1975 KZ 900 , ZRX Swingarm, 89 GSXR front end

your bike look great in orange....


.I also use the light bracket form a 81 kz that mount to the gauges bolts.

Assuming your bike is ready to ride, tank empty is actually the wet weight. Dry weight is without engine oil, fork oil, battery, etc., so your bike should easily be sub-400 lbs dry.

tk11b40 wrote: Weighs in at 440 pounds with half tank fuel. A little heavier than I was shooting for. Wanted to hold it at 425 dry. 2.2 gallons of fuel weigh about 13.75 pounds, which would give it a dry weight of 426.5 pounds. Not bad.

I believe the quoted dry weight for the Z1 was 506 lbs. So you managed to shed close to 100 lbs.

Where did that 100 lbs go? It looks like most everything is still there, even the battery. Plus you added bracing to the frame... Is there that much weight savings in the modern suspension and wheels?

dohc wrote:

tk11b40 wrote: Weighs in at 440 pounds with half tank fuel. A little heavier than I was shooting for. Wanted to hold it at 425 dry. 2.2 gallons of fuel weigh about 13.75 pounds, which would give it a dry weight of 426.5 pounds. Not bad.

I believe the quoted dry weight for the Z1 was 506 lbs. So you managed to shed close to 100 lbs.

Where did that 100 lbs go? It looks like most everything is still there, even the battery. Plus you added bracing to the frame... Is there that much weight savings in the modern suspension and wheels?

Yes. Triple trees are aluminum instead of steel, swing arm is aluminum instead of steel, the stock wheels are steel hoops and spokes compared to light aluminum wheels. Then figure on the brakes. Three light discs compared to one heavy one and a real heavy drum brake. The bracing doesn't add much weight at all compared to what was taken out. FWIW that has been my finding on my build.

Cory

Cory,

God question. There are many details, each one looked at rom a weight perspective. My favorite is the rear brake. The rear brake is from a Honda CR450R. The stay, caliper mount and caliper weight bout 7 pounds I think. The actual weight savings are documented somewhere in the 40 pages, so I am going from memory here. The old rear brake set up must have weighed in at 20 pounds.

The rear fender was removed, sounds simple yet there is almost ten pounds in that thing. The front fender is now plastic, more weight savings. There are some Titanium fasteners strewn about as well. I started with points which would effect the bike the most (rotation and unsprung weight) and was buying titanium bolts like a mad man until my wife asked me why 6 or7 bolts would cost 110 dollars. Trying to explain titanium to a financially oriented spouse is no easy task.

The bracing...very interesting also, there was a shit ton of globulas welding on this bike from the factory, along with many mounting points which are no longer needed. I removed all of the tubing (passenger peg mounts-etc.) that I could with out affecting the structure. The I added the extra bracing. For an entire winter I was grinding welds down, to make them nice "fillets" nstead of globs. I even swept up the shaving after a day of grinding, they actually weighed about half pound. The bikes were so overbuilt back then, that there are all kinds of places you can reduce weight.

I have some material picked out at work, and if the shop ever slows down, I will be making titanium axles. Many many little things turn into grams, then ounces, then pounds.

Funny.. I posted the photo, and forgot I had a lightening hole pattern drilled into the spacers for the rear brake, you can't see them unless you remove the axle and brake. I forgot they were there.... :laugh:

Anyway there is another example of a few grams here and there.

Here is a shot of the whole rear brake with stay, and master cylinder in view.

Even the diameter and thickness of the rear brake rotor was reduced to match the size of a 450 Honda, there was about a pound taken out there.

The flatslide carbs also reduced overall weight.

wow....that rear looks awesome...Carbs even better :woohoo:

Well I finally sorted out the gage lighting issue. the 75 KZ has a single turn signal indicator light in the gage cluster, the 76 LTD 900 has a left and right indicator. I am using 76 LTD gages. Before I discovered this, when I plugged the two wires (grey and green) into the bikes 9 pin, the turn signals would get real wacky. I don't understand it totally but at least its sorted out now.

So I pulled the left and right wires out of the 9 pin connector, I will make jumpers from the turn signals themselves to get that to work right. I already tried it with temporary jumpers.

Everything works now, just waiting to collect enough cash to buy some headlight brackets.

tk11b40 wrote: Well I finally sorted out the gage lighting issue. the 75 KZ has a single turn signal indicator light in the gage cluster, the 76 LTD 900 has a left and right indicator. I am using 76 LTD gages. Before I discovered this, when I plugged the two wires (grey and green) into the bikes 9 pin, the turn signals would get real wacky. I don't understand it totally but at least its sorted out now.

The turnsignals were back-feeding through the indicator light. A couple simple diodes might fix the problem.

Later, Doug

If you have your tank painted make sure you don't get all excited when it is time to start up and forget to clean the inside of the gas tank. I just spent a couple hours removing the brand new flat slides, and cleaning some kind of black goop out of them. It was a very small amount, just enough to totally plug two pilot jets. just sayin'.

I have to assume it was sanding dust inside the tank, then mixed with gasoline. I am now putting on two very fine fuel filters, followed by a tank rinse that I should have done the day I got it back from the painter.

:ohmy: