Is the motor stock, pipes and pods excepted?
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And yet another dumb carb question
- Thread starter Mickster
- Start date
It doesn't get much simpler the Mikunin VM carbs, a very slight performance increase, so they say. Simple, efficient, easy to setup, easy to tune, minimum parts, cheap, parts, and they are Mikunis.
The only problem might be clearance for the taps.
The only problem might be clearance for the taps.
Whatever you want to do to the needle, you do the opposite to the clip to achieve it. To raise the needle, you lower the clip and to lower the needle, you raise the clip. The '78-'79 carb set has the largest mains and smallest needle jets of any of the BS38s. The main jet size directly influences what size needle jet can be used. But even with it's small Z-2 needle jet, the upper midrange in this carb set is still on the verge of being too rich. That means any increase in main jet size, even one, will push it over the edge and cause stumbling under heavy throttle applications unless you lean the needles a step.
So, richening your needle setting by moving it back to the #3 slot probably isn't going to work, especially with you being 3 sizes up on the mains. Your issue seems to be in the lower range anyway, in the idle to midrange transition area. While leaning the needle is needed to fix the upper midrange stumbles brought on by larger mains, it's a double edged sword because it also leans that lower idle to midrange transition area. So I'd try the 32.5 pilot.
So, richening your needle setting by moving it back to the #3 slot probably isn't going to work, especially with you being 3 sizes up on the mains. Your issue seems to be in the lower range anyway, in the idle to midrange transition area. While leaning the needle is needed to fix the upper midrange stumbles brought on by larger mains, it's a double edged sword because it also leans that lower idle to midrange transition area. So I'd try the 32.5 pilot.
Mickster
XS650 Enthusiast
Well, I finally got around to yanking the carbs. Put in new fuel lines and filter, gave the carbs a good cleaning and relocated the needle from slot number 2 (from the top as Jim suggested) to slot number 3 from the top.
Took it for a 10 mile test ride today with low throttle to medium throttle to wide open bursts. The bike transitions pretty smoothly through the throttle positions. Next is to try some proper air filters and maybe it'll smooth out some more.
Soon as the motor cools down I'll yank the plugs and take a look see for rich running. The 32.5 pilot is not off the table.
Thanks for all the input.
Took it for a 10 mile test ride today with low throttle to medium throttle to wide open bursts. The bike transitions pretty smoothly through the throttle positions. Next is to try some proper air filters and maybe it'll smooth out some more.
Soon as the motor cools down I'll yank the plugs and take a look see for rich running. The 32.5 pilot is not off the table.
Thanks for all the input.
