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Thread: Reality of a -50 engine start?

  1. #1
    Member akjw7's Avatar
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    Default Reality of a -50 engine start?

    I've got a fuel injected sled that requires a battery. No electric start - but the battery is needed to run the fuel pump and get the injector rail up to pressure.

    I replace the battery every year, check the fluid level regularly, and throw it on a charger every once in a while if it's been sitting.

    Everyone wonders about the reliability of this kind of set up since you'll be stranded if you have a dead battery.

    Sled has sat for the past 4 days of 40-50 below temps - I'll check voltage tonight to see how the battery is fairing...but no test is as believable as pulling the rope and having it fire right it up.

    Finally on to my question!

    How bad is it to start a frozen machine in this extreme cold? Is it not the concern that is in four stroke engines with wear due to lack of lubrication?

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    Moderator AKmud's Avatar
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    It's not a problem if you let the machine warm up for a few minutes. I have seen more than one guy "cold seize" their machine by firing it up and taking off straight across a lake without any warm up time (which = top end overhaul).

    Since the piston will heat up faster than the cylinder, it needs a few minutes to equalize.
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    What machine is it?

    Along with what AKmud says I have always let mine idle until the coolant starts to flow and warm the coolers. Than you know for a fact you won't cold seize. Starting it in these cold temps is fine.

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    Member akjw7's Avatar
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    checking heat exchangers is just so easy - disgusting the way some people abuse their equipment...

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    Member mod elan's Avatar
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    Still wondering what sled or injection system it is? And why are you changing the battery every year? If it is properly maintained it will last for years.

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    Member akjw7's Avatar
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    it's a 580 cat, no battery-less systems on them in the mid-90s vintage unfortunately - they seem like the "cat's meow"!

    I change it every year, simply because it's a $25 battery and I have less critical places I can use old ones...small price to pay for a little extra piece of mind, as a bad battery will leave you stranded

    I spend a lot more than that on synthetic oil and that's more than once a year!

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    Default Flash Point

    While it varies slightly based on the exact formulation of the fuel, gasoline generally has a flash point around -49°F. That means, at -50°F and below, gasoline doesn't give off flammable vapors. So, if your engine and the gas are all colder than that, the gas won't vaporize properly until it warms up. Fortunately, the compression of the engine warms the fuel up in the cylinder very quickly, but much more so when the engine is warmed up. Worst case is you have to prime, choke, and pull the heck out of it for a bit.
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    I know this is a little off your subject. I would carry a small set of home made jumper cable to start or charge you’re sled.

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    I had a 580 Cat Panteria, with the batteryless ignition. Bought this machine new. Right off the bat I told the dealer that I felt it had a bad battery. When cold battery would not start machine. Dealer said that was normal, that when cold you always had to hand start all machines. Dealer kept saying "NO, No, the battery is good". Every time I took the machine out it fouled the plugs. On a typical day it would foul three to four sets of plugs. I could be riding down the river at a good speed and let completely off the throttle and they would foul. I bought a new battery, problem went away. For three years no problem, then it started doing it again. Battery tested good, but would no longer start the machine if cold. Replaced battery, everything was fine again.
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    I DREAD attempting to start a machine a -25*F let alone -50*F. They are so **** hard to pull over. Which is exactly why I installed a block heater for my XCR-800. Engine is all nice and warm, even on the coldest days. Only takes a couple of pulls and she'll light up.

    A hairdryer or one of the small auto heaters that can be placed in front of the motor and the hood closed and cover put on for 10 minutes will go a long ways towards making your life easier. If you are out in camp though...better you than me,
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    Member akjw7's Avatar
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    Quote Originally Posted by Rutting Moose View Post
    I know this is a little off your subject. I would carry a small set of home made jumper cable to start or charge you’re sled.
    from what? I suppose if another sled had a battery you might be able to rig that, but I think you have to be careful as many 12v sources on sleds are not regulated...best bet is a good battery with proper maintenance

    An extreme solution is another battery that you could keep warm somewhere or a generator with a pad heater and charger...I know I don't have room for that stuff when I venture out!

    If I was going on an overnight trip I would carry some handwarmers and if the temps fell to the extreme range I would just put one or two on the battery and call it good for the night - keeping the batteries even 20's warmer than ambient would make a huge difference...

    Also I think not relying on the battery for cranking the engine is a big increase in reliability...think about it - all the battery has to do is provide enough juice to charge the fuel rail then once the sled fires you should be good

    Now if it was an electric start sled that also used the battery for EFI - I think I would only hand start at extreme cold temps...just to save that battery...starter motors draw a lot of amps...

  12. #12
    Member akjw7's Avatar
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    I DREAD attempting to start a machine a -25*F let alone -50*F. They are so **** hard to pull over
    that's one beauty of fuel injection - even at 30 below this machine starts on the second pull...every time! and it's easy to pull too...no flooding, no primer, no choke...

    love it!

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    Moderator AKmud's Avatar
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    I had a Polaris 500EFI for quite a while and the only concern I had was what I would do if I were to crash into something and damage the battery? The battery was mounted right up front in the tub and could easily be damaged if I were to hit a tree (has been known to happen ). If the battery is inoperative, you are done. Other than that concern, I loved the simplicity, but I think the carburated engines are a bit more responsive.
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    yeah it's a possibilty...just like hitting a tree and bending something beyond driveability...or any other of the countless infrequent, but no less possible accidents or problems

    If I had the bucks to buy something new and was doing a lot of really remote stuff...I would probably choose something that didn't require a battery...might be why I'm having a hard time selling mine in this frigid weather!!

  15. #15
    Member akjw7's Avatar
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    Well I went and checked on the sled today, after it has been sitting out through this 40-50 below zero temps for close to a week.

    A respectable 12.4 volts on the battery

    first pull - holy crap that is hard to pull - got maybe a 1/4 of normal pull on it (there is a big difference between a machine that has sat overnight in 30 below and one that has sat for 5 or 6 days at that temp or colder!)

    second pull - holy crap that is hard to pull - another 1/4 pull compared to normal

    third pull - nearly a full normal pull - hooray it's looseing up!

    fourth pull - vroom! fired right up!

    OK now we just need to get through this cold snap so we can get to some fishing!

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