1981 GSX1100 Katana Based Project

[Shin-Ken 1074]

Just noticed in the pic before the aluminium bolts on the scale pic, the catch can support bracket needs to go on a diet. Must be around 25 grams extra weight there?

[Shin-Ken 1074]

Have trimmed the catch can bracket, now 25 grams lighter.

Catch can bracket 1 by Max Mutarn, on Flickr


Catch can bracket 3 by Max Mutarn, on Flickr


Catch can bracket 6 by Max Mutarn, on Flickr

[Shin-Ken 1074]

Also replaced the catch can bracket titanium bolts with aluminium bolts, trimmed bracket and ally bolts are now 30 grams lighter.


Titanium bracket bolts.
Catch can bolts 2 by Max Mutarn, on Flickr


Aluminium bracket bolts.
Catch can bolts 5 by Max Mutarn, on Flickr


Lighter bracket and bolts installed.
Catch can bracket 7 by Max Mutarn, on Flickr



Running tally = 199.602 kg.

[Rob S.]

I remember when Harley boasted in their print ads the heft of their bikes. "A passing 18 wheeler is not going to blow you out of your lane," some thing like that.

Circa early 1970's, IIRC.

[Grimly]

I remember when Harley boasted in their print ads the heft of their bikes. "A passing 18 wheeler is not going to blow you out of your lane," some thing like that.

Circa early 1970's, IIRC.

Amusing that they even entertained the notion that a passing 18-wheeler would be overtaking a bike.

[Shin-Ken 1074]

Shed a few more grams today by replaced some titanium bolts with aluminium bolts, not big savings but every gram taken off helps in the big picture.

ally bolts 1a by Max Mutarn, on Flickr


The aluminium cowl brackets were attached with titanium bolts, replaced them with aluminium allen bolts, much lighter.
ally brackets 1b by Max Mutarn, on Flickr

Also replaced the oil cooler lower deflector bolts with aluminium allen bolts, four bolts weighing 3 grams!

oil cooler defector bolts by Max Mutarn, on Flickr


Running tally = 199.585 kg.

[Rob S.]

Amusing that they even entertained the notion that a passing 18-wheeler would be overtaking a bike.

Going in the opposite direction, IIRC.

[rphillips]

Grim, 18 wheelers didn't normally overtake bikes... but Harleys were different.

[Shin-Ken 1074]

A parcel arrived today.


Mikuni by Max Mutarn, on Flickr


A set of new Mikuni RS 38MM flatslide carbs for the project Kat. Not only would they be helpful in providing some get up and go, they are an amazing looking bit of kit and could well be considered Art!


Mikuni 38 mm a by Max Mutarn, on Flickr


Mikuni 38mm b by Max Mutarn, on Flickr

[Grimly]

Lovely stuff. ............

[Blower]

Nice carbs, but maybe slightly too big for your engine. I had 38 Mikunis on my 1296 cc GSX and they worked quite well. Then I swap the engine to 1360 cc and now the carbs are working perfectly.
I think the 34`s would have been better for you if you are not going to racing.

[Shin-Ken 1074]

Nice carbs, but maybe slightly too big for your engine. I had 38 Mikunis on my 1296 cc GSX and they worked quite well. Then I swap the engine to 1360 cc and now the carbs are working perfectly.
I think the 34`s would have been better for you if you are not going to racing.

Yes, maybe 34 mm flatslides would suit a stock 1135 and I know some who are running those carbs on their Kat. However, fitting 38 mm flatslides is not unusual with the 1135 and over engines in my part of the world. My engine will be running a set of 4-1 Yoshi 60 mm pipes with a 60 mm muffler, Yoshi cams, adjusted timing, velocity stacks and to get it sweet the carbs will be set up using an O2 sensor to sort out the jetting.

Right now the Kat is fitted with 36 mm CV carbs with 160 main jets and it is running strong and smooth in each gear all the way up to WOT.

The build focus is weight and not outright performance. If the flatslides are heavier than the 36 mm CV carbs that will pose a problem for me.

[Diirk]

I would be surprised if the flatslides aren't heavier as I've always found them to be "weightier" in my hands than their CV counterparts. But the scale will tell.
Regardless of the weight I'd switch them over because I feel that your end result shouldn't be all about weight, but how you enjoy the motorcycle as a whole. I highly doubt in any case that the carbs will tip you back over the 200kg so the mental aspect of it should still be acceptable

[Shin-Ken 1074]

I would be surprised if the flatslides aren't heavier as I've always found them to be "weightier" in my hands than their CV counterparts. But the scale will tell.
Regardless of the weight I'd switch them over because I feel that your end result shouldn't be all about weight, but how you enjoy the motorcycle as a whole. I highly doubt in any case that the carbs will tip you back over the 200kg so the mental aspect of it should still be acceptable

The numbers are in and it isn't looking good for the flatslides.

The 38mm flatslides, two throttle cables and twin cable throttle = 4,140 g.

The 36 mm CV's, one cable and single cable throttle = 3,172 g.

So changing to the flatslides will add 968 g (and about 10 ponies going by dyno figures from previous 38 mm flatslides fitted to the 1135 engine) and take the weight up to 200.553 kg.

The raw numbers don't tell the full story, the elephant in the room is of course the extra performance of the 38 mm flatslides when compared to the 36 mm CV carbs. However, the Kat being 60 kg lighter than stock, the 36 mm carb jetting set up using an O2 sensor, the Yoshi cams and adjusted timing the Kat is plenty fast enough and has arm stretching acceleration in every gear. The balance and handling are excellent as is the comfort and seating position, for me this is everything I had hoped the project end result to be. So as it stands now, I am very happy with how the Kat rides and performs so I'll put the 38 mm flatslides away for now and keep on enjoying the Kat with the 36 mm CV's. Maybe oneday the 38's will get a run, but not today.

Running tally = 199.585 kg.

[first timer]

just go to the bathroom before you ride the kat with 38's that will get you back to base