Rough running at idle when hot

dcarver · Jul 10, 2006

Noticed this three times now. After sitting in the hot sun after previously being ridden, my 06 starts 'hard', has a noticeable rough idle and sounds like misfiring cylinders under say 2.3k rpm. Once it gets over approx 2.5k rpm it goes away and all is good.

When I say hot ambient temperature, i'm talking about the amb temp gauge reading 115 F at start time.

Anyone else noticed this and or have ideas to the cause?

Rogue · Jul 12, 2006

Did you fill the tank shortly before parking it? I had this problem with my Connie (CA bike). I would fill the tank on the way home from work (Short distance) and leave it in the sun the next day and it would run like crap or not run. I finally determined that the fuel in the tank was expanding in the heat and filling the charcol canister! It would then run way to rich untill the fuel/vapors were somewhat cleared out.

dcarver · Jul 12, 2006

Rogue said:
Did you fill the tank shortly before parking it? I had this problem with my Connie (CA bike). I would fill the tank on the way home from work (Short distance) and leave it in the sun the next day and it would run like crap or not run. I finally determined that the fuel in the tank was expanding in the heat and filling the charcol canister! It would then run way to rich untill the fuel/vapors were somewhat cleared out.

No, I've not filled the tank then sat it in the sun. It's occurred with 1/2 tank and less. It seems like the FI mapping just goes bonkers down low. I even have to give it ~1/8 throttle to get it to start...

radman · Jul 12, 2006

Check to be sure the tank vent line is clear and functioning. This has caused many odd behaviours, not unlike what you are experiencing.

evil_henchman · Jul 12, 2006

I think this has been covered on pre '06 models on another forum. It appears to be common on California models and has something to do with the charcoal canister as Rogue mentioned. My '05 does it and it doesn't matter how full the tank is, all it needs is a hot day and a hot restart. I just rev it under load and it clears right up.

I have de-kalifornicated other bikes but this problem with the FJR doesn't appear to be one that will leave you stranded. Unlike the California model KLR650 which most definately will.

At worst it's an annoyance and can be embarassing.