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Discussion Starter · #1 ·
Having trouble with 440 multiple meltdowns......cylinders redone .....carbs cleaned.....crankseals replaced.....what next?

Only happens at full throttle.
 

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Discussion Starter · #3 ·
All jets are original from the factory and i have owned this machine from new.
 

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could your oil lines be clogged....or ive heard if u switch types of oils used and mix em, u can blow up ur sled
 

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Discussion Starter · #7 ·
Oil lines are good and even adding oil to the fuel to make sure......anything else??????
 

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Are you melting both pistons or just one . You could have a vacuum leak . I saw one with a crack in the line from the crank case to the fuel pump do that .
 

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Discussion Starter · #9 ·
Thanx I'll check......it has been mostly one jug at a time but it has been both....after the both went I changed the crank seals just to make sure, then I blew the clutch side jug.....new jug on jetted up to 300 from 290 and not holding it wide open for the moment checking the plugs regularly.
 

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After the rebuilds are you breaking in the engine properly?
No wot, vary throttle as much as possible for at least 1 tank full, and no wot on 2nd tank.
That sled is liquid, is the water pump OK, plugged lines or exchanger?
Does this happed in low snow or icy conditions?
What did the plugs look like after each meltdown?
 

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Discussion Starter · #11 ·
I am following the break-in procedure and the plug is indicating a lean mixture on the jug that melted. The other plug was perfect.

Snow condition at the time was loose powder at about -15C.
 
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