Topic: Jetting suggestions - Did I do my math right??

[KB02]

1978 CB750K
Bored out to 850
Head ported (Mike Riech Stage II)
Webcam 41a
Opened up, Custom, 4 into 4 exhaust
Individual Pod filters
The stock (as far as I know) jets that I pulled out of the carbs were 110's.

Being that the engine is now 15% larger, my jets should increase accordingly, right? (15% puts it at 126.5 - lets say 125's)
With the open exhaust, I should bump up one more size, right? (127.5's)
With the air filters, that could increase size once again. (130's)
Realizing that with everything put together, I could easily over do what needs to be done, lets pull it back a size. (127.5's)

So, would the engine tuners agree that 127.5 main jets would be a good STARTING POINT. I realize that I will need to do plug chops and plug reading and seat-of-the-pants tuning to find the RIGHT jets, but what do you all think?

[Simpson]

Good luck making calculations in your head. It's a good place to start, but with my limited experience you are often in for surprises. If I had to make a guess I'd say 130.

[mystic_1]

Don't sweat the starting point so much since you know you'll have to rejet a number of times to get it right.  You could almost throw a dart to pick your starting point.  From there follow the readings.

mystic_1

[KB02]

Well, the local Honda shop didn't have any 127.5's, so I got 130's instead. We'll go from there.

[mlinder]

Engine size doesn't affect jetting, really. At least, not linearly to increase in size.

Remember, the jets meter out fuel according to vacuum. Vacuum is created by the pistons moving down and pulling air through a restriction, in this case, carb bodies and filtration system. All other things being equal, the increase in vacuum from increase from displacement should be matched by the same jet, assuming you don't reach a flow restriction singularity.
With work by Mike, the combustion chamber is probably more efficient anyway, meaning a closer to stoich mix will probably run better than before, meaning you can't use stock jetting as a reference point anyway.
I'd start with 130's, in any case, due to your pods.

/edit just read you got 130's