1981 GSX1100 Katana Based Project

[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

 

[Diirk]

Anodising is in it's own right a weight reduction in comparison to a "traditional paint". Love the work you're doing.
I've had the same idea for my Honda CB1, which I'd like to get to a ratio of 1hp for every 2kg.
Oversized pistons, flatside carbs and nc23 cams could boost the engine numbers, but I could never imagine how to shave off another 30-40kg.
Now I know... and I'll probably keep dreaming about it instead of doing it :witless: So all the more fun of seeing someone go for it!

 

[Shin-Ken 1074]

Anodising is in it's own right a weight reduction in comparison to a "traditional paint". Love the work you're doing.
I've had the same idea for my Honda CB1, which I'd like to get to a ratio of 1hp for every 2kg.
Oversized pistons, flatside carbs and nc23 cams could boost the engine numbers, but I could never imagine how to shave off another 30-40kg.
Now I know... and I'll probably keep dreaming about it instead of doing it :witless: So all the more fun of seeing someone go for it!

Hi Diirk, going by your numbers it looks like your dream CB1 would incorporate performance and weight reduction, a very worthwhile goal for any bike. With bike weight reduction you could do it in stages rather than as a complete project all at once. Think about what parts of your CB1 could be lighter, see what it would take to lighten or change the part and if the cost is within budget.

Slowing it down to perhaps one part per month over two years would keep the workload and cost under control.
Hope you do decide to make a project of your CB1, could be just the bike you want it to be?

Cheers.

 

[Shin-Ken 1074]

The rear brake caliper torque brace has proved to be a big winner or more correctly a big weight loser. OEM steel brace and steel bolts v DW ally brace and Ti bolt.

438 g v 69 g, As a percentage of reduced weight this is one of the best results for the project.

DW caliper 30 by Max Mutarn, on Flickr

Brace only uses one bolt where it is attached to the caliper . The upper section of the brace is welded to the caliper bracket.



Ally brace bolt & washer by Max Mutarn, on Flickr



DW OEM torque brace 1 by Max Mutarn, on Flickr

 

[Shin-Ken 1074]

Where the budget allows, titanium bolts are being used for the project to reduce weight in some areas as well as maintaining the required tensile strength of bolts to do their job. However, there are some places that don't need "rated" bolts to secure the part. Parts like the tappet cover, sprocket cover and clip-on end weights. For these parts aluminium bolts will do the job and be much lighter than titanium bolts.

There is also one place that doesn't even need the strength of an ally bolt, the shark fins under the cowl. O.K. OEM shark fins have captive steel bolts molded into the fin structure so using OEM fins is not helping. I made a set of carbon fins to replace the OEM rubber fins and steel bolts. The carbon fins only weigh a few grams and for super light weight bolts to go with the carbon fins, hollow nylon bolts!

 

[Shin-Ken 1074]

APE aluminium tappet cover bolts and aftermarket Ti tappet cover shoulder bolts v OEM steel tappet cover bolt set.


OEM tappet cover bolts by Max Mutarn, on Flickr

DW tappet cover bolts by Max Mutarn, on Flickr

 

[Shin-Ken 1074]

These aluminium sprocket case bolts are so light, the packaging they arrived in weighed more than the bolts.


Sprocket case ally bolts by Max Mutarn, on Flickr

 

[Rob S.]

Excitement is building around this build, that's for sure. Can't wait to see the finished bike.

I see you're using the Suzi '1150' engine (1135 ccs?). One thing (2 things) that concern me are the bar end weights, standard on new 1150s to mitigate some of the model's notorious vibration. Adding dead weight to a bike has always bothered me, and I wondered how you were going to address this situation.

I'm also concerned that it doesn't turn out looking like Swiss cheese, with holes drilled through everything, but I'm confident you won't permit that.

And lastly, I'm still curious about the $ commitment. I know it's a labor of love, and you could not possibly sell it for a profit. A bike like this doesn't get sold, it gets bequeathed.

 

[Shin-Ken 1074]

A stock Kat GSX1100S (and GSX1135 EF) has factory clip-on bar end weights to help reduce felt vibration through the bars at certain speeds, in many cases at a speed of 100 kph and 3,750 RPM in top gear using an OEM 15/42 sprocket combination for a final drive ratio of 2.80. In my experience I have had success in eliminating bar buzz by swapping sprockets to a 17/51 combination to change the final drive ratio to 3.00. This combination increases engine RPM by 250 at 100kph in top gear so no real need for heavy bar weights now the buzz has gone. The clip-on bars still need something on the end of the bar but now aluminium can do the job.

Found a set of used aluminium racing bar weights in Japan. Swapped the steel bolt for an aluminium bolt and Ti nut and now have a tidy, light weight bar weight set up.

Looking at the bar weights it may not seem worth the effort to swap for ally units however, swapping the two bar weights does reduce the weight by a significant amount.

2 x OEM bar weight units = 350 grams.

2 x ally bar weight units = 74 grams.



OEM steel bar weight and bolt by Max Mutarn, on Flickr


DW ally bar weight & ally bolt ti nut by Max Mutarn, on Flickr

 

[Shin-Ken 1074]

Where it is safe to use aluminium bolts to replace steel to reduce weight does make a noticeable difference. The ally bar weight bolt and Ti nut.

bar weight bolt and Ti nut by Max Mutarn, on Flickr

 

[Shin-Ken 1074]

Excitement is building around this build, that's for sure. Can't wait to see the finished bike.

I see you're using the Suzi '1150' engine (1135 ccs?). One thing (2 things) that concern me are the bar end weights, standard on new 1150s to mitigate some of the model's notorious vibration. Adding dead weight to a bike has always bothered me, and I wondered how you were going to address this situation.

I'm also concerned that it doesn't turn out looking like Swiss cheese, with holes drilled through everything, but I'm confident you won't permit that.

And lastly, I'm still curious about the $ commitment. I know it's a labor of love, and you could not possibly sell it for a profit. A bike like this doesn't get sold, it gets bequeathed.

Hi Rob, you and I had the same thought at the same time (post time stamp 07:51 today) regarding "bar buzz". No problem with that as you can see in my previous post I have managed to eliminate the buzz by changing engine RPM and changing harmonic vibration zone.


Don't forget the 1135 EF engine is now in a Kat frame running 18" front and rear wheels and the Kat doesn't know it is now running an EF engine so there are none of the vices of the GSX 1135 EF with this build. Transplanting 1135 EF engines into Kat frames here in Oz is a well worn path and doesn't generate any problems.

There are a couple of parts and places that have to be drilled rather than reshaped or replaced however, only a couple of Swiss Cheese parts and not really noticeable. One exception is the electric steel panel, that now looks like holes held together with metal rather than metal with holes drilled in it! Pretty difficult to reshape or file a flat sheet of metal so drilling was the only answer to reduce weight.

Notice the shiney spacers in the smaller than stock cut down mounting grommets? Replaced the OEM steel spacers with aluminium tube cut to size.


Regarding cost, not in the bargain basement but less than the price of a used 1981 Katana SZ 1100 in great condition here in OZ.

DW Elect panel by Max Mutarn, on Flickr