High Idle Issue
 

Hey guys-

I just recently picked up a 1999 F4 with about 68,000 km. It was running quite mint till the other day when I ran out of gas due to a faulty 'low fuel' light. My cell phone was dead, so I asked a resident in the area if I could borrow some fuel. Feeling quite worried about using random lawn mower petrol in my bike, I held my breath, and took the last resort. I managed to get myself to a near by gas station to fill up.

After I fill up with proper premium gas. I notice my idle is roughly in the 2,000RPM range. No change in performance, just a higher idle now. I try and unwind the idle screw but still no change. I inspect my intake for a possible vacuum leaks but no dice. The bike was idling fine before I ran out of gas. Any ideas?

I wonder if some crud from the bottom of your tank somehow got into one of carbs when you ran it dry. I've had the exact thing happen before. A good flushing of the carbs may be in order.

Tried putting some carb cleaner through, had a low idle for a minute. Then went right back up. =/

i doubt that will do i. you will probably need to pull them, remove the bowls and go through it throughly

I think I've got the problem nailed down to a vacuum issue. I disconnected the vacuum tubes from the air cleaner housing and now it's idling at 1,200 rpm. Maybe my carbs need to be re-synced? When I re-connect the tubes the idle goes back up.

assuming they were in sync to begin with, you shouldn't need to resync them.
If your valves get out of whack or you fully separate your carb rail, then you have to resync.
as long as you didn't touch the sync screws, that shouldn't be your issue.

Thanks for the info @hamlin6. With two of the four vacuum tubes from the air cleaner housing disconnected it is idling normally, and performers up to spec. Very strange situation lol.

Great news. Glad to hear you got it sorted out and that it wasn't a big issue. Be safe.