i just bought an 07 summit 800X and it has a carb heater, i dont have an owners manual so could someone please inform me when i would turn on the heaters???
carb heater
- Thread starter shaned
- Start date
Almost never....not unless it hits about -20 and you have icing problems.
Carbs are actually less prone to icing in very cold weather because of the low humidity associated with very cold temps, and the fact that the water vapor in the air is already frozen and just passes through without sticking. The highest probability of carb icing occurs just above freezing, on days with high humidity when running long periods at partial throttle, like a trail run. The unfrozen water vapor in the air is cooled in the carb venturi and the vapor begins freezing to the carb internals. If not addressed, performance can drop as the ice builds and less air can get through the carbs, causing the engine to run rich.
So, if it's a good idea to keep the carbs de-iced, why not use carb heat all the time? Well, it's not a good idea to run with the carb heat when it's not necessary because as the incoming air is heated, the engine will create less power. Also, when you are running carb heat it may be a good idea to turn it off for a couple minutes before shutting the sled down for a while (like for a long trail stop for lunch). If you just shut it off, the residual heat can evaporate the fuel in the carbs and make it hard to start when you get ready to leave.
Oh. One more thing. If your carbs are already icing and you turn on the heat, you may notice poor engine performance for a couple of minutes. Don't panic. This is actually a sure sign that carb heat is necessary. As the ice melts, a small amount of water is ingested into the motor which can cause poor performance until all the ice is eliminated. Shouldn't take more than a couple of minutes to clear and you'll be back to riding circles around your buddies that don't have carb heat.
So, if it's a good idea to keep the carbs de-iced, why not use carb heat all the time? Well, it's not a good idea to run with the carb heat when it's not necessary because as the incoming air is heated, the engine will create less power. Also, when you are running carb heat it may be a good idea to turn it off for a couple minutes before shutting the sled down for a while (like for a long trail stop for lunch). If you just shut it off, the residual heat can evaporate the fuel in the carbs and make it hard to start when you get ready to leave.
Oh. One more thing. If your carbs are already icing and you turn on the heat, you may notice poor engine performance for a couple of minutes. Don't panic. This is actually a sure sign that carb heat is necessary. As the ice melts, a small amount of water is ingested into the motor which can cause poor performance until all the ice is eliminated. Shouldn't take more than a couple of minutes to clear and you'll be back to riding circles around your buddies that don't have carb heat.
A
AMSOILR
Well-known member
I found out the hard way on my new 03 800 Rev. For about the first 3 rides I could not start my new sled after we stopped and sat for any length of time. It would flood every time. I finally checked into the carburetion and found the carb heater valve. I shut it off and have never had it on since. My dealer never metioned it. I've had an 06 and a 08 XP with it on as well. I quess there are occasions when it could be used, but I have not seen it.
Can you please explain why you think sub-zero temps are the best time to use carb heat?
Is this the same for like the RT1000 motor w/o the carbs? Cuz they still have coolant running through the Throttle Bodies but there is no shut off valve.
Depends on the region...you being in AK are cold, here in Wa we may start our ride at or above freezing and ride to elevation where it is much colder. They are rarely used around here. Doesn't Doo advertise the carb heaters for extreme cold use?
M
mcgyver
ACCOUNT CLOSED
I can't explain why, but the two rides where I needed to use the heaters were both well below zero unloads......
One was -19 and the sleds all ran like crap till we turned them on....no problems after that......
the other ride was a little warmer at -5..... IDK, because we have ridden other times at -5 with no problems... it had to have something to do with the humidity even though I would agree, at that temp relative humidity usually goes down.
these are 07 XRS machines in SE Idaho
In my area carb heaters are only worth having in -20c or colder.
I use it often.
I don't use them very often but would not take them off because the day that you need them you'll be glad to have them. I've been out at -20 c and had a bunch of humid air move in and after that the carbs started to freze up. I live in northern
Alberta and sometimes its -45 c and thick fog up here I don't ride when it's that cold but if I had to I would turn on the heat.
Alberta and sometimes its -45 c and thick fog up here I don't ride when it's that cold but if I had to I would turn on the heat.
Page 64 of the 2008 REV XP series Operator's Guide says the following:
The heated carburetor valve should be closed except:
-When riding between -5C and 5C (23F and 41F) in a high relative humidity.
-When riding in deep powder snow.
-When following another snowmobile in high snow conditions.
So, I guess BRP agrees with me. But, it's not like BRP hasn't been wrong before. I know I have.
Sure. It's a combination of temperature and humidity that causes icing. And given the right humidity, icing can occur in a wide range of temperatures. But, the most common temperatures at which icing occurs is near freezing. And, since the OP asked for a recommendation on when he should use carb heat, telling him about the most common conditions that produce icing seemed like good advice. Take it for what it's worth.
