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Discussion Starter · #1 ·
Hi, I'm new to sledding and bought myself a 2005 340 classic last year-Nov. 13, 2005. I was only able to take it out on the lake a couple times. I had a real problem starting it when I first received it and polaris agreed that it needed a new starter-should have been my clue to a "monday sled"! Got it back after 2 weeks, and was finally able to take it out for a day. Now the fun part. After running for about 20 minutes, I came to a stop (engine still on) and it died!! Husband took out spark plugs, cleaned, reinserted them and it started ok. Ran again-stopped and died. This happened 3 times. I got back home and called the dealer I bought it from and they suggested it was old fuel-to try fresh. Well we did that at the end of the season, which for me was that week-end. I only put 100 miles on it. This year, hubby was checking his compression on a new sled he bought (used) and he got a rating of about 100-but it does have 5000 kms on it, he was curious, and tested mine. It got a rating of 90!!!. I called my dealer yesterday, and he said that 90 is normal for a 340. My husband is a diesel mechanic and disagrees. He said it should be rating at least 125, seeing as it only has 100 miles on it. My question is, who do you think is right? do you think the low compression rating has anything to do with it dying after riding it? And, because I am 3 months past the one year warranty, what do you think I could do as far as getting it covered? I am so pissed off, the whole reason I bought a new machine, would be that it should be trouble free. I just want to ride (whenever the lake freezes!) and not worry about fixing things. I feel so ripped off. Any suggestions? Thanks everyone
 

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If your sled only has 100 miles on it the rings may not be fully seated into the piston bores. They do take some time to "wear in" and develop full compression. If you have been "babying" the throttle to break it in and using synthetic oil it will take a while. Full throttle 15 sec blasts are best for seating rings. I break my sleds in on the race track. Quick blast to warm up the track and then 11 sec blast. Ride for another 200 miles and recheck the compression before you get too excited. As long as both cylinders are within 10% it will run fine. Same goes for the plugs. If you continue to run at low "heat levels" in the engine you may consider a "hotter" spark plug. BR7ES. Have your husband read up an "reading" spark plugs and pison wash, they tell alot. Snow engines need a little tuning for different conditions.

edit: spelling
 

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whats the elevation where youre at? the 90 psi may not be bad. you cant justify the compression test on a 340 to say that of an 800. different motors have different compression. i have a stock 800 with 130 and my mod runs 165 psi. same style motor.
 

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whats the elevation where youre at? the 90 psi may not be bad. you cant justify the compression test on a 340 to say that of an 800. different motors have different compression. i have a stock 800 with 130 and my mod runs 165 psi. same style motor.[/b]
^^There elevation is under 1000 feet^^


Have your husband borrow another compression gage. I got 5 bucks that says you gage is reading low.

Edit : By the way :welcome:
 

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Discussion Starter · #5 ·
thanks for quick replies! Yeah, I was babying it as far as breaking it in, but was advised to keep it "low speed" for first few hundred miles. Spark plugs were fouling a lot, so maybe a hotter spark plug is needed. As far as his guage on compression tester, he tested his 580 (with 5000 kms on it) and got 110. Then he tested our 10 year old skidoo -380 (never rebuilt) with 5000 kms on it and it registered 125 each side, so even if his guage is out, I would think that my brand new polaris should read better?? Do you think that "unseated" rings would be the cause of it dying after running it for 10-20 minutes? Thanks again everyone-great forum for this "newbie" and I can't wait for the lake to freeze!!
 

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Discussion Starter · #7 ·
The first time, hubby just cleaned the plugs with a wire brush (which he carries on his sled), the second time he changed to new plugs and the third time he cleaned the second new plugs.??? Did this with both.
 

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was/is there oil in the gas tank for break-in? Stop babying it and carry some br7es for the next time they foul. Read the spark plug color and adjust jetting accordingly. Small fan cooled engines are kind of fussy on appropriate jetting for the conditions. New set-up is for -20 to -40 F @ sea level. There is some wiggle room to decrease fuel delvery in the carburator. Is the oil pump set correctly? The arm has two lines on it that should line up with a boss on the oil pump at idle and WOT.
 

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the oil in the gas could be giving you youre problems. im still unsure why people do this or tell people to do this. for one, its probally the cause of your fouled plugs, specially if youve been riding slow. get out and get on it. run the hell out of it. but only short bursts. add some gas, try to get that oil mixed crap diluted.
when oil is added to the gas in an oil injected sled, it has been known to build up heavy deposits in the ring grooves. again this from the mixture being to rich and fouling alot.
my suggestions...get the fuel mixture back to straight fuel, start adding gas.
get it out and give it some throttle. let the motor heat up, but dont hold wide open throttle for extended periods
you can run a hotter plug for now, but once you get it cleaned up pay close attention to the plug and id proballly drop back to the original plug. but the hotter plug should help get it cleaned out.
 

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Discussion Starter · #11 ·
Just an update-I feel I'm getting the runaround. Hubby was pissed with the reply we got from Polaris (low compression is normal for a 340) and we took the machine back to dealer to look over. I got a call from the mechanic saying that he got a compression reading of 115 and that was normal for a 340. Again I replied that the engine size shouldn't matter in the compression test-he argued. So, basically he is saying that my husband's compression tester is wrong. This is the problem-we tested our old skidoo 380 with the same compression tester-didn't warm it up at all and got a reading of 125 per side. So assuming that hubby's tester is 25 out (we got 90 per side on my warmed up machine)-so our old skidoo is reading 150 per side cold? This still doesn't seem right to me. Hubby is fed up and just wants to pick my machine up. How do you argue with the polaris mechanic? Should I sell it? As far is it dying when riding it last year, when I phone after it happened, he suggested that it was old fuel in it. I asked him again about it and he said the belt was tight and that would cause the engine to fail. Shouldn't that have been checked with the pdi when I bought it? We have new fuel in it now, so I guess I'll pick it up and hope for snow so I can see if it is running any better. As far as the compression test-do I accept his 115 per side or out 90 per side and live with it? Does this show engine damage? What is the normal compression test for a 340? Thanks again-helps to vent!
 

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Yes, compression testers can vary that much. and Yes, some ski doo's have higher cranking compression. and Yes, you can take a small flashlight and inspect the bores from the spark plug holes for damage if you really think something's up. and I have never argued with any mechanic, just take their advice and move on. and No, don't sell it. and Yes, the belt is too tight ONLY if the sled squeals or moves at idle. again... Your sled has low miles, get out in an area where you can really goon it, and break her in, the sled that is...
 

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To check of the belt is too tight, start it with the track off the ground. If it spins quickly, it is too tight. Be sure it is not idling too low, this will foul plugs quickly. If it has a tach, have it set to idle around 1800-2000. It should have BR8ES plugs in it. To break the engine in, it should have 3/4 of a quart of oil in the first full tank, and fill the oil tank. Run that tank through, ride it normally, don't baby it, and definately hit it full throttle a few times. Then before going to your first tank of straight gas no oil in it, check that the oil tank level has dropped.
 
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