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Discussion Starter · #1 ·
alright so i bought a slp boost bottle, drilled out three 1/4th holes in the bottom of the snorkel tube, start the sled up and idles high. So i turn the idle speed down. Now its backfiring loud once in a while, and sounds nothing like what it used to... any ideas? the plugs are wet also, but they were before anyways
 

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Usually You need to change the jets or adjust the needle position when you install the boost bottle. Also, High idle is a result of adding a boost bottle. I bought a new boost bottle this summer but decided not to install... I have the directions that came with, but they're back at home. What I just told you is going off memory from reading it, so somebody should verify my statements.
 

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Follow the instructions. It will work.

http://www.slp.cc/instsheets/22-52.pdf
 

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Discussion Starter · #4 ·
so i should turn the air screw in a half turn? i got it idling at the rpm i want, it just runs choppy and doesn't sound as close to as crisp at it did without the bottle..

this thing is friggen confusing haha. i think im just going to shove some spark plugs in those holes and do away with the bottle
 

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What sled are you working on?
 

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You won't have to change any jets or needle position! You will have to adjust the idle down using the cable adjusters probably to get it low enough, the reason for the high idle is because the boost bottle it working, it was rich at idle before thats why it idled up now, it leaned out. You will need to sync the carbs down to about 1600 rpm idle speed and you will most likely have to adjust your mixture screws. Once you get it dialed in you will like the throttle response. 1371g needles are also a good add on to that sled.
 

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so how do you proply adjust the kheins, on the 99 700's, i havnt done mine yet because it was to warm but i am wakin up to some teens and low 20's so i think i can set it without to many worries.
 

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NY98xltsp said:
what is a boost bottle anyway? i have never heard of it and am not quit sure what it is
http://lmgtfy.com/?q=What+does+a+boost+bottle+do%3F

Or, just do a search on this forum. It's only been covered several dozen times.
 

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piece of plastic you stick between the carbs to help "Equalize" them, they seem to make a difference IMO, some people swear by them, some say there a joke, all depends on the sled, and if its adjusted right

if your running all efi's i dont think you can even use them, never tried though
 

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dtmmil,
Pockets told me not to use those needles on the 98 because of the hotter cdi.

When tuning with the boost bottle, you will need to adjust the air screw in to richen to mixture and lower the idle speed.

Here is how I set-up mine for the trails. 195lb. rider, 900'-1000' elevation good for -10* F

#38 pilot jets

6.0 slides (stock XC 7)
(The factory replaced the original 6.5 slides and #45 pilots with 5.5 slides and #38 pilots. I found the 5.5 took too much of the responsiveness away and that the 6.0 slides worked best for me.)

178 mains (for long WOT runs use 182s)

1.5 turns on the air screws
I adjusted these daily with temp changes as the Keihin carbs are very finicky. As little as 1/8 turn makes a big difference.

SLP Power Packs in the carbs (helps low end throttle response)

V-Force reeds (a good improvement on most Polaris big block twin)

Polaris almond/gold primary spring
Polaris 10-60 weights
Polaris R12 helix
HSP orange secondary spring #2 hole

Stock 22/40 gears

Wilwood master cylinder from an AC ZR 600.

3" riser for handle bars

Fox shocks from a 98 XCR 440 all the way around
Unless she really rides hard I wouldn't run the XCR 440 shocks on the skis.

I also moved (re-drilled) the front torque arm mounting holes in the tunnel up 7/8" (closer to the seat) like 99 and newer Gen II sleds. Better attack angle for the track, smoother ride, and flatter cornering.
 

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Discussion Starter · #13 ·
i got one for sale if anyone is interested haha. ok i took the boost bottle off, put spark plugs in the holes and wire tied them in. This thing is a totally different sled, idles up and down, backfires when i crack the throttle and sounds weird still, it was running perfect again and then just randomly stops without me even touching anything and shuts down and backfires. I guess this goes to show not to touch anything when you dont know what your doing haha. Ill have to get a video...ill have to have a friend come over and help me out
 

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Vamped400 said:
i got one for sale if anyone is interested haha. ok i took the boost bottle off, put spark plugs in the holes and wire tied them in. This thing is a totally different sled, idles up and down, backfires when i crack the throttle and sounds weird still, it was running perfect again and then just randomly stops without me even touching anything and shuts down and backfires. I guess this goes to show not to touch anything when you dont know what your doing haha. Ill have to get a video...ill have to have a friend come over and help me out
Are you sure you dont have bad gas? Or sounds like maybe some jets are a bit clogged.
 

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Discussion Starter · #15 ·
it was running 100% perfect before this. When i started up the sled with the boost bottle on it was still running good, just idled high, so i shut it down and idled it down a bit, and thats when it started running bad...
 

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did you remove the boots when drilling? maybe some junk from drilling got stuck somewhere
 

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If you take the time to properly tune the keihin carbs they can be made to run without the bottle, patience and testing is key, the 99 XC 7 here in my garage responds just as good without a bottle as my 98 that has a bottle on it, my angle is that I have 12 years experience with tuning the keihins, the best thing I did for the 99 was to scrap the stock 5.5 slide and put the leaner 6.0's from a 98 in it along with 1371 needles, there is no one set rule of thumb settings for these carbs, I've never played with them on a 600 but never the less the same procedures are going to apply, LOTS of testing and tuning, the topic of tuning these carbs with or without a boost bottle has come up countless times over the years, it took me more than a few years to finally figure them out, while some will say they are junk and should just be replaced with mikuni rack 40's I've never had to resort to that, your best bet now would be to start over at square one with the stock setup and then start making adjustments one at a time until you get it back to where it should be.
 

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Discussion Starter · #18 ·
yeah i took the boots off and made sure nothing was loose that could fall off. i might take the boots off again and fill the holes with silicone. im adjusting the carb by the plastic idle screw on the carb itself if that matters. i have not touched anything else... its weird
 

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tnmemr cool, didn't know that, I was going by my 99 xc6 and 700. And on the xc600 the boost bottle made a hell of a noticeable difference, for us anyway, not so much on the 700, but the 600 was noticeable. If you follow the instructions for the installation you can get it to idle right and run right. When I put the one on my wifes 99xc600 we went for a trail ride that weekend and my wife asked what I had done to her sled, I said just the boost bottle why, she said, it just wants to go! It made a difference on mileage, and throttle response on her sled. I would put it back on and follow the instructions.
 

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You probably have an air leak, zip ties aren't particularly strong holding.
 
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