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Old 12-01-2010
Rubi's Avatar
Rubi's Info
Join Date: Nov 2007
Location: Alexandria, MN
Posts: 3,617
Default Sled is running like crap.

So my sleds have been started up the last few days. RMK runs great and rips around the yard just fine. XC ran crappy before I jetted for MN, now it runs real crappy. Since the RMK runs great, I don't think it's a fuel problem. Sleds were filled up with the same gas on the same day, were treated with the same fuel treatment, and were stored on the same trailer. The XC is usually pretty tempermental before it warms up, but yesterday I rode it until it was fully warmed up and it still ran bad.

At idle, the sled runs rough. It sounds like a race car with a bumpy cam. Also, it backfires a lot. Just small backfires, but they are sort of continuous. Flames shoot out the exhaust, which is more cool than LED's, but I'd rather have a sled that runs smooth than looks cool. I adjusted the fuel screws in and out half a turn from where they were, and neither adjustment made any difference. The sled flat out RIPS when it is above quarter throttle! I put some radical new clutch weights and springs in and they make this sled a beast. I think traction will be a real problem with this setup.

So I know people will say clean the carbs and put fresh gas in. I already had the carbs out, and I'm sick of messing with them. The other sled runs fine, so I think it's something else. How does timing get messed up? I think it seems like a timing issue. Motor seems to fire at the wrong time which dumps unburnt gas into the pipe. Maybe I'll make a video of it. I watched a video of a sled on SF, and I could tell by sound that it was a lean bog. Maybe if I made video , someone would recognize what is wrong?
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