Topic: cb400 jetting

[mazdamx640]

i have a set of carbs off a cb350 that i am going to have cleaned and rejetted for my 76 cb400 so i bought a rebuild kit for a cb400. after som research on this site i found out that the cb400's were jetted too lean so what jets should i use for stock air box and exhaust ? the rebuild kit came with a #75 main and a #40 slow

[Gordon]

after som research on this site i found out that the cb400's were jetted too lean so what jets should i use for stock air box and exhaust ?

Who said that?  My 400F ran just fine with the stock air box, stock pipes and stock jets. 

[supersports400]

Hi,

to lean or not to lean, it depends where you live and what the atmospheric conditions are.
I live in the Netherlands, low country, moister and somewhat moderate temperatures.

On the dyno it was showing clearly a lean mixture in standard trim between 6000 to 8000 rpm, so I went from 75 to 78.
It was a good improvement, not to rich not to lean, just good.

Jensen

[Deltarider]

That's why on page 17 of the genuine parts list for the CB400 you'll find no less than three main jets denoted: #72, #75(STD) and #78.
(Hi Jensen, you live close to where I was born.)

[dansvs]

You should start with the stock sizes and go from there. You need to test all throttle ranges for correct jet sizes. You can get jets at JETSRUS.com or other sources. Don't skip the needle jets or jet needles. A flat midrange could be needle problems. As stated earlier, you will set richer in cold weather and leaner in hot. Here is one link to tuning. There are others on this website.
My name is Dan but this link is not mine.

http://www.dansmc.com/carbs2.htm