSXR750 wheel. The original mount holes for a 19" wheel and the hole for the speedo cable rubber guide have not been blocked out yet.


lowered front guard by Max Mutarn, on Flickr

guard paint 1 by Max Mutarn, on Flickr

guard paint 2 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Tank is back and the painter did a very good job on it. Prepared it before giving it to the painter and once back I applied OEM decals, one more part done.

Tank paint 1 by Max Mutarn, on Flickr


Tank 1 by Max Mutarn, on Flickr


Tank 2 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Cowl is now back to the original silver for an SZ Kat.


cowl 1 by Max Mutarn, on Flickr


cowl 2 by Max Mutarn, on Flickr


cowl a by Max Mutarn, on Flickr

[Shin-Ken 1074]

Frame, engine and bodywork painting is all done. I am waiting for some bolts to arrive later this week and once they are here the engine cases can be fitted and the tally moved along. Waiting for swing arm paint to cure and then the wheels can be installed and the DW can be taken off the bench and put on the ground for the first time in it's new life. I will then be able to fabricate the aluminium side stand. The OEM stand is an anchor!

[nvr2old]

I have thoroughly enjoyed this thread. Everything you've done looks amazing. The body parts turned out great. Can't wait for next installment.

[Rob S.]

I'm looking forward to the final weigh-in.

[steve murdoch]

Love the look of the raised lettering on the tank.

[Shin-Ken 1074]

I have thoroughly enjoyed this thread. Everything you've done looks amazing. The body parts turned out great. Can't wait for next installment.

Hi Never 2 Old, I agree with you 100% on the body work and the really nice job the painter did. I am very happy with the end result.

Cheers.

[Shin-Ken 1074]

I'm looking forward to the final weigh-in.

Hi Rob, my guess is about 6 weeks from now the scales will have the number for us. The goal is 180kg dry, which would be a 52kg reduction if the 232kg dry weight as stated in the factory manual is correct. However, once up and running I am sure I will find things that can be tinkered with to lighten it a few grams here and there. One area that could shave around 1.8kg is the flywheel and starter clutch. These could be swapped out for parts from an SRAD 600. I have the SRAD parts and an engineering firm (another one) I use are able to modify the flywheel and starter clutch to fit the EF shaft and re-harden the parts after machining. Doing that is for another day, if ever.

Cheers.

[Shin-Ken 1074]

Love the look of the raised lettering on the tank.

Hi Steve,

yeah, the logo looks good. The guy that made the tank does it all by hand, the complete tank including the embossed logo.

Cheers

[Shin-Ken 1074]

Not much to report today, waiting on some bolts to arrive and paint to cure however, could do a bit of show and tell? The Kat is fitted with aluminium clip-ons but they are solid aluminium! This is one of those cases where thin moly-steel is lighter than solid aluminium. I found a set of used hollow moly-steel clip-ons for the Kats 37mm fork tubes and as a bonus they are adjustable! The aftermarket clip-on had an M12 steel allen bolt so I swapped the M12 steel for a Ti 12 point bolt and here is the result.

316 grams lighter for the pair of moly clip-ons.


OEM Ally clip-on by Max Mutarn, on Flickr


Aftermarket moly clip-on by Max Mutarn, on Flickr

[Shin-Ken 1074]

Lithium batteries can go very wrong sometimes, on a ride last year one of the bikes had a lithium battery that exploded on start up! But the YB14LA2 lead acid battery is 4.1kg plus the OEM steel battery cradle. A lithium battery with the same CCA weighs 920 grams. The goal is to reduce weight so the lead acid battery has to go! Turns out the lithium battery I wanted will not fit the OEM battery cradle so a replacement cradle is needed. Aluminium to the rescue.

I cut up some ally angle and flat, gave them some holesaw attention and then sent it out to be welded, much lighter than OEM steel unit.


Ally cradle parts by Max Mutarn, on Flickr


Ally cradle complete by Max Mutarn, on Flickr

[Shin-Ken 1074]

For tolerance fit aluminium parts anodising is the way to go rather than paint however, depending on the finish required, sometimes the parts need to be polished before being anodised.

Lost count of the hours spent with wet/dry 240, 400, and 800 sanding off casting lines and rough surfaces before polishing all the parts.

polished parts pre anodise by Max Mutarn, on Flickr