Hi All,
I have an 89 FJ1200 that has all pollution restrictions removed, valves have been adjusted with new shims, new carbs, new manifolds, new Dyna-tech ignition, new Dyna-tech coils and wires, new plugs, new fuel pump and hoses. Bike runs great, pulls strong through all gears but when it gets hot it idols up, I adjust it back down and next stop its back up again. I have checked the cables, all good. This has me baffled and was wondering if anyone has had the same problem. Most of what I have read on this is the carbs but mine are brand new and were adjusted by the manufacturer. Something I have noticed but not a lot, when I stop and the idol is high once in a while carb 4 will pop out the air cleaner but not always. Motor has good compression on all cylinders and there are no air leaks.
Thanks for any feedback
Pete
When a bike gets a hot fast idle (assuming your linkage is correct and your choke is fully disengaged) it means that your idle air/fuel screws (top of carbs) are too rich.
The rich mixture plays fine on a cold bike....but when it heats up, the idle races.
What are they currently set at? (How many turns out from the lightly seated)
Try turning them in 1/2 turn and see if that helps.
What is your carb jetting? Pilots, needle position and mains.
Sounds like you have individual air filters. Very common for the #1 or #4 to fall off.
Throw them away. Get some UniPods from RPM. Problem solved and better filters to boot.
I had that problem a long while back. A carb sync cleared it up.
Good point Chris....I assumed carb's are always sync'ed, but that may not be the case.
In fine tuning your carbs, carb synchronization and valve adjustment should always be first on the list.
Then main jets for 3/4-WFO best response.
Then needle clip position for 1/4 to 3/4 throttle best roll on response.
Then pilot jets for idle/low speed.
Lastly Pilot air/fuel screws for final adjustment.
If you don't follow this order^^, you will go crazy.
Depending on jetting and altitude, many folks start with the pilot air/fuel screws at 2.5 to 3 turns out (from lightly seated) and go from there.
I bet it is an air/vacuum leak somewhere.
In my experience, when the idle races up when hot, it has always been an air leak.
"Then main jets for 3/4-WFO best response.
Then needle clip position for 1/4 to 3/4 throttle best roll on response.
Then pilot jets for idle/low speed.
Lastly Pilot air/fuel screws for final adjustment.
If you don't follow this order^^, you will go crazy."
these are words of wisdom!
I hear fancy wording all day at work.and these tchs couldn't gap a spark plug.js