Overheating and high idle

[4everFJ]

Hi,

New FJ1100 owner 

A couple of days ago I was riding in stop-n-go traffic for about 10-15 minutes and the FJ got extremely hot and started smoking badly from the engine (probably dirt/oil residue burning of).
I do realise that these big old air-cooled fours will get hot when idling too long and that they are constructed to be able to handle it.

However, as it got hot, the idle started to raise until it was idling at 2500 rpm, making it sound like the engine would explode when putting it in 1st gear...

After cooling down for an hour, it started up fine and idled normally at 1000 rpm.

Anyone who knows why the idle would go that high when getting hot? Under normal riding the idle stays at a stable 1000 rpm.

Thanks.

[Bones]

Sounds like you could have a vacuum leak somewhere. Mine did something similar one time when it got hot, idle was a bit fast and irregular, turned out the hose clamps on the intake rubbers between the carbs and engine were loose. With your engine running, spray some carb cleaner / wd40 around the rubbers, if idle increases you are sucking air somewhere.

[4everFJ]

Thanks, I will try that.