SnoStuff exhaust question

[Meat-Run]

I picked up a SnowStuff can for my sled and when I first start it up it sometimes back fires or pops more then what I think it should do. After it's warmed up it doesn't do that and my buddy has one and it never does this is this something that could lean out my engine or do any harm???

mr

[Macgyver55]

Normally changing the can wont require jetting as a rule, but the fact that it is backfiring is an indication that something isnt right on. Once in a while is not a big deal but it shouldnt do it regularly. Changing anything on the exhaust can theoretically change the back pressure, but cans are beyond the expansion chamber where it matters most. They usually just make sleds louder and do little or nothing for performance IMHO. It could be one of the carbs is dirty, or a pilot jet is plugged or something. It probably wouldnt hurt to go through them if you havent, and then after a good run check the plug color to see how they look.

[Meat-Run]

It only back fires once or twice when starting after it's been running it never does it again. I'll try new plugs and see what it does after that, thanks for the advice. Oh just another tid bit theres just a small amount of blow-by where the can and main muffler connect, again once warmed up and hot it's sealed tight maybe that has something to do with it!? maybe? maybe not?

mr

[Macgyver55]

Quote:

Oh just another tid bit theres just a small amount of blow-by where the can and main muffler connect, again once warmed up and hot it's sealed tight maybe that has something to do with it!? maybe? maybe not?

That is a possibility, I normally put a small bead of high temp silicone on the connections when I put them together. I'd do that anyway if I were you, no exhaust leak is a good one!

[JosMN]

What year is your sled Meatrun? Does it have Kehin carbs? My ol 98 xc700 did this when I first got it. Ran an MBRP can on it, boy did that sled rip your arms out and sound good! To get rid of the backfire just bump up your pilots a size or two - this also takes care of the low end stumble the kehin carbs are known to have. You may have to back off the fuel and air screw a tad if you do bump up the pilots to find the sweat spot. As far as the blow by, just seal the connection up with some high temp gasket sealer.

[Meat-Run]

Awesome advice guys, JosMN it's 2001 700 SKS non-ves and don't know what kind of carbs I have you'd have a better idea.......

Would Mills Fleet or Napa have high temp silicone?

thanks for all the advise I think I'll have the carbs cleaned (again) and air intake adjusted I really don't want a melt down, this is my new baby and I've learned my lesson in the past with two other sleds this one gets all the necessary care.

thx MR

[Meat-Run]

JosMN to repond to your low end comment it does have a slight hesitation out of the hole so I think your right but mid-range it does have noticable power.

mr

[JosMN]

Yep, I'm pretty sure you have 39mm Keihins in that sled. These carbs can be a pain to tune at times, but once you have them spot on, the performance on the low end is very noticable. The mid range on the 600/700 polaris non ves motors has always been great. There are many things that you can do to clean up that hesitation - boostbottle, slp power backs, a lot of different options. I would first clean the pilots really well then start with air screws at 1/4 turn out from seated and adjust 1/8 turn at a time till the stumble isn't there. A slight turn of just the airscrews can fix it. If that doesnt clean it up, drop a set of 40's in for pilots, stock pilots are 38 if I remember right. Another thing is to get a set of the 1371G needles, they help A LOT! Dont worry about burning it down. The pilots only control up to a 1/4 throttle, from there its your mains. I believe when I had my 98, I ran 182 mains, stock I think they were 185s. Some guys stagger the mains too running 182/185. They come fat right from the factory. All this could be totally different from the 2001's, I'm just going by what was in my 98. I ran 40 pilots, airscrew 1/4 turn out and a boostbottle - it took care of the hesitation. That sled was very very quick! Clean that stumble up, and run a different clutchin combo from stock and they will run with anything out there. I dont think I ever lost a race with that 98. 10-64 primary weights (I had the 220 cylinders which ran better with the 64's, you may wan 62's)almond round primary spring, silver blue secondary spring set in #2, two tooth drop on the top sprocket, run a HSP36s, HSP38x, or a polaris R12 helix and hold the F on! I remember those clutching combos from mine like it was yesterday! miss that ol girl! One of the quickest if not the quickest polaris I ever owned.

[JosMN]

and yes, mills or napa will have the gasket sealant. Just be sure to get the highest temp stuff you can find. Here's my ol 98. Sold it in 09 to the first guy that looked at it for $1500, which I thought was a steal! Was stock white for most of its life till my wife tipped it over, cracking the hood a little bit. Just had to fix it! Painted it red, threw on a new set of decals and ended up selling it because my wife was pregnant and didnt ride much anymore. Still wish I had it sitting in my garage, along with my 03 ProX 7.

[Meat-Run]

OK now you're scaring me... j/k sounds like you've tinkered a bit with your carbs, pistons etc. My goal is to have a quick, mean sounding sled without to much aftermarket extras to cause it to melt down (paranoid you can say) because I'm not a wrencher like some but willing to pay for it to make sure it's done correctly.

I'll look into the jets and needls to make sure its "breathing" just right thanks for all your advice and LOVE your pictures of the XC 700 thats a sweet ride.

mr

[JosMN]

Scaring you? haha. I never touched the inner motor, just the carbs and clutching. It was a rock solid sled for as long as I owned it till 5500miles. I know for a fact though, when I put that MBRP can on it, (it was the race can) I did have to turn the air screws in a bit, because it would backfire sometimes. Just clean the pilots, and sync the airscrews and see how you end up - and go from there.