Not sure exactly where vacuum drops to nothin',... Probably 3/4 throttle or so,... it might come up a little once your speed matches the throttle position.  But I'm mostly just guessin'...

Here's a way to test the main....
To test the main, accelerate from 30 or 40 mph, in 4th or 5th gear at full throttle for several seconds, then reduce throttle by about 1/8,...if power increases for a second, you are lean on the main jet.  Go up one jet size and test again.

PS,.. here's another jet diameter link...
http://suzuki.theatvchannel.com/invision/index.php?showtopic=72965&st=0&gopid...

Here's an interesting throttle position chart I found... notice the overlap...  I believe it's for a Keihin, but the principle is the same...

Serowbot wrote on 08/01/09 at 10:34:35:

I've tried that with 145, 152.5, and 155. Never noticed a change in power.

So far I've ridden with (Dyna exhaust):
55 pilot (1 turn out) / full spacer / 155 main
55 pilot (1 turn out) / no spacer / 152.5 main
55 pilot (1 turn out) / half spacer / 152.5 main
55 pilot (7/8 turn out) / half spacer / 145 main

Full spacer left me a weird surging condition 1/8 to 1/4 throttle.
No spacer fixed that, but killed my mpg.
Half spacer leaves me with a weird surging condition 1/8 to 1/4 throttle, but only when the engine is cold.

I just finished installing a 150, so I'll let you know how that goes.

Update:
Well, I guess I never hit "Post". It's now a few hours later and I just got back from a test ride with:
55 pilot (1 turn out) / half spacer / 150 main

There's a difference between 3/4 throttle and WOT now. Not a huge one, but I can feel it.

I guess the next step is to retest 152.5?

-D. Dwarf

DrunkenDwarf wrote on 08/01/09 at 13:41:58:

Now that I'm thinking more about it. I wonder if my pilot is a tad lean? I am getting backfires on throttle close...

-D. Dwarf