'76 KZ900 (ZRX1200R) Build

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Dang that's a sweet machine. Good work!

Update finally.....! Hunting season is over for me, which allowed me to travel up to the shop and work on the KZ. Got the exhaust done and I like how it turned out. Need to add one stainless clamp and then off to have it ceramic coated (probable satin black).

Here is the midpipe with the first welded bead then ground down to smooth it out.



Here is a shot of the mounting system I made.



Back side view, which shows it is pretty tucked...



Final weld with O2 sensor bung added. Forgive the appearance of the welds.....



Final look with pegs in place.



I also got to try out all my custom lines. Turns out the rear will need to be remade, about 3 inches longer.



Stainless clamps that fit the lines perfect for routing. Drilled and tapped the lower triple for 6mm x 1.0 and added a clamp there. Everything turned out routed nicely.




Now lets talk about what the next challenge is..... I am going to need a chain guide / roller.

I think I am going with this one : www.dimecitycycles.com/vintage-cafe-race...mon-weld-on-spr.html but make it a fixed position. I am finding I need to make a gusset system that mounts it rear of the drive sprocket to ensure the chain always has clearance over the swing arm pivot tube. Thoughts on this? Anyone use these rollers before?

My only concern is that at times, the roller will be preventing the tension side of the chain (top) from going completely straight, and so it will be taking forces from the torque of the engine. i.e. when you throttle the bike, the chain will try and be pulled straight, but this roller will prevent that from completely happening. Concerns? Other than that, having my rear hub milled .200" for alignment and ordering a PMF drag plate for my hydraulic clutch conversion.

Cory

on page 8 of my build i have some info on the roller i built.

kzrider.com/forum/11-projects/103381-76-...e?limit=20&start=140

Mark,

Thanks for the reply. My original comments were about a steel sprocket with a ball bearing in the middle, mounted right in front of the swing arm pivot shaft, just to prevent the chain from touching the swing arm. Since it is not on the slack side, I am worried about it failing due to the loading it may take. May try a larger front and rear sprockets, to get it more clearance.

Cory

oh, sorry. i thought u meant underneath. u meant on top. ok. i just used the stock zrx rubber mount on top. then u had an issue with the top of the chin jumping high and hitting the bolt that hold on the motor mount. since i used a very thick aluminium mount the bottom bolt and the edge of the mount were getting hit buy the top of the chain. so i installed a roller bearing on that bolt. now the chain hits the roller bearing.

i use a 19 x 530 on the front and i think i have a 45 maybe 44 on the back? its the stock zrx12 rear sprocket. i think a 50 rear may give u high rpm's at cruise.

Well right now I have it geared like the ZRX1200 with a 17:45 or a 2.65:1 ratio. If I go with a 50 rear and an 18 front, (18:50) I'll end up with a 2.77:1 which should be fine. My current ZRX1100 is running a 17:47 or 2.76:1 which is dang close.

I tried it with my weight and with my dad's weight (he is much heavier than me) and with him, get about 1/8" clearance. With me, it didn't actually have clearance, but was just touching.

So are you saying you have a roller up top as well to prevent chain to swing touching?

Cory

i have no roller between the top of the arm and the bottom of the chain. just the stock rubber on top of the arm. but i have a 19 tooth sprocket, which helps. i have a roller above the top of the chain.

so 19 x 50 would give u then . about 2.63.
i think i'm at 19 x 45 , or 2.37

keep in mind that a zrx has a sixth gear. when ever i ride my kz at cruise in 5th gear with 19 x 45 i feel like i need 1 more gear.

i just found the top roller pics. a member , tk11b40, had these made for me buy his friend.







on tk11b40's bike



on my bike



i ended up losing that roller at the track. so i replaced it with a simple sealed roller bearing. something like this. just make sure u use a locking nut of some kind. i learned the hard way. i had a nut jambed against the inner part of the bearing but it still came loose.

Mine is similar to Mark's set up. Roller on the bottom, slider on the top of the arm.

Here are a couple of pics that, I hope, show what I'm talking about.

I like the tuck of the pipe.looks like it wont be a issue dragging in corners.only thing I can see is I think the 02 bung would look better under the bike. hidden?

camaroguy wrote: I like the tuck of the pipe.looks like it wont be a issue dragging in corners.only thing I can see is I think the 02 bung would look better under the bike. hidden?

Oh ya, the pipe looks super!! Great work there!! I should have said that sooner!! :ohmy: :laugh:

I may be missing something, but I'm wondering, why the o2 bung?? :huh: