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Discussion Starter #1
tuned my sled had it runnung great the thing ripped all over started first pull did trackies for a long dist. no hessitation nothing. had to work on wifes sled finally after a ton of carb trouble it starts runs and rips perfectly. then as soon as we wanted to go out my sled is running like crap starts right off and idles perfectly but bogs as soon as the clutch puts any load on the engine whatsoever sled lurches a foot then stops.

took carbs that were freshly cleaned and tuned the previous season were immaculate. fuel lines all good no air in the system. when the sled has the track suspended in the air it still bogs for a moment then gets going up to full rpm range

bogging at 1/4-1/2 throttle sled wont move. spark plugs will be replaced today, just to eliminate that. could it be that the sheaves on the clutch need cleaning? the cluch looks like its in the proper takeoff position. the fuel punp could fuel a dodge 440 big block already checked that. i'm like one second away from bringing it in and paying someone a lot of money to fix it . that is if i can dig it out after the blizzard we just had here in mn
 

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Well, the pilot jet is for the first 1/4 throttle and idle.
If that jet is clogged, it will not idle well if at all and you have to "tickle" the throttle to get the rpms up enough for the mid range jetting to take over.
Use a piece if fine wire to ensure that the pilot jet is clear.
 

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Discussion Starter #5
I'm really starting to wonder if the engine side boots or boot has a crack because i have cleaned the carbs so meticulously including using the fine telephone guage solid strand wire
 

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Discussion Starter #7
i do have a mild clutch upgrade where it grabs at 4500 -5000 rpm for a snappy launch and it revvs up to 3800 4200 b4 it begins to bog i'm also a bit confused just because it ran so well before and now it just wont go
 

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Discussion Starter #9
the belt is brand new i had just enough riding last season in march to break it in and that is hard to believe the belt would deteriorate after the sled sat for two weeks when it ran and grabbed perfectly. the sled did sit outside during a couple moderate snows i did wonder if moisture could have been a problem
 

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Pull the primary apart and clean it.
 

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Start by cleaning the carb real good, including the pilot jet( up in the tube) and the sand down the clutches and blow them out real good! Then check your center to centers on the clutches. You want the belt as tight as possible to give you the largest ratio at take off, and it will also give you the most top end as well!
 

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Discussion Starter #12
i've been thinking about it all day long and the clutch Cant be the problem it worked perfectly for me at the first snow of the season although the carbs did also did my riding and let it sit for a week or two while i worked on getting my wifes sled ready and tuned up. last i rode it it was 20 degrees out now its been between 10 and -5 degrees, when i took the carbs off i noticed a creamy white goooe on the intake side of the carb kinda looked like thin cake frosting. must be a moisture thing.


I've rebuilt and tuned dozens of sleds and i've never been stumped b4. I guess i'm probably over thinking it all. i know however the smallest speck of dust or grime will screw up a carbs function and i've had the jets out of the carb just to make sure i'm gonna check the engine side boots for a vacuum leak as well change plugs and try again . sometimes it just takes a few tries i suppose
 

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Discussion Starter #13
I finally solved the mystery of the problem , The needle jet ! although it looked clean under a magnifying glass untill i removed the needle jet when i discovered the small ring around the top that keeps the needle jet from comeing out the bottom of the carb into the float bowl had corroded internally .that small ring on the needle jet that keeps it in had seperated from the body of the needle jet. this screwed up my afr bad . problem may have been caused by the previous owner overtightening the jet causing a crack and accellerated corrosion. I will have to stop at the snowmachine shop and get a set of main jets and and needle jets possibly new jet needles

also my main jets are 310's i'm gonna check the chart but i'm usually riding at 850' elevation 10-20 deg ferenheit do 310s sound good ? i dont have the sled or its chart on hand
 

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Discussion Starter #14
pics

I finally solved the mystery of the problem , The needle jet ! although it looked clean under a magnifying glass untill i removed the needle jet when i discovered the small ring around the top that keeps the needle jet from comeing out the bottom of the carb into the float bowl had corroded internally .that small ring on the needle jet that keeps it in had seperated from the body of the needle jet. this screwed up my afr bad . problem may have been caused by the previous owner overtightening the jet causing a crack and accellerated corrosion. I will have to stop at the snowmachine shop and get a set of main jets and and needle jets possibly new jet needles

also my main jets are 310's i'm gonna check the chart but i'm usually riding at 850' elevation 10-20 deg ferenheit do 310s sound good ? i dont have the sled or its chart on hand
here are the pics to show notice the cracks and corrosion
 

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