Jetting??

[maxindy]

What is jetting evrey one is talking about it and i dont know what it is and is there every sled that need to be jetted

 

[boots]

well jetting is the fuel to air ratio.... no not all need jetting for the efi takes over...

 

[RUDY]

well jetting is the fuel to air ratio.... no not all need jetting for the efi takes over...

Exactly,you have to rejet for different temps,and elevation...Honstly a pain is the A$$

 

[maxwell]

what sled? since ur in the skidoo forum it might have DPM and no need for jeting!

 

[Modman]

You're in Ontario right? I wouldn't worry about jetting unless you want to re-jet for spring conditions due to the warmer temps. Otherwise you probably don't have enough elevation change to make a difference for jetting. You can re-jet from stock settings but there is so much more to it than just swapping jets. Try a google search on 2-stroke jetting and read some information before trying anything.

Maxwell - I'm guessing that since his user name is maxindy - he might have an older Indy without DPM.

 

[maxwell]

didnt even catch that hahahahah

 

[maxindy]

You're in Ontario right? I wouldn't worry about jetting unless you want to re-jet for spring conditions due to the warmer temps. Otherwise you probably don't have enough elevation change to make a difference for jetting. You can re-jet from stock settings but there is so much more to it than just swapping jets. Try a google search on 2-stroke jetting and read some information before trying anything.

Maxwell - I'm guessing that since his user name is maxindy - he might have an older Indy without DPM.

Well yes i have an old indy but i am looking to buy a mxz 440 but people talk about jetting alot on this sled?? and what is DPM??

 

[maxwell]

im not sure if those race sleds have dpm or not

anyways

i think it stands for "digital performance management"


basically "jetting" controls the amount of fuel the engine gets at top end range.

its a little screw with a hole in it thats in the bottom of the carb.

if you ride in the flats im sure its fine but come to the mountains might have to CHANGE THE jetting...2 jets one in each carb

 

[Sleeper700]

Altitude and Temperature changes have an effect on the fuel/air ratio that your carbs allow into the engine. For example, in Ontario, you are at very low elevation (my assumption), and if the weather is warm right now, you will have very dense air. This means that you will get a lot of air in your engine compared to fuel. Now, if you go somewhere with higher elevation, and maybe much colder, you will have thin air. This will mean that you are getting a lot more fuel than air into your engine. There is a happy medium for the fuel/air ratio. Too much fuel = rich - boggy engine, not very responsive (but usually safer to be "rich" than "lean"). Too much air = lean - increased chance of knock (gas exploding in cylinder before it should) and much higher temperatures. If you run an engine lean too long, you will damage it very easily. So, the "Jets" in carbs function as a flow controller for the fuel delivery. Bigger Jet = more fuel. Most carbed sleds either come with a chart that tells you what the manufacturer recommends for jets at certain altitude/temps. Some machines are quick to change the jets, and others it is a pain in the a$$. There is a bolt on the bottom of the carbs that you have to undo, then catch the gas that will drain from the carbs, then remove the old jet with a small socket or jet tool, and put the new one in and put the cover back on. Ski-doo put their "DPM" (Digital Performance Management) on some of their sleds since 1997 (Summit's had HAC for a couple of years). There are very few models since the early 2000's that don't have it. DPM controls the fuel/air mixture automatically. That way you can just jump on and go. For the most part it works really well. You never have to worry about changing jets with it.

I hope that this explains the concept of jetting and DPM for you.