[jkv45]

Originally Posted by notunderweight

Hey all - just figured I'd post a brief update, it's been a while.
I've made some progress! Finding time to work on the bike with the wildfires and everything has been kinda tricky, but i made it out there yesterday and today. Some highlights:
I got the right diameter vacuum hose for the petcock, and that helped. I think the old hose was leaking or something; the last owner confirmed it's been an issue for him in the past. Anyway, that helped a lot (if not quite enough for me to be comfortable with it on public roads).
@.Danno, I tried to get a vacuum gage a couple times this week, but neither of the auto parts stores I frequent had them as loaners. I went ahead and just ordered one online, itll be here soon. In the meantime, I noticed that, while both are jerky and stuttery above like 6k, switching the petcock to reserve actually makes a difference in power. I think I'm gonna drain the tank and clean the petcock filter this weekend.
(SNIP)

That would suggest the petcock needs to be cleaned, rebuilt, or replaced.

The screens on the normal pickup inside the tank may be partially plugged if it runs differently on Reserve.