Issues with my '79 CB750K. Seems like getting too much fuel?? or not?

[cyclebuster]

well you know its in the carbs. take them back off again. look at the main jets and see what number is on the side of them. take the vacuum tops off, pull the slides up and see if the pins can jiggle in the slides. if not they may be shimmed up. take them apart and look. there is a method to check float heigth properly, as the weight of the floats depresses the pins and gives you a false measurement. there is a few things that can cause your troubles. when you take your carbs off keep them upright, and drain each one by the bottom plug into 4 clear glass cups and see if they are equal amounts of fuel.

 

[cyclebuster]

and yes the rubber plugs can be the issue, they are cheap.

 

[1979GreenMachine]

Question about the vacuum-piston needles. They dont have any wiggle to them. In fact when I removed them, there was a 'lock washer' between the needle and where the needle seats (bottom of the vacuum piston) - making the needle immobile. Are the needles supposed to have slight play to them for stock settings?

 

[cyclebuster]

yes they must move, the slides and needles even a fraction off center would hang up, they should jiggle, i am sure if you take them apart you may find some shimming.

 

[1979GreenMachine]

Ok. Just removed the 'shims' from the vacuum-piston needle, and now they have a slight jiggle. Started the bike and it still has the same problem. Engine ends up bogging down and dying, smells like alot of gas thru the exhaust. Guess I'll just wait till those rubber plugs come in.

 

[cyclebuster]

ok well the very next time you take those things off you MUST verify the jet sizes. you can take them off and see if you can blow into the passage the plugs use. btw my last dohc was strong as an ox. It just has the "too new" look for me.

 

[1979GreenMachine]

Ok, Just got the rubber plugs installed on the bike today. I think that was the problem. Seems to be running perfectly now. No 'flooding out' or smoke out the exhaust. I did verify the sizes of the jets while I had it apart, main and slow are 102 and 68 (stock sizes). Anyways, Thanks for the tips and advice!

 

[dirtdigger]

Good to hear it, glad to help.