My 88 ran like a sewing machine until it sat for a month. The bike fluctuates rpms at idle and doesn't want to go above 4000 when riding. The bike was missing the fuel pump when I bought it and read that you could gravity feed the carbs so that's what I did. I put close to 1000 miles on the bike the way it sits right now with no problem. I have ran at least 4 gallons of gas and some seafoam through it since this problem started. I just don't understand how it could go from so good to so bad in a month. Any help would be greatly appreciated.

 

Maybe something has blocked your idle jets.
Not wanting to go above 4000 revs means probably main jets are blocked too.
I'd pull the carbs off, strip, clean reassemble and synchro them........

I'd also look at your air cleaner and maybe replace it- possibly while sitting something got in there and ended up in your carbs. It has happened before................

It is also possible that minute particles of rust from your tank have partially blocked your petcock filter and maybe gone into the fuel lines.

 

One more thing that Shadow didn't mention, the breather tube to the tank could be plugged. What happens if you try to hake it up over 4k rpm with the fuel cap off?

That problem has surfaced here a few times.

 

Thanks for the replies. I rode it today with seafoam in the gas and it cleared it out. Must have just been clogged jets.