Topic: Reading the Manual - jet size notation

[ron.cieri.313]

Hi all, I am going back to a stock air box on my '76 CB750K.  I think they had #105's on it prior to my rejetting to compensate for the &()&**&&%^%&^%(^&(*(_^^%$$%^ air pods

found this notation in the manual but don't understand it

Main jet    #120 (#105, K3)

....does that mean stock main jet size is #120's unless i have a K3?...which I don't

thx!...ron

[laser145]

I don't know the answer...but I also have a K6 and am doing the same thing...so I'm interested in the answer

[Gordon]

K6 should be a 105. 

[333]

Parts diagram says #105

[ekpent]

If your running the 4-2 exhaust I saw pictured early on I would probably shoot for the 110 main,or have some available for comparison.

[laser145]

So if I'm running a MAC 4-1...still 105 Main Jet?

Cheers

[Doctor_D]

Depends.

How's it running? What do the plugs look like? Do you have good power across the range of throttle openings?

[Gears]

I'm interested in this too. I'm rebuilding a set of carbs off a K5.

My manual lists the mains as being 120's(in the main section. It didn't mention anything about jet sizes in the K5 supplement elsection) but the keyster rebuild kit I purchased came with 110's.  And the main jets I pulled weren't very well marked.  I can make out a 1, then there's a space, a 5 and a little k/star symbol. I've been working under the assumption that these are either 105 or 115's.

So you can see I'm a bit confused by all this too.

Not to mention trying figure out what I should run if I go with pods and Carpy's 4-1 exhaust .   

[xenoscr]

I have a 1975 CB750K5. I've just gone back to the stock airbox from pods. I had #42 idle, one noch lower on the needle, and 115 mains. The link in the FAQ list the following:

Code: [Select]

Year    Model  Casting #    Type Float Main Slow JN Screw
69-76 CB750K B750A & 7A   1    26    120  40 3  1
               657A         1    26    110  40   4  1
               657B & 086A  1    26    105  40   4  1
Source: http://www.motorcycleproject.com/motorcycle/text/specs.html

So now I have #40 idle, notch 4, and stuck with the 115s since I went with a K&N filter. I first tried the jetting I had for the pods. Way to rich, black smoke and everything out the tailpipes, damn.... had to rejet. Runs fine. It was past my bedtime when I finished rejetting to stock so I've yet to do a plug chop. I'm not getting black smoke from though... so I'm at least not super rich.

XeNoSCR