KZ750 Twin jetting for Albuquerque or Colorado with 2 into 2 pipe?

Hi folks,

I've got a 1979 KZ750B-4 that I purchased as a non running project, last September. I've just gotten to the point where I've been able to start the bike.

The previous owner had the stock 45 pilot jet, 125 main jet, and needle jet setting at the 3rd position, with a 2 into 1 exhaust. The spark plugs I removed from the bike from the last time he rode it looked really good, with a nice, milk chocolate brown color.

I've removed the 2 into 1 exhaust, and installed a MAC 2 into 2 setup with no crossover, and have kept stock jetting (45 pilot, 125 main, 3 clip position on the needle jet).
I am using the stock airbox with a clean and oiled K&N filter. There are no air/vacuum leaks.

Upon first start, (no riding, yet), it appears that the bike is running a bit lean. Air/fuel idle adjust screw doesn't do anything within a full turn in or out from the 1 1/2 turn setting as listed in the manual. I only see a difference if I turn it all the way in. That points me in the direction pilot jet is too small.

Also, the spark plugs are white after running.

I'm wondering if there is anyone riding the same bike with the same setup in the Albuquerque or Colorado area. We are a mile up and that will affect jetting. I'm looking for some recommendations as to jet sizes.

Thank you.

Hey Mr. Kon!

I love your YouTube videos -- very glad to have found you on here as well.

I also have a KZ750B-4 and I live in Colorado!

The bike was completely dismembered when I bought it and I'm in the process of reassembly/reanimation. I haven't started it yet (putting the engine back in the frame this weekend if all goes well), so I'm not sure if there will be any running issues. I would love to know what you ended up with in terms of jetting & needle position. Judging by your videos, you seem to have your bike dialed in very well.

As it sits, I have 135 main, 45 slow/pilot, and the is needle smack dab in the middle (3 clip position). My exhaust is stock for now, but I may change that in the future as the silencers are pretty close to rotting through. I haven't found many bolt on options for a replacement, but maybe I'm just looking in the wrong spots.

Again, thanks for all of your wonderful content on YouTube!

-Meat

I've some experience with 750 Twins.

I'll get into my notes to see what I did for jetting.
Bill