Carbs and cams

Scoring a really cool 75-1/2 KZ900 today.Bike is completely O.E. with 14,500 miles. Gonna do some mods,but keep it modest. Got a 6" out swingarm, getting a sidewinder and gonna go with cams and carbs. My question is, How big on the cams and carbs??? gonna be mostly street and a stock engine(for now), may build something bigger later using a different block so as to keep all the o.e. parts for later restoration or sale. .385" and 30mm???? :side:

.365 and a set of 29s would work better on stock motor

Whaddya think as far as e.t.? low 12??

That depends entirely on the track location and rider.
Carefull with that sidewinder pipe,many of them wont clear a stock unraked front end and could jam the wheel between pipes in a corner or hard braking

That, I did not know...hmmmmmm. This is ok though, as i was waiting until it's too cold to ride before I perform any modifications. I know that it needs to be raked anyway to correct the "high speed wobble" they are notorious for because of the stance. Now, does anybody make offset cups for these? They are very popular in the Sportster world.

The only time I ever experianced any kind of high speed wobble was when I let somebody rebuild a front end that didnt do things right ,which led to a tank slapper but I managed to get it back under control and made it back home and rebuilt the front end myself.
Other than that Ive never had a front end issue with 30 plus years of pushing these things harder than most anyway.

One other thing you'll want to add to this list in your build if truly other than basic clean stock performance.... Head valve job and P&P... If it don't flow, she won't go...

Translation: Need the air intake for all the combinations to work for desired performance.
Contact Larry C, he'll be able to explain it fully on what combination (Valve sizes, porting. cams etc...) would work better for your desired results.

OMR

wireman wrote: That depends entirely on the track location and rider.
Carefull with that sidewinder pipe,many of them wont clear a stock unraked front end and could jam the wheel between pipes in a corner or hard braking

Will also mess with the rear brake pedal. Most time have to mod it.....also might need a rear mount fabed for the megahone.

I went 12.19 @108.95 39 years ago on my new 73 Z1 with nothing but a pipe on it and I was a fat kid then.

Yea, I was reading up on the specs of the Z1 and they claimed a 12.0 E.T. stock. When I was looking into this bike, I thought it was a plain Jane KZ900 of the 1975 vintage, however when I got the title from the previous owner handed to me I promptly noticed that it was a 76, then noticed the Z1F in the first three characters.....woo-hoo!.....SCORE!!!!....I "almost" felt guilty..... It's pretty quick. was running lean from restrictive fuel filters and smokes a bit with some blowby spilling oil from the ccv. I suspect that there may be a damaged piston. It only has 14,800 miles on it.

Does anybody play with the timing on these engines much? Where is a good setting? Are they conservative with the ignition lead from the factory?

You can take the exact same bike and run it in nebraska/colorado and texas with same rider and Ill bet you $100.00 you get 3 totally differant times on it.
Hell you can run your bike at topeka kansas then run it up to eddyville iowa and run it the same day and not run the same time!
Anybody whos ever spent any amount of time racing whether its a bike/boat/car or a turtle will tell you the same thing. :laugh: