Carb icing in motorcycles
Carb icing normally happens at temps of +4 to 0 degrees, it can happen at higher temps but normally it will need fog or mist to happen in the +8 to +4 range.
Once its actually freezing out the problem tends to go away as the moisture entering the airbox freezes and goes to the bottom of the air-box instead of entering the carbs.
There's some really good vids of the process happening on a yamaha vmax owned by Johnpclynch .
Symptoms are typically rough running which gradually gets worse until you have to stop,then bike wont start or struggles to start but if left for 5 mins its back to normal, goes great again but 5 mins or so on an open road and it starts loosing speed gradually again.
People generally suspect dirt in carbs or a dodgy coil breaking down under heat.
This inquiry is very typical of inquiries about the subject in the workshop.
Hi
Having a bit of trouble, seems when I'm traveling steadily at 60 to 70 after a few mins the bike would just suddenly out of nowhere drop down to 55-45 and there would be no encouraging it to pick up speed again it just keeps going down gradually so I'd drop her down to forth still no go, so I pull into the hard shoulder and pull in the clutch and then it will just die, and is a cunt to get going again and it's never usually hard to start.. Happened to me about four times on Friday.
The weird thing is I could drive around for hours on roads that I have to keep altering my speed and it wouldn't happen but on a straight line for five ten minutes it will happen without fail..
Any ideas to what the problem is? Minor/Major?
Many manufacturers tried various carb mods, some better than others but none were perfect.
The Kawasakis suffered badly from it thus they modded them carbs by feeding warm coolant to the underside of the float bowls but the skinny pipes and filter often stop the flow so it lets the bike down.
Suzukis tried the stupid electrical carb heating method and i doubt it ever worked right.
One thing that definitely does work is silkolene pro fst. The stuffs great and if you suspect carb icing get some straight away.
Hope that helps.
Tara Rose Poleon