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I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

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I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

Postby Kesterman » January 23rd, 2005, 2:37 pm

My Ski Patrol friends use an Arctic Cat, Bearcat sled powered by a 440cc Suzuki air cooled engine for emergency runs to haul in injured skiers. It's used on a small hill, and seldom runs at more than part throttle.
It gets fired up, run to the incident, let idle for five to ten minutes, run back to medical at very low throttle settings, idled for a minute or two, and then shut off. It never gets run hard (meaning large throttle settings) and in the area available, it would be impossible to run at full throtte for more than ten seconds.
It's operated by people unfamiliar with hand chokes or even cars, for that matter. Would hotter plugs or some other simple mods make this start better or be a better runner under these conditions?
Thanks
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I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

Postby craze1cars » January 24th, 2005, 12:10 am

That all depends on how it's running now. Are they having problem with it fouling plugs or something? At 1/2 throttle or less, it can be leaned or enrichened a certain amount by simply adjusting the air screw on the carb. Pilot jet is the other change that can be made. And yes, a going to a hotter plug will help it prevent fouling (if it's having a fouling problem,) but could potentially cause other problems. It'd be easier to offer a suggestion if I knew more specifically what, if anything, it's doing wrong.

BearCats are designed as utility sleds and are factory spec'd for this type of use much better than a more performance oriented trail sled like you're used to. So it might not need anything changed at all.
Body Armor SAVES LIVES!!!
COURTESY on the trails is CONTAGIOUS!!! Slow down EARLY for oncoming sleds!!!
ONLY pass from behind when signaled to do so!!!

THEN.....and only then...RIDE IT LIKE YOU STOLE IT!!!
craze1cars
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I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

Postby Kesterman » January 24th, 2005, 2:28 am

Yes, it fouls plugs on start up, and then the plugs have to be swapped out. The operators aren't really mechanically inclined, and tend to screw up the choke process. Anything to make it fire easier would help.
It never runs at full throttle for more the a few second, and never really gets warmed up. It idles more than it's driven.
Once it gets running it seems to be ok.
Kesterman
 
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Joined: January 23rd, 2005, 1:53 pm
Location: Michigan City, IN 46360


I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

Postby craze1cars » January 24th, 2005, 3:46 am

Even if they're overchoking and flooding it, it shouldn't cause the plugs to foul so they need to be swapped out. That leads me to believe that they are most likely oil fouling as opposed to running too rich on the fuel mixture. The nature of a 2 stroke is that when they're idling, the crankcase gets a lot of oil gradually building up in it. Then when you hit the gas and the RPMs get higher, it throws off that excess oil and burns it away out the exhaust. If there's too much oil built up in there from extensive idling, and then they rev it just a little and it all gets thrown off at once, it'll likely foul a plug. This can sometimes be helped by going one step hotter on a plug. For instance, if they're running BR9ES, change them to BR8ES. Changing to the expensive Iridium plugs would likely help it, too. And maybe turning down the injector pump so it doesn't put in so much oil...but that's a little more risky if you don't know exactly what you're doing.

I realize they probably can't affordably buy another sled, but this type of use is perfect for a 4 stroke application. They'll idle all day long without any problem at all. Hope that helps a little.
Body Armor SAVES LIVES!!!
COURTESY on the trails is CONTAGIOUS!!! Slow down EARLY for oncoming sleds!!!
ONLY pass from behind when signaled to do so!!!

THEN.....and only then...RIDE IT LIKE YOU STOLE IT!!!
craze1cars
Member
 
Posts: 47
Joined: October 5th, 2004, 10:28 am
Location: Wherever snow is deepest...

I need help, guys! Spark plug choice for repetitive 10 minute, low speed runs

Postby Kesterman » January 24th, 2005, 6:14 am

It helps a lot. Thanks.
They've actuelly gone to a 4 stroke as their primary sled, but they use this one a lot.
Kesterman
 
Posts: 1
Joined: January 23rd, 2005, 1:53 pm
Location: Michigan City, IN 46360


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