1979 850 Main jet suggestions

[resjudicata]

My '79 850GN is in good running shape. Valves done, carbs and intake o-rings, thorough carb cleaning and properly sealed airbox. Everything that we all tell folks to do. Factory carb jets and factory VM26SS carbs. Low speed the plugs look a good brownish but high speed they are white.

My bike has a V&H 4 into 1 with new baffle and now has a K&N factory replacement air filter. The bike runs great except at highway speed with the motor at about 5k if I open it wide it hesitates. I've tried raising the needles one spot from factory position. However, I get rich black smoke out the pipe on acceleration even when just revving in the driveway. So, I don't think I need to richen at all positions like raising the needles does. I now have the needles back to factory position. I'm planning on buying some larger mains. Since the mains seem to only handle wide open position then it appears that just upping the mains will solve my wide open hesitation without richening the mid-range. The factory 102.5 mains are in there now. I'm looking at the size list on Z-1 and the range I would expect to need are 105, 107.5 or 110.

Any suggestions or wisdom from guys who have modified the '79 850 VM carbs to run with a V&H combined with the K&N replacements filter? I'm just looking to see whether I need to get all these jets and start low or just grab the 110's.

Thanks,
Chris

[Big T]

Go to the 110s and see if that is too rich (2-3 sizes up from stock should be right)

[resjudicata]

Go to the 110s and see if that is too rich (2-3 sizes up from stock should be right)

That's kinda what I was thinking, 2-3 sizes. I keep reading where folks say that the V&H/K&N setup don't need to be rejetted but may run a little lean. I'm thinking I'm just a hair over the line. It still runs good at all except WTFO which most people never use. I try hard not to use it. But, sometimes it's too tempting.

Thanks,
Chris