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snowmobile help please


jim wheely's Avatar
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01-04-04, 07:43 AM   #1  
jim wheely
snowmobile help please

i have a yamaha 440 circa 1979. it starts great and idles fine but under load it does not rev up. if i choke it i can build rpms enough to start driving but they will drop once it is going. so i let go of the choke and it does speed up but it does not maintain rpms. it revs up then drops and then keeps repeating this. but the rpms never build up quickly you have to give it alot of time to rev up but it never stays reving very high. it has new gas and new plugs.

please help

 
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01-04-04, 08:11 AM   #2  
Because a snowmobile is closer to a ATV and a motercycle you should not be placing your question here. You should post your question in the mortercycle ATV forum. This forum is only for LAWN AND GARDEN and SNOW BLOWERS small engine equipment. I dout you will get many answers here.

 
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01-04-04, 09:09 AM   #3  
Jim, I have seen other snowmobile questions here as well, maybe not the right forum..(I don't know either)...but nonetheless I will try to help you out.

What it sounds like to me is a carb issue...how long did the machine sit the last time and did it have old fuel in it? What kind of carb is on that machine? You will probably need to take the carb off and clean out all the passageways...and possibly, depending on what carb...put a kit in it.

Hope this helps!

 
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01-04-04, 10:37 PM   #4  
Hello Jim Wheely!

This forum is fine for your question. It has a small engine, and that's the name of this forum. I think the ATV forum is without a moderator right now anyway.

I agree with Dennis...Your carburetor has a problem...probably clogged and/or gummed up with varnish. Remove it and clean it out well. If the carb is connected to the engine with a rubber boot, make sure it is not cracked. If it is, this could be the cause of your problem as well.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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01-05-04, 11:02 PM   #5  
Good call on the boot Cheese, but typically with a 2 stroke engine, if the carb boot is sucking air(or any air leak for that matter), the machine will scream at high rpm...I would still vote for blockages in the carb....seen way too many old fuel (varnish) problems...especially in sleds....they only get used a couple months of the year.....at least I ice race my lawnmower...lol...

 
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01-06-04, 12:42 AM   #6  
I agree. I've never worked on a snowmobile, but I imagine they are similar to a 4wheeler. I work on 4wheelers when a good customer asks me to, or a friend has one with a problem, but other than that, I try to stay away from them, lol. Too many more manuals, parts books, tools, etc... for me to take them on with the mowers and 2 strokes I already get.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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01-06-04, 05:28 PM   #7  
jim wheely
thanks for the input . i will diffenitly try to to clean the carb. someone else suggested that the tank breather line may be blocked thus creating a vacuum inside the tank . the gas cap is snap on with a latch so i am going to check this as well.
what a great website!
kudos!

 
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01-07-04, 01:14 AM   #8  
Let us know how it goes!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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