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1981 GSX1100 Katana Based Project

Numbers time for the fork parts being swapped or deleted, not the total fork weight right now.


OEM anti dive units and hoses.
OEM antidive by Max Mutarn, on Flickr


OEM anti dive hose brackets.
OEM anti hose bracket by Max Mutarn, on Flickr

OEM fork brace, anti-dive units,anti-dive hose brackets and fork springs total = 2,546 grams.
 
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Swapped anti-dive units from OEM to PMC units.


DW antidive by Max Mutarn, on Flickr

OEM 1 x brace, 2 x springs, 2 x anti-dive and hoses and 2 x anti-dive hose brackets = 2,546 grams.


1 x Daytona fork brace, 2 x PMC anti-dive units and 2 x TNK fork springs total = 1,312 grams.


Total weight removed from fork set = 1,234 grams.

This is where having to use the OEM preload units hurt, they are double the weight of the aftermarket preload units.
 
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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.

Are you sure the aluminum spacer tube won't collapse when you tighten the pivot bolt to torque?​
 
Are you sure the aluminum spacer tube won't collapse when you tighten the pivot bolt to torque?​

I would like to think it will be O.K. but until it has been in use and fully tested it is a bit of the unknow right now. The spacer would be difficult to damage because to crush the spacer the frame and swing-arm would need to be distorted when setting the torque on the pivot bolt, an unlikely event. I am not worried if it does suffer damage when in use, sometimes new and untested things work and sometimes they don't. If needed I would just make another one with slightly thicker walls and perhaps smaller bore holes.
 
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I wasn't happy with the carbon screen I made and how heavy it turned out to be. The first couple of screens I made were O.K. but went in the reject pile for various reasons. The weight of the carbon screen for the DW 180 has been bugging me for the last week so I had to do something about it. I have picked out the best of the reject screens I made and will use it for the DW 180. At 99 grams it is 1/3 lighter without the trim fitted and will polish up O.K. for use.

Carbon screen MKII b by Max Mutarn, on Flickr



Carbon screen MKII c by Max Mutarn, on Flickr
 
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Now with new oil and seals the forks are ready to go on. TNK refurbished clocks with the top plate before fitting the forks. TNK clocks are the same weight as OEM clocks because they are OEM clocks with a TNK dial, just with a different look using the white dial.

TNK clocks by Max Mutarn, on Flickr
 
Lightened the engine by a few grams today. When the engine was weighed it was fitted with the stock five OEM steel oil gallery bolts that weigh 29 grams each. There are 3 other oil bolts, two in the front of the block for the oil cooler lines and the sump plug. The oil cooler bolts are an issue for another day however, the sump plug has been replaced with one of the hollow ally bolts as well. The sump has not been installed yet so that bolt is not included in the running tally today.

In total the five hollow aluminium bolts weigh 1 gram more than just one of the OEM steel bolts!


OEM oil bolt 2 by Max Mutarn, on Flickr

OEM oil bolt by Max Mutarn, on Flickr


Replacing the steel bolts with hollow aluminium that weigh 6 grams each.
DW oil bolt by Max Mutarn, on Flickr

DW oil bolt 2 by Max Mutarn, on Flickr

5 x OEM oil bolts = 145 grams.

5 x hollow ally oil bolts = 30 grams.

147,452 g - 115 g = 147,337 g.

Running tally = 147,337 g.
 
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You'll have to chain this bike down at night. Else it'll just float away. :onthego:
 
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