'76 KZ900 (ZRX1200R) Build

NakedFun wrote: Mark,
I know I can get 5/8" pretty easily and was thinking of ordering one through PB Sprockets 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.

I'm running a 5/8" offset sprocket on my 1000. The engine is stock apart from rejetting and a 4-1 exhaust. I'm not running an outboard bearing support and have rode the bike a couple thousand miles and no issues.

If you plan on really beefing up the engine or constantly performing hard launches then I would suggest a bearing support otherwise you will most likely be fine without one.

I also got away with not having to clearance my frame. The chain only rubbed enough to scratch the paint off. But from what I can tell, it's almost a case by case basis if the frame will need clearanced or not.

As for the front brakes, I've heard quite a few guys on a Suzuki forum said they prefer the feel and power of the 4 pot calipers of the 6 pots.

Later, Doug

Considering I am alomost there with a 3/8" sprocket and I know I'll probable run into an issue with 5/8" and frame clearance which I would like to avoid. This leaves 1/2" offset. So if I do 1/2" offset, should I run a bearing support? I spoke with D&G at length this morning and they claim for a street bike, it is really not needed even with 5/8" offset. I don't like doing things that are "acceptable" or just "adequate". So I am asking is 1/2' offset really more than adequate or barely? It will be about $320 for a 1/2" sprocket with bearing support kit from D&G....

Cory

Well I am sending my 3/8" sprocket along with my stocker to leon for modification to 1/2". Will just run it without the outer support. WTH....

I also think I may run the 4 pot NISSINs on the front. I have 4 pot Tokico's coming for trying on my ZRX. If I like them, I'll run the 4 pots for sure.

Cory

i'm at work right now so i cant see the pics.
But I would mill the rear hub to get the tire as close to the tire as u feel comfortable, and call it done. Then mount it and work on the front.
Now, set the front exactly in line with the rear. What ever that offset is, have Leon make the sprocket. Done.
Now, if clearance is needed, do it. If not, Done
Simple.
I’m Not trying to sound offensive, in any way, just trying to help, keep it simple.

as for frame clearancing. it was simple. i just heated the inside of the frame with a torch, and then squeezed it in with a large C clamp. 5 minuits work. I also ground off the bottom footpegs frame boss on the inside of the frame.

as for the bearing support. i have run without 1 for a few years now, on the street. i have a fully modified 1200cc motor. I will put 1 on before I drag race it.
when i did my research, the consensus was that street was ok, but for drag racing a support plate would be the smart thing to do. i would think the same advice would hold true for a 1/2" offset.

Mark I do appreciate the feedback, but I think I am going to leave the rear tire where God and Momma Kawi intended it. Honestly, this is the debate that has raged on for years at the ZRXOA site about he handling benefits of the ZRX1100 vs. ZRX1200R due to the offset present in the 1200's rear swing/wheel placement while the 1100's is centered with the front wheel. Am I going to race this bike, probable not. Am I going to go bombing around on it, absolutely. I will have a 1/2" offset front sprocket made up and then mill the rear accordingly which based onthe measurements I have taken, should locate the chain nicely in the middle between the tire and frame.

I say this, but who the heck knows what I may decide tomorrow. It is bike-ADD.

Cory

Just saw this thread, I'm luvin it!

NakedFun wrote: Mark I do appreciate the feedback, but I think I am going to leave the rear tire where God and Momma Kawi intended it. Honestly, this is the debate that has raged on for years at the ZRXOA site about he handling benefits of the ZRX1100 vs. ZRX1200R due to the offset present in the 1200's rear swing/wheel placement while the 1100's is centered with the front wheel. Am I going to race this bike, probable not. Am I going to go bombing around on it, absolutely. I will have a 1/2" offset front sprocket made up and then mill the rear accordingly which based onthe measurements I have taken, should locate the chain nicely in the middle between the tire and frame.

I say this, but who the heck knows what I may decide tomorrow. It is bike-ADD.

Cory

that is interesting. i never knew that.
i started off to set the rear wheel to get it to line up with the front wheel. then i had to tweek things to match the sprocket lines.
in the end i realy dont think it makes any dif , unless u r a top notch racer.
i have taken it to the track (road racing) and could not tell that its not perfectly centered. after u start shitting your pants, when the motor, or pipe hit the ground, u dont pay much atension to the small stuff. :woohoo:

NakedFun wrote:

I love that fender!! What is it off?

Same thing as the forks, a ZRX! Just with a satin black rattle can treatment by the PO.

Cory

Cory,
Thank you for the forks measurement, it is just 1/2 inch shorter than the original (and softer) forks. This thread has quite a lot of very good information and thought process in it, especially the discussions you mentioned about front/rear wheel alignment for the chain clearancing, many thanks. I would go with the 6 pot calipers, more braking surface for such a heavy bike and rider, I weigh 265 myself and will probably get a set for my bike. Front fender looks great as does the paint scheme.

Great project! :woohoo:

ALec

Looking for opinions. New measurements show about .358" between the outside of the chain and the widest part of the tire with the 3/8" sprocket. Now the chain at it .99 degree angle is angled toward the tire...so that should improve slightly with the 1/2" offset Leon is making me. So with the sprocket at 1/2" that puts the chain with .092" clearance to the frame with that extra .125" offset. So if I were to take another .125" - .200" off the hub, that would increase my frame clearance slightly and leave me with approximately.158" of clearance at the tire. This would still leave me with the sprockets out of alignment by .140" over 27.3" chain span. This equates to .3 degrees deflection. Is this OK? If I took that much more out of the hub for a total of .340" that theoretically would only leave me .018" to the tire which seems close. The other option would be to go out to 5/8" front, which means frame interference for sure, but then drop what I need to mill extra out of the hub to .215" from .200". Thoughts?

Cory

I'm in the same boat as Streetfighter KZ.
I run a 5/8" offset sprocket and it to has only removed the paint on the frame.
It does run within 2mm of the tyre and frame. Also without a bearing support.
The motor is a 1327 and has been dynoed at over 125 HP.
The only problem I had was the spline on the sprocket was about 14mm and there is
only 8mm on the output shaft. This resulted in stripping the spline on both the
sprocket and output shaft. Also this increased the offset.
I have replaced both with the same sized sprocket and used a longer output shaft,
Which I was told came out of a 79' model.
The only difference is the spline is 14mm long.