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Discussion Starter · #1 ·
Hi all, I have just acquired this machine, It has been sitting a very long time but in very good condition. I have been working on small engines for quite some time but have never seen carb sludge like this before. Anyhow I have cleaned carbs and pump twice, replaced all fuel lines and filter, new plugs. Compression is good, only 1200 km. the sled starts fine, idles fine but is extremely boggy up to half throttle, no power at all. It has lots of get up and go at 3/4 throttle but can barely carry itself at 1/4 throttle any suggestions?
I'm thinking of tearing into the carbs again for the third time.
Also it just sounds real strange through the muffler while this is happening almost like it is 4 stroking
 

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I had a 377 Skandic 2 bak in the day. My father gave it to me and said if I could fix it I could have it. It pretty well had the same symptoms as you are referring to. Turns out it was the throttle cable. Only one carb was being operated. The throttle felt like it was good, but one side of the cable after it splits in two was broken. It idled perfect, but fell on its face when you gave it more fuel. I'm not saying this is exactly your problem, but check it out.
 
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Discussion Starter · #5 ·
Thanks for all the help
clean both carbs again then replaced both pilot jets . It now runs and idols perfect!
It still has a strange sound at quarter throttle through the exhaust but will look into that next
I'm wondering if previous owner removed internal baffles for some strange reason. It does look as if some of the joins were re-welded
 

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I'm wondering if previous owner removed internal baffles for some strange reason. It does look as if some of the joins were re-welded
Sometimes it's simple as a over stretched muffler spring can cause a leak & vibration at a certain speed, something else to check is the exhaust manifold bolts to see if they're loose or gone, if a bolt is gone there's a possibility the gaskets are burned as well.
 
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Discussion Starter · #8 ·
Had a bit of time to work at it last night. Here's what I found.... Plug caps only showing 200 ohms of resistance, getting new ones today. What I really think was happening is I've been taking carbs and pump off so often that I was leaving the pump unattached to the body. So where the pump gets attached there is a 1.5 inch hole that goes strait through to the track. After coming back from a test run I noticed that fresh snow was covering all the electrical connections and oil resivoir. after a couple minutes it had all melted and all connectors were totally soaked. I'm guessing and hoping this is why she would always run great until we would hit some powdery snow. Crossing my fingers it's not the stator or coil, gonna run it possibly today and will keep you guys updated.

Suv1...... Thanks for the suggestion
checked all springs again and all were tight, the sound is more of a sputter/misfire
Hoping this fix takes care of it... We'll see
 

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The plug caps are the metal encased ones...or not?
 

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Discussion Starter · #11 ·
Ok so had it out for a run today and it was back to its old tricks
Did some eliminating though, so when the ski doo starts to bog I was always able to pull the pto side cap with no change to engine idle so managed to swap plug wires and problem stayed with pto side. So I then Swapped gas lines from pump to carbs and bingo the problem followed the line. I took pump apart again the inlet port was 75% plugged.
Cleaned pump again put everything back together. Took it for a run and its 90% better
But there is still a misfire/bog that happens briefly when travelling at half throttle almost as if it's loosing spark or fuel momentarily.... Thanks for the help! Any more suggestions?
I may check to see if any debris made its way to the carb again then maybe look into ignition system.
 

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Great job troubleshooting, i say more of that gunk has gotten into the jets, i would clean the carbs again before looking elsewhere.
 
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