Hi guys, just lately my rvfs revs and idle have been all over the place, started ok and ran alright for a little while then revs would just drop off at idle and the thing would die. I stripped it down and sent the carbs off to be serviced. The guy found a broken primary jet that was jammed in the carb and said the whole lot looked very tired. Anyway he has fixed and cleaned and replaced it all and said he has left them at standard settings. I got them back just fitted them to the bike and apart from it reving smoothly its still all over the place, the idle will sit at 4 then jump down to 2, sit there for a while then bounce a bit and then eventually die, tried playing with the idle screw but as soon as u lower it it dies, am i right in thinking i just need to get the carbs balanced and set up right now they are back on the bike or do you think im looking in the wrong place for the solution

If you ignore the idle issue, does the engine run ok through the mid range and above when ridden normally and no power loss at high revs/speed.

more information needed as magg has asked.

just a few things it could be (among many)

air leak aroud carbs / inlet rubbers.

vaccum leak from broken vaccum tap line / missing balance screw

electrical issues.

carbs way out of balance / valves way out of spec

I havent ridden it since putting carbs back on but seems to rev up in neutral fine

Another issue could be a fuel flow problem which would be easier to identify if there were issues when riding, having said that, does it idle better with the fuel cap open. Also is there good fuel flow from the tap when a vacuum is applied. You may need to check that the pilot screws are set correctly.