Topic: 78 CB750 Boring the pilot jet - whats the non-bored equivalent size?

[lucky]

The slide valve affects carburetion between 1/8 thru 1/2 throttle. It especially affects it between 1/8 and 1/4 and has a lesser affect up to 1/2The larger the cut away the leaner off idle. A slide marked 3 is a 3mm high cut out. And it's affect is mostly when slide is moving up.

Thank you so much for that information Anders288!

[crazypj]

At least someone is trying to keep on topic 
Measure the ctual cutaway on slide
 On smaller carbs it does appear to be in mm, but, I have measured some where it doesn't seem to follow any measurement? (eg,  #3 cutaway was 5mm high)
 Maybe 'proprietory' for a specific application?

[timdhawk]

Well, I tried my Mac muffler instead of the diffuser and I'd made to much of a difference... I went from 2 1/2-3 turns out down to about 1 turn out and I'm still sputtering rich with that. I had no idea a muffler would make that much of a difference on an NA motor.

[lucky]

I posted a drill size versus jet size chart on this site at one time but can't find it now

All you have to do is go to Google and type in inches=mm and you will get a conversion chart. simple.

[lucky]

Sorry, no
It's a way to change mixture and stay in EPA spec
Correct float level is ALWAYS the number given, the +/- is for low/mid range adjustments if there is a running problem
Lower level on float raises level of fuel and richens transition and mid-range
The total fuel flow at/near max rpm stays the same as that is limited by the jet sizes

Thanks crazyPJ that could be very helpful with the 1978 CB750  tuning.
I am convinced that the 1978 CB750 could benefit from a needle position being made richer.

I actually tried it when I had stacks on it and it really responded very well.