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Discussion Starter #1
I've got a 1995 Sportsman 400 and it overheating too. Here's what I've done for trouble shooting; changed the antifreeze, new cap, new fan, washed the radiator. What else am I missing?
 

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Discussion Starter #3
water pump eh. Is there a known way to tell if its working? I also replaced the little sensor on top of the radiator.
 

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Easiest way to tell if the water pump is working? With the radiator cap cap off and the coolant just covering the top of the core tubes, start the engine and rev to about 2000 RPM - coolant should flow over the top of the tubes indicating coolant flow which indicates water pump is working - if there is bubbles or foam in the coolant it indicates a head gasket leak - I've seen them bad enough just pulling on the recoil rope would be sufficient to get bubbles in the coolant and you could hear compression leakage into the cooling system.
 

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I'll try it when I get home. I don't think its a head gasket. Seems to have plenty of power and get up and go - pep. I pretty sure I remember the coolant having a good flow when I had the cap off a while back. But since I'm heading out for a caribou hunt in three weeks I need to know.
 

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Since you're answering questions, as I'm pulling hills after the atv is warmed up it sound like the chain is slipping on some sprocket. I changed both sprockets on the main and the chain, but it still happens.
 

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In what years was this a problem please? I have a 2014 and haven’t had any problems. Thanks[/QUOTE]


They're referring to the 400 Liquid cooled two stroke, not the later model four stroke. :)
 

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Yes - we are talking 2 stroke engines - all years of the 400L engine

The chain slipping? There is a chain inside the gearcase that will wear out and start jumping the sprockets inside the gearcase or (if it's not the chain), the shift dogs inside the gearcase can be damaged or worn and the transmission can be jumping out and back into gear also sounding like a chain jumping.
 

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I think I got several problems ironed out. First the rad was clogged from behind like a mud pie - no air circulating there. Cleaned with spray nozzle several times and pretty clean now. The fan is working. Flushed the rad and hoses with clear water and used CLR on the rad for deposits - got quite a few. Refilled with new 50/50. New spark plug since the old one was a 9 and not an 8. Slipping chain may have been the result of lack of grease. I thought there was a transfer case, but nope. Grease fittings all over in place of. Relubbed all the zerks I could find including the front 4x4 on demand and the front chain housing. Didn't appear to be much in the housing.

Now I'm wondering about how much 2 cycle oil is used per tank of gas and how do I check for flow? I downloaded a manual but there are o specifics for checking.
 

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Checking oil flow from tank to pump; remove hose from pump and oil should drip or run at a fairly rapid rate - from pump to engine; remove hose from inlet port, cap port on the engine, start engine, let idle, hold the pump wide open - there should be a blurb of oil every few seconds - the pump does not pump steadily, it pulses every few seconds. Depending on how often and how long the engine is run, a tank of oil may last a month or more
 

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I think I got several problems ironed out. First the rad was clogged from behind like a mud pie - no air circulating there. Cleaned with spray nozzle several times and pretty clean now. The fan is working. Flushed the rad and hoses with clear water and used CLR on the rad for deposits - got quite a few. Refilled with new 50/50. New spark plug since the old one was a 9 and not an 8. Slipping chain may have been the result of lack of grease. I thought there was a transfer case, but nope. Grease fittings all over in place of. Relubbed all the zerks I could find including the front 4x4 on demand and the front chain housing. Didn't appear to be much in the housing.

Now I'm wondering about how much 2 cycle oil is used per tank of gas and how do I check for flow? I downloaded a manual but there are o specifics for checking.
If the eccentrics are not adjusted correctly (3 of them) then the chain will ride up over the sprocket teeth and jump. The front and mid eccentrics are easy to set. The rear chain is different. You need to get the rear axle, rear arm front pivot and transmission output shaft in a straight line and then set the chain slack. I do this with a large ratchet strap and crank the suspension down with the rear of the machine in the air to check the line and turn the eccentric. Too tight and you'll break a chain on a large bump, too loose and it jumps.
 
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