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Was at a dealer today and was talking about all the stuff we talk about on here and he showed me book that had updates. The carb heaters should be off if colder than 30. If warmer than 30 then turn them on. It sounds backwards because the potential for freezing has to do with humidity. When it's colder than 30, there is little humidity and is less likely to freeze. Over 30 the humidity is high and could freeze. I read it right out of his book that was published for DOO techs.
 

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Phil in the NEK
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Then why does the owners manual (written by Ski Doo I would assume) say the exact opposite?

Terer is actually a CAUTION in mine tha says not to have it on above 41F.

Just doen't make any sense to me
 

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Your right on not making much sense, but that's what it says. It was printed in plain english in the updated book he had.
 

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Only problem i found last year running them on above 30 degrees is after a long run with a good heat soaked motor the sled would not start. The hot coolent " boiled" the gas out of the carb bowls. I leave mine off at all times never had a problem with icing ridden anywhere form -40 to +50 degrees
 

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So how hot do you think that coolant was to boil the fuel out of the bowls? Just imagine if your sled had the beavertail removed!!!
 

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TT,

I ran my own copy of the "elimnation bars" the last half of the season and belive it not the fuel boiled with or without the tail. I was the gunine pig to try the bars out of our group of 6 rev's. I think what u did is the way to go tho even tho i did not hav any trouble with overheating
 

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Rev man thats my point these sleds run hot even with the beavertail, the MPEM starts pulling timing 1 degree at a time to prevent engine damage, long before the temp light comes on. I had the it read to me over the phone directly out of the bombardier service info late last winter, gave temps and increments of timing reduction.. I wish I could remember the specs. Doo went to the larger capacity heat exchanger for a reason. Just cause your temp light is not on doesnt mean its not too hot to hamper performance.
 

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I have had 3 yamahas with the carbs heters (1 600 and 2 700s)
and I nvere had any trouble starting them with the heaters always
on (sometimes above 45 degrese) and never had a problem.
I will leve mine on i don't want my carb frezing and sticking (it happed
to my buddies formula Z not fun) but to each his own
 

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TT,

I did not know about the timing thing thanks for the info guess i will be calling PLP in the morning
 

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Please post info when you find out!!
 

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REV-I-DOO, you have the same info that I have. And I agree with the logic behind it. I spoke to someone regarding when to turn them on and such....the only time he turned them on was in 28 to 32deg weather and he noticed his sled running funny so on they went and withing a minute everything was fine. I'll leave mine off until I notice something funny. Hopefully the residual heat in the coolant will warm up the carbs to stop the freezing when the sled is off.
 

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The direction to use the heaters in temps above freezing does make sense. General aviation aircraft have carb heaters for exactly this reason. The incoming air temperature drops as the air speeds up through the carb, especially at full throttle. If the air is humid this can cause ice to build up in the venturi and choke off the flow. Airplanes use carb heat for takeoff and landing just to be sure they'll have a consistent running engine.

In flight they'll use the carb heat as needed. It can take a couple of minutes to melt the ice and it may really run like crap while it's melting it but then it clears out.

Since snowmobiles are ground-based machines it doesn't seem like a necessary feature. I'm going to keep mine off unless I'm playing in powder all day or something like that. A mountain rider might really appreciate this feature though. I wonder what caused Doo to put this feature on all the Revs?

Jon
'03 Rev Sport 600
 

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The small airplane scenario is correct. Personally I leave my carb heat on at all times. Any snow dust or humidity coming through your carbs can freeze and your throttle can actually get froze open. Ever put a air gun to your hand on a hot day. The air cools coming through the venturi. Never had a problem while leaving mine on. Yamaha runs heated carbs too...hmmm must be a reason huh?

Never hurts to run some Isopropylene in your gas either to dry out the water caused by condensation.
 

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734 Power
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REV BARON, get ready for some crappy perfomance, been running doos for a long time, never had the carb heat on once, its worthless if you ask me
 

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My sled won't run with carb heaters on when its over 35F...

In the warm weather I was having problems keeping the 800x running it actually ran like the carb had ice in it, and it was almost impossible to start... then when I turned the heater off it started and ran perfectly ???
 

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I'm very happy DOO put them on! When we ride it's nose to tail, you have to trust your buddy, weakest forward and strongest to the back. A self handicapping method, when doing this one gets an extreme amount of snow dust, Ive gotten enough to stick my steering & throttle, as for the rest of winter I had to duct tape my vents in my hood to keep my steering from locking up. (Too much snow injestion.) Ya I know, give your self some room. Anyway, they are nice to have in conditions like this.
 
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