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Discussion Starter #1
I have a 1977 ski doo tnt 440 fan cooled sled,it runs good for its age but the problem is that when i go for a ride say 40 min or around the yard i come home,shut it down...go back to start it up and the clutch side plug is oil fouled...everytime...
i checked the other plug and it is wet with oil but it doesn't foul..I dont have any problems starting it with new plugs,usually 2 or 3 pulls.at idle it does seem to have a bit of a miss but when i slam the throtle there is no hesatation and sounds great....any ideas or suggestions..I'd hate to take it to the shop and spend 200 buck there.....thanks Dan
 

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does that have 2 carbs? You will get more responses if this is moved to the performance tuning shop instead of the how to section.

Welcome to SF!
 

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Discussion Starter #4
Today i removed the carb and WOW you would not believe the brown crud that i seen.I removed the jets and they were caked with dirt and old fuel..Waiting on my new spark plugs today and will reasemble the carb later today.does anyone know the setting for the air screw?? i'm guessing 1 1//4 to startout with...oh ya the air screw was turned in all the way...this is how i bought the sled and it ran....
 

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Discussion Starter #5
I replaced the carb after a good cleaning and put in new plugs,adjusted the air screw to aprox 3/4 out and now the plugs are getting the nice tan look.I guess the carb was the problem.Engine still has a miss at idle that i need to work on.And there is a knock..not sure if its because its off time or if its a rod.Will being off time cause a knock????
 

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probably not ,may also want to put a small inline filter going to the carb ,I think this sled may have points?
 

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Check you rings pistons and rods ifs its knocking and only fouling on one side it could be internal



Driscoll Racing
 

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Discussion Starter #8
Well i just fouled a plug on the other side now.I do have a filter inline going to the carb,and i just replaced the filter and hose that are in the tank.After adjusting the air screw the other day (out more)it seems to be ok but i only took it for a ride around the yard..started without a problem.. The knock is only at idle to about 2000 rpm then it's gone.it's idle is at 1200.The guy at the ski doo dealer says he thinks it that the carb is out of adjustment!!! any ideas guys I'm thinking timing
 

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Discussion Starter #9
going to rebuild this engine as i think the rod bearing are bad.I'm going to do both the topend and bottom...any suggestions on where to start and what to look for????????also does anyone know a cheep place to get part for this engine ??? thnaks
 
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