'76 KZ900 (ZRX1200R) Build

u could just try it and see how it works, thats what i did. but in the end it made more sense to copy what ma kawi's engineers had already figured out.

with a non stock setup, it will be impossible to get accurate spring weight info.
i have installed raceteck fork shims and springs, but all of there data is based on the stock geometry of each bike.
u will need to get an opinion from a good tech.

mark1122 wrote: u could just try it and see how it works, thats what i did. but in the end it made more sense to copy what ma kawi's engineers had already figured out.

with a non stock setup, it will be impossible to get accurate spring weight info.
i have installed raceteck fork shims and springs, but all of there data is based on the stock geometry of each bike.
u will need to get an opinion from a good tech.

True, but if you talk with the ZRXOA (I see you're a member there too) they think the stock ZRX suspension/geometry is not sprung for the majority of the riders.....evidently the US public is really fat compared to Japan! lol I am thinking more and more of taking my new upper mounts to the mill, radius them and and weld them into the frame tubes about 2 inches or so down from the junction with the seat rails. I think it is close to where you ended up. Will take the measurements tonight and compare to my ZRX.

Cory

i agree, that goes for most bikes.
i just feel that my rear end (the bikes, lol)feels better/smoother, tracks the road better in the lowered position. it also makes the internal damping work as intended. its more about letting the shock work the modern way as apposed to the old way. when they designed the kz that era ran the shocks more upright. a vertical shock over the axle travels at the same rate as the wheel. 1:1. through there racing efforts they discovered that the bikes handled better when they started giving the shock less travel to the axles. Just look at the race bikes in the late 70’s to early 80’s, they started laying the shock down. this improved the handling. eventually they hit the limit, and went mono with levers to get the ratios way up. and the handling went up with it.

it made a big dif. that I could feel. to me anyways
hard to go wrong if u copy ma kawi.

Need some idea's?

racingcafe.blogspot.co.uk/2012/07/kawasa...900-style-by-rf.html

bluezbike wrote: Hi Cory,

My question about the length of the forks is because I will be building a bike up this winter and I am gathering as much information as I can before I start as I have never done this before.
I followed a discussion earlier in another thread about how important it was to know exactly what one is doing when changing out front ends which in turn can alter the way bike handles, sometimes very badly, not a situation I want to find myself in. Length of forks was a biggie as well as offsets, trail etc. Many thanks for all the replies.

Alec aka Bluezbike

Alec,

30.25" from axle center to flat surface on fork cap.

Cory

OK, so looking at chain measurement. With my 3/8" offset front, I would need to mill the hub 12mm. Now, I have almost 19mm between the backside surface of the rear sprocket, and the outer most seam/sidewall/molding line of the tire. So, I measured a couple of "O" ring chains and they are about 6.3mm thick from the top of the rivet to the inside of the inner link (read: side of sprocket). This means the side of the chain will move 18.3-19mm. This will probable touch the tire.... So question, is it OK to add a shim behind the front sprocket, so I can reduce the hub milling depth so I can keep some clearance between it and the tire? Thinking about calling the sprocket manufacturer and see if they will make me a custom offset. Thoughts?

Cory

r u sure thats right? 19mm (3/4")seems like a lot of space.
what if u were to run a 1/2" or 5/8" off set countersprocket. would that help fix it at the back?
Leon , D&G or PMF can make any offset u need.

750steve wrote: Need some idea's?

racingcafe.blogspot.co.uk/2012/07/kawasa...900-style-by-rf.html

Oh wow... I thought that was a Z1 at first!!! Mad kudos to whoever made that!

I'm curious to see how you like the front end and how much lower the bike is. I'm strongly considering rebuilding my stock front end with RaceTech goodies, but I'd love to swap it out for a ZRX front end.

got my offset sprocket form d&g. they can make you just about anything you need

Ok, so I did some more research.....

I have been reading technical articles from sprocket/chain manufacters that discuss chain alignment. Naturally, if a chain is out of alignment, that is not good. You get accelerated wear, uneven wear, possible chain derailment, etc... Now they did a study and found that at 3 degrees defelection robbed approx. 4.25 HP when measured on a dyno. So I took some measurements of the current setup as it is, without an correction for alignment besides the front offset sprocket.

The plane to plane difference is 12mm (.47") in order to put it into perfect alingment. Now like I stated above, it appears with the "o" ring chain stacked plate thickness, I will be at an additional 8 mm toward the tire. Currently I have about 19 mm of clearance, so I have a conflict of 2 mm (1mm for the difference, and another for min clearance). So with a cetner to center distance of 27.25" and a displacement of .47" it looks like I am just shy of 1 degree (.99) of deflection. Is there an acceptable angle of deflection? Less than 0.5 degrees? Just thinking if I mill the hub as far as I can without running the chain into the tire and letting the rest of it be? What about adding the difference into the shim and placing it behind the front sprocket? Thoughts?

Cory

Mark,

I know I can get 5/8" pretty easily and was thinking of ordering one through PBSprockets where I got this one. Very nice part and inexpensive. My fear is two fold:

1. Frame clearance: It seems like everyone who runs the 5/8" offset has to clearance the frame.
2. Outer Bearing Support Required: I really don't want to have to run an outer bearing support.

If I have leon make me a 1/2" offset which would atleast get me out of the tire rub issue, I would still have to check on the frame clearance though. Would I need an outer bearing support for that as well? Thoughts comments concerns?

Cory

Also took some pics outside so I can get an idea of the current stance.





In addition, need to decide on two different sets of front calipers.

6 pots:


4 pots:


Comments? Thoughts?

Cory