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Discussion Starter #1
I'm fairly new to snowmobiling, and have a 98 Polaris XC 700. I'm not familiar with jetting, so could someone elaborate to me please on how it works, how I have to change the jets I guess, and what whould cause me to change them. As, I'm fairly new to this, what else should I do to the carbs to make the engine maximize all its potential?
 

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just so you know, rejetting can be a risky game to play!! and expensive I.E.(a melt down)
rule of thumb:
the leaner (smaller size jet) you can run, the better (more responsive) it will run....the draw backs, temperature...too cold and a melt down, at higher elevations, the air is thinner so you can jet down fairly safely...as the temps warm up , you can jet down as rule...
the fuel is mixed with air through the jet..as the temp, elevation, atmospheric pressure change, so does the way the fuel/air mix goes through your carbs.
so be careful, do plug checks, but,......
be prepared for the worst, unless your a serious hard driver, stock is probably a good all around happy medium!!
ride on, ride safe!
 

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If you don't know what you are doing with jetting don't touch them. just my $.02
 

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my opinion is if you want to go faster buy a bigger sled.
I run the same jets all the time
when I'm outside the temp range of the jet I'm running I try not stay at the same speed for too long, crack it wide open for a few seconds
to clean it out
 

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I agree 100% with the above. Don't touch them unless your previous owner messed with them, which means they may be set too lean.

-Dean
 

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Discussion Starter #6
so are the jets something that I have to physically change when I get a new pipe and can? how do I read plugs to tell if its too lean or too rich a mixture?
 

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Yes, think of changing jets as changing how much water flows out of your garden hose. Say your stock jet is a number 300, consider the water valve at 1/2 open. When you lean out the mixture (usually for warmer air which is less dense which means less air flowing through the carbs) by going to a 290 jet you have just closed the valve. By richening (colder air, or performance mods which make the engine flow more air) to a 310 jet you have just opened the valve. The key with jetting is to keep the air to fuel ratio correct. Too rich and it will bog, foul plugs and smoke more (but run cooler). Too lean and it may bog because of a lack of fuel and run hotter but a lean mixture gives you the most power. 2 strokes run awesome on the lean side for a little while...then they go pop. There are different areas of the carb that you can change the jetting. Main jets adjust from 3/4 to WFO. The slow jet controls 1/8 to half and the needle adjusts from quarter to 3/4. To change the main and pilot you must remove the carb, probably, and remove the float bowl. The needle you can change by unscrewing the slide. You adjust jetting by the ride and feel method and by the spark plug color.

Check out [red]http://www.ericgorr.com/techarticles/carbtuning.html[/red] it's a great site for jetting!
 
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