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Discussion Starter #1
Last year I picked up a 2000 XC700. The sled has dual SLP drag pipes, V force reeds and a balance bottle. I spent most of last season dialing in the clutching and suspension, but have always had this bog right after takeoff. Especially In deep powder. Once she gets moving on the pipes she really will get up and go. As long as you keep her singing she will run strong all day. But if you let her drop off the pipes or let the rpms drop too far and try to peg the throttle she wants to sputter and bog a bit before she picks back up. The mikuni round slide carbs that came on this sled from the factory were antiques even when they were new. I am under the impression that they just cannot fuel the engine correctly, and am thinking of installing a set of modern Keihin PWK flat slide carbs instead. Only problem is where to start for a jetting spec. Has anyone done this yet? Pilot and main jets I can sort out as I go,but does anybody have any idea what needle and slide cutaway I should start with? Or any ideas what causes this bog issue.
 

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The Keihin PWK 39mm carbs are the stock ones that came on the sled. You will be looking for Mikuni TM40 rack style carbs. On the wedge chassis, there were a few fitment issues and I had to play with different airbox to carb adapters to find something that would fit. Another thing that will be an issue is oiling. The 700 with the Keihin's oiled to the fuel pump, the 700 with racks oiled to the carbs. So to do it right, consider changing out the 3 outlet oil pump (one outlet to each crank end, one to the fuel pump) to a four outlet oil pump (one to each crank end, one to each carb fitting.)

I had SLP Power Packs and a boost bottle on my 700 with the keihins and also put V-force 3 reeds on it. That pretty much eliminated the burble. I had converted to the Mikunis but the steering column on my 97 700 RMK interfered with the water trap on one of the carbs and sometimes if I hit a bump hard, the steering column would whack the carb and dislodge it from the carb to engine adapter. I went back to the Keihins.

You can get V-Force III reeds (or Boyesen, they are good, too) for that engine, but I don't think SLP sells the power packs any more.
 

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You can still get the boost bottles used a few places. I bought 2 sets of them last year for 40 bucks total for a pair of friends. The power packs are also out there used, just have to watch eBay all the time, same for the boost bottles. Salvage yards also pull both of those as well as they know people want them.
 

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Discussion Starter #4
I bought the sled from a local for what I though was a good deal. The sled is papered as a 2000 XC700. It has been extended out to a 136" track. It's a gen 2 chassis. It came with the dual SLP pipes and V force reeds. It also came with the mikuni round slide carbs on it. I do not know who put them on this sled. The engine has 140 142 psi compression. I do know that the engine has been replaced as I have the old one, it siezed a crank. All and all I really like the sled, it runs strong, just not very cleanly. I will say that this sled will run right over the top of my brothers Mountain Maxx. I like the keihin pwk carbs and run them on my bikes. But if a pair of mikuni rack style carbs would be a better/simpler option then I will probably go for it.
 

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With the Mikuni round slides, there's no data for you to look at, as Polaris never used the VM carbs on the 700 Liberty. So jetting size, slide cut-away, pilot jet size, needle jet and jet needle sizes would all have to be tested, which can get pretty frustrating, not to mention spendy in the search to find the right setup. Polaris did use the Mikuni TM40 rack style in the 2001 engine, so you have a good starting point for testing.

Are the pipes wrapped? Sometimes keeping the heat in the pipe will be really beneficial when engine load decreases.
 

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Discussion Starter #6
Good information to have. I was under the impression that the VM 38s on it were the stock units. It makes a lot of sense to me now. I have literally boxes and boxes of just about every jet made for mikuni, keihin, bing, delorto and Amal carbs from years of racing motorcycles. I spent more time than I want to admit to myself playing with jetting, trying to figure this out, and always came up with the same results. Think I might start hunting down a set of those TM40 rack carbs and a 4 port oil pump. What other machines would have this setup?
 

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any of the Edge big blocks (700 & 800) from 2002 to 2005

I may have a TM 40 set up for my 2001 700 engine somewhere in a box... I know I used the oil pump I had on a broke Edge 800. Let me know if you're interested, I'll try to find it.
 
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