Snowmobile -> Mechanical Advice Needed... :)

[brandon184]

For those who know about the mechanics of a snowmobile...

I have a '92 Polaris Indy 440, which I either want to fix and make useful or fix and sell, as I'm heading back up to where the snow cover lies, and the two stroke fumes are a welcoming daily scent... Either way, it needs to get fixed. The problem is, that in higher temperatures - it bogs down horribly. If you take it out on a colder day, it will run fine - all day long. But if it's a warm day, you can expect it bog down - guaranteed.

Anyway, you can shut it off for a few minutes, start it up - and work fine, until the next time you come to a stop. And the cycle repeats...

Knowing little, other than how the engine and other basic parts work, I've taken it to the shop several times (I've probably taken it in 5 times, between 2 shops... One being an Arctic Cat dealer, so I'll say no more...) Of course, I get the "It's fixed - it need a ______, so that'll be $150..." Only to take it out the next day and find that absolutely nothing has been fixed.

If this sled wasn't anymore than a casual rider, and was my only sled - I would probably have had a brain aneurism by now. So, I'm trying to gather some ideas from people who might know what this issue might be, and I'm going to take it in within the next few months, drop it off and have a mechanic ride it in warmer weather if all else fails...

Any info/insight is appreciated!

- Brandon
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~XP

[bigblue77]

Sounds like a carb problem to me, but since I know nothing about Polaris sleds, I can only offer that as a starting point.

Jer

Sounds like a Mntsnow question.. I sent him a link to this thread.

[Mntsnow]

Brandon,

Yep...Me love my Polaris sleds but now that your in Cali I take it your going to have to "trailer" your sleds somewhere?

But back to your question.... Yes I bet your main problem is carb settings. Do you know what size main jets and pilot jets and of course Needle and jet needle sizes you currently are running? Can you find out if you dont? Also what elevation are you going to be mainly riding at? A 2 stroke engine is very sensitive to elevation changes and temps as they both effect the air density and thus your Air/fuel mixture.

I have a chart that can tell us where you should be approximately once I know the Temps and Elevations you primarily ride in.

Also another thing that will effect how your sled performs is how you set the clutches up....If you have the clutches "come on" to fast you load the motor to hard and it will cause it to be sluggish...I you have the clutches come on to slowly you loose top end and increase the chance of burning the drive belts.

Do you know what size Helix you have in the secondary clutch and what spring you have in there with it? What Cam arms and spring do you have in the primary clutch? Is there any engine work done such as Aftermarket Pipes or head milling work done?


Let me know...I'll watch this thread a bit closer

Thanks Socal for bringing it to my attention

[Richard Cranium]

Since I'm a car mechanic, this is generic info.

Sounds like "Vapor Lock" or a failure of the condenser or coil.

The ignition system parts, i.e. Coil & condenser will "Open" up at elevated temperatures when bad and "Close" again when cooled. The Condenser is attached to the points and absorbs the power so when they open up there is no arcing.

The coil is less likely suspect, however you can remove the coil wire when it goes dead and spin it over to check for spark, don't try to make it jump more than 1/4" , excess resistance may cause failure of other nearly used up ignition components.

Vapor lock happens when gasoline boils in the fuel lines. If the lines have been moved from the original factory location, move them back if possible. Warning, fuel leaks in engine compartments can prove fatal.

Snowmobiles probably have some type of exhaust heat recircualtion to aid in atomization at cooler temperatures, this device's temperature control wax pellet may be faulty, a question for Meestor MtSnowMan

cya
Doc

Seeing MtSnow's post reminds me of my usage of a Gold Sluice box powered by a 3hp 2-stroke gasoline motor.
It was jetted for 600' altitude, when ran at 8,800' of the Arkansas River in Lead Colorado the poor thing would run for about 15 minutes then foul the plugs.

[caddmannq]

Exactly what parts have already been replaced?

Excess fuel could be a prob. on warm days. Soggy or leaky carb float, & poor float adjustment are common problems with 2 strokes..

But I haven't owned a snowmobile in over 30 years. Does a '92 have oil injection? Excess oil could be a factor.

But what exactly do you mean by "bog down"?

Does it ever reach full RPM on a warm day? Is it just doggy comming off the line?

[Richard Cranium]

Cadd's hit an important point..

On 2-stroke engines the float level has an enormous effect on air/fuel ratio

Think of the float level like a hydroelectric dam, the more water height, the higher the pressure on the turbines.

Same principle in an engine, saturated floats cause high level conditions, this and the pressurization from float bowl bleeds cause excess fuel, i.e. rich running soon fouling plugs and causing sluggish running leading to engine stop.

Float level changes are the easy way to fine tune a/f ratio without changing jets.

[brandon184]

Mntsnow -> I'm heading back to Canada this winter! I'll have a look at what you asked me about, and get back to this thread.

Richard Cranium -> Someone else (I don't recall who) also said something about vapour lock, but no dealer has ever said anything to me about it. I've had 100 different people tell me 100 different things, so I have trouble anything too seriously. Everyone has their theories.

caddmannq -> There's really only been two things that have been replaced. The first being a part with the fuel line, and the second being a part regarding the fuel tank. I don't exactly remember specifically which each part was.

When I say "bog down", I mean that you can stop, hit the throttle and the engine will give a throaty growl as if it's accelerating (keeping in mind that the sled isn't moving), and then just peter out into an idling state, even if your still pinning the throttle. I shut the engine off, start it up 5 minutes later - and it takes off, no problem. Low/Moderate/High speeds are absolutely no problem, but if you're going really slow, or have come to a stop - it'll bog. Once you get it up to high speeds, it'll performs well.

- Brandon
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[caddmannq]

Sounds like they replaced the fuel tank strainer and maybe the fuel pump. The strainer tends to clog up when you let the thing sit all summer. The pump just gets weak with age.

OK...when it boggs, does it belch black smoke out the muffler?
Or does the exhaust smoke actually diminish?

When this happens, does the rpm diminish smoothly? or does it chug-chug-chug & die out?

[brandon184]

Nope, no black smoke. When it bogs out, it'll just chug-chug-chug - Then it's done..

- Brandon
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