Extreme Cold=Lean?


Thanks for all the info :rockon: The only reason I was out at these temps is myself and a few buddies took a trip north, trails were f**king MINT.
 
Bushman said:
I am shooting from the hip here but from my Mikuni jet chart I think 20* was worth 1 jet size. If you are jetted for 0 & it drops 20* you would need to go up on size main, If you went up 1 clip richer on the needles you actually needed to lower the clip 1 groove & the you can also do half clip adjustments with the washers. Stock jetting was 147.5's for the mains ?
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In the tech pages it says 156.3 stock jets??
 
Bushman said:
Thanks thats what I was thinking, Sounds like chit fuel or water to me. Is this the same cylinder?
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Last year was the centre cylinder, This was the PTO side??
 
Fireman77 said:
In the tech pages it says 156.3 stock jets??
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No wonder why I have so many 156.3 jets in my kit, We piped 3 of them. Stock jetting is way fat from the factory to prevent burndowns due to cold weather/poor fuel. I would bet you will find water in the carb float bowls/gas tank. You did not by chance add NYTRO octane booster did you?
 
RIVERRUNNER said:
yes...higher the number the richer it is....do you have a manual for your sled?? Are you going to put it back together? If you are, you need to check your plugs and piston wash at idle, 1/4-1/2 throttle and at wot. Like they said above...jet for the absolute coldest your sled will ever see maybe a little colder..I will not run the best in warm weather, but you will not melt it down...Then when you do go out on a really cold day that you are going to be holding it to the bar across a field or lake it is a good idea to check your plugs after 15 min of riding before the wot runs, just to make sure you are safe....just my 2 cents...Good Luck....RR
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Yes I have a manual. I'm not sure what you mean by piston wash? Thanks
 
Bushman said:
No wonder why I have so many 156.3 jets in my kit, We piped 3 of them. Stock jetting is way fat from the factory to prevent burndowns due to cold weather/poor fuel. I would bet you will find water in the carb float bowls/gas tank. You did not by chance add NYTRO octane booster did you?
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No, never added anything to the gogo juice?
 
Another link to piston wash pics.

http://www.totallyamaha.com/snowmobiles/aaTECH/Piston_Wash/Piston Wash.htm

I have been fighting some issues with jetting also. Rode in Big Horns with MJ-#143.8 PJ-#55 JN-2.5 PS-2 1/4. Burn down on Mag side. Mechanic that rebuilt claims lean burn. Should have been OK according to 2005 Chart (which I have), but still lean burn. Identical sled with same jetting towed dead sled back 15-20 miles and it didn't burn down. Going to inspect pistons on that one later today. If you have a small LED light, you are suppose to be able to look at piston wash, to some degree, without pulling heads. As most have told us, check plugs by running down trail and hitting kill switch (Don't forget to hang on!!!!). Pull plugs and inspect color to help identify the type of burn. White or light color is lean, dark is rich, and in between (or close to a cardboard color) is supposed to be correct. Not the tech that some guys on here are, but we learn as we go. Hope this helps.
 
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SXlover said:
Another link to piston wash pics.

http://www.totallyamaha.com/snowmobiles/aaTECH/Piston_Wash/Piston Wash.htm

I have been fighting some issues with jetting also. Rode in Big Horns with MJ-#143.8 PJ-#55 JN-2.5 PS-2 1/4. Burn down on Mag side. Mechanic that rebuilt claims lean burn. Should have been OK according to 2005 Chart (which I have), but still lean burn. Identical sled with same jetting towed dead sled back 15-20 miles and it didn't burn down. Going to inspect pistons on that one later today. If you have a small LED light, you are suppose to be able to look at piston wash, to some degree, without pulling heads. As most have told us, check plugs by running down trail and hitting kill switch (Don't forget to hang on!!!!). Pull plugs and inspect color to help identify the type of burn. White or light color is lean, dark is rich, and in between (or close to a cardboard color) is supposed to be correct. Not the tech that some guys on here are, but we learn as we go. Hope this helps.
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take pics of your piston.
 
did both sleds fill up at the same gas station?

what grade gas are you running? whats the octane?

so you richend up the needles to the 4th groove down? , where did you place the plastic shims?
 
mrviper700 said:
did both sleds fill up at the same gas station?

what grade gas are you running? whats the octane?

so you richend up the needles to the 4th groove down? , where did you place the plastic shims?
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All three sleds filled up at the same station, 2 on the same pump? The other sleds were EFI Cats?
 
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