KZ 900 TRANSFORMATION CONT. SEGMENT # 1

It is most definitely suppose to be offset scooter. go ahead and fab it up without worry!

porchev914 wrote:

It is most definitely suppose to be offset scooter. go ahead and fab it up without worry!

x2

hey guys,

been a while, I know...

anyhow, I would like some input on the angle of my mono-shock. Is there an ideal I should be shooting for? Does it matter which way I have the gas chamber protrude? It's facing to the rear in these photos, can I switch that up?

your goal should be to copy the stock geometry from the bike the arm came off. this will ensure that the spring rate is correct.

Can you tell me more about "spring rate"? And another question, I'm not doubting what you say I'm just curious...In my mind how is the original set up on the original bike relevant since the bike I'm building is a compilation of different bikes (elements)? By copy the stock geometry do you mean the angle of the shock and the direction of the gas chamber as well?

Welcome back ScooterG. The angle of the shock is important because changing the angle changes the leverage of the linkage on the shock. The reason that you want to replicate the donor bike setup is that the linkage causes the shock to have a progressively rising spring rate as the suspension gets closer to bottoming out. This is the only shot you have at being able to use pre-defined spring rates to adjust the suspension to your bike. If you don't get it close, then it's going to be a lot of trial and error on your part since you will basically be the only person in the world with your exact suspension set-up.

Here's what I did. My donor was a 1995 GSXR 750. So I did the best I could to get the suspension mounted like it was on the original Suzuki frame. Easy enough for me since I had both bikes sitting side by side. After the suspension was actually mocked up on the KZ frame I went to Race Tech's website here: racetech.com/ChooseVehicle.aspx There I selected the 1995 GSXR 750. At the top of the page is a link to calculate spring rate and available springs. There you enter your weight, the bikes weight, and riding use (race/street.) Here's where I told the calculator that the GSXR 750 weighs 525lb(the weight of the KZ) and it spit out a spring rate for the front and rear springs along with a bunch of different spring part numbers with associated spring rates. So I ordered the springs based on their recommendations, and guess what? My bike actually handles pretty well. I don't have to worry about the suspension bottoming out which would have most likely happened since the KZ is about 100 lb heavier than the GSXR, and I'm no small fry either.

I don't think that the direction of the nitrogen reservoir is important, except for clearance issues. Hope that helps.

Hey thanks a ton Testa!!! That is exactly the kinda insight/info I was hoping for...I'll attempt to follow the path you described. First step: remember what donor bike(s) were hahah Seriously, THANK YOU!

This is where I was talking to the wall in another thread. Anyway...

Like what Test said about getting the geometry somewhat the same as the original ZX (or whatever). If I was in your shoes, without the ZX frame, etc, I would put the KZ frame up on a stand at ride height, attach the swingarm, wheel and shock to the s/a. Locate the top of the shock close to the angle it was originally, I really don't think it's that crucial, but it should be close. Remove the shock spring and temprarily attach the top shock mount with a bracket. With the spring removed, you can operate the rear suspension from fully compressed to full extention and check for clearances at the rear fender/frame, etc. If all is well, reinstall the spring and recheck ride height with FULL bike weight on it. if your engine isn't installed then find something to get the bike to weigh what it normally does. You can fine tune the ride height with custom tie-rods (dog bones).

More good tips from KK.

You can substitute sandbags for you engine as ballast. Drop a board in the bottom of the frame and pile them in there. The complete engine and trans with carbs weighs about 210 lbs.

Honestly if your swingarm is anything like mine, then it will have to be close in order to even get full travel in the rear. The cutout in my swingarm doesn't have much extra room. You want the angle of the shock close, but I don't think that a degree or two off stock will make too much difference. Just don't go trying to re-invent the wheel and lay the shock down or change the linkage. You are just introducing too many variables to an already complicated situation.