Sorry to be bugging you guys about this again lol. Ok i need to know the set up for the fuel and air screws for a 03 700 rmk? it has a slp boost bottle, slp pipe and can, and slp air box thats gutted. i have 500 jets in there right now and am set for 1000-3000 ft. i have heard many different settings, i heard 1.5 fuel and .75 air, and then i also heard 2-2.5 fuel and .75-1 for air? idk where i should set at, and does the boost bottle, pipe and can, and air box make a difference? thanks
fuel and air screw help!
- Thread starter mitchellsled87
- Start date
Stock setting for a 04 700 RMK is fuel screw 1.75 turns out, and air setting is 1 turn out. I think your 03 would be the same. Yes, the above mods will make a difference on the settings. I would start with stock and adjust small amounts, if you feel it is needed. Out more fuel on fuel screw etc. Hope this helps!
SD
SD
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boxster7614
Well-known member
Just FYI
Carburetor tunning
Air screw is located on back side of carb (small screw)
If turned in will richen the mixture this is a Coarse adjustment
Fuel screw is located in front side of carb (white plastic screw)
if turned in will lean the mixture this is a Fine adjustment
They both adjust the air/fuel mixture they just go about it in different ways. You get it in the ball park with the air screw (coarse adjusment) then dial it in with the fuel screw (fine adjustmnet) You never want to be all the way in or all the way out on the fuel screw you want it somewhere in the middle. Hope that makes sense.
Carburetor tunning
Air screw is located on back side of carb (small screw)
If turned in will richen the mixture this is a Coarse adjustment
Fuel screw is located in front side of carb (white plastic screw)
if turned in will lean the mixture this is a Fine adjustment
They both adjust the air/fuel mixture they just go about it in different ways. You get it in the ball park with the air screw (coarse adjusment) then dial it in with the fuel screw (fine adjustmnet) You never want to be all the way in or all the way out on the fuel screw you want it somewhere in the middle. Hope that makes sense.
Boxster you say get somewhere in the ball park, how do you adjust it to the right spot? by listening to it at idle, or do you have to run it and check the plugs? i have it set right now at 2 for fuel and .75 for air, it seems to idle a just a little bit choppy, so if i go 2.25 fuel and 1 for air, and just adjust it till it seems to idle smooth? i just don't want to screw anything up and burn up the sled lol
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boxster7614
Well-known member
1st make sure your engine is warmed up and put it on a stand or drive it around a bit, you need to let the engine load up. Just run it and get in and out of the throttle. Usually there will be a low end bog if it;s too rich or it won't idle down if its too lean. Once it starts running crisp and clean you got it. Your air/fuel screw really only affects the low end You will check your plugs and piston wash for your main jets. Your needle position and main jets will affect mid and top end. There is also an adjuster screw (metal screw/knob on carb rack) to change idle which basicaly just adjusts the throttle position if you are idling too low.
Ok so by "low end" do you mean low throttle/low rpms? so air/fuel screws affect low end, main jets affect mid and top end which results in burning up your pistons if the main jets are wrong. so, just adjust it till it isn't boggy or won't idle down? thanks a bunch
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boxster7614
Well-known member
Welcome to carbs 101!
I mean low end of the throttle position which translates into low RPMs.
The air/fuel circut along with the pilot jet controls the idle and on up to 1/4 throttle, give or take a bit.
Jet Needle is the needle that rides in the throttle slide and goes into the main jet. This needle controls the fuel mixture from 20% to 80% open throttle. The top end of the needle has grooves cut in it and you can move the little clip on the end up or down to lean (down) or richen (up) the mixture. Look on SLP's web site to see which position to put your clip.
Main Jet controls the fuel mixture from 60% to 100% open throttle.
We want nice clean acceleration from idle to full throttle, with no stumbling or flat spots. SLP's website will get you pretty close on clip position and jets. For 0-3000 they say 45 pilot, #3 clip and 500 mains
You need to adjust your air/fuel screws so it idles and doesn't bog in that first 1/4 throttle. Like I said when you get it right its nice and crisp but when it's too lean many times the RMPs will hang and not idle back down when you come to a stop. If it bogs at mid throttle its your needle clip position and top end will be main jet.
I mean low end of the throttle position which translates into low RPMs.
The air/fuel circut along with the pilot jet controls the idle and on up to 1/4 throttle, give or take a bit.
Jet Needle is the needle that rides in the throttle slide and goes into the main jet. This needle controls the fuel mixture from 20% to 80% open throttle. The top end of the needle has grooves cut in it and you can move the little clip on the end up or down to lean (down) or richen (up) the mixture. Look on SLP's web site to see which position to put your clip.
Main Jet controls the fuel mixture from 60% to 100% open throttle.
We want nice clean acceleration from idle to full throttle, with no stumbling or flat spots. SLP's website will get you pretty close on clip position and jets. For 0-3000 they say 45 pilot, #3 clip and 500 mains
You need to adjust your air/fuel screws so it idles and doesn't bog in that first 1/4 throttle. Like I said when you get it right its nice and crisp but when it's too lean many times the RMPs will hang and not idle back down when you come to a stop. If it bogs at mid throttle its your needle clip position and top end will be main jet.
Hahaha sorry about all the questions, i like to learn new stuff about snowmobiles and how they run lol, i'm glad they have snowest so i can learn all this stuff! thanks a bunch tho i understand it a lot better, cuz carbs have always confused me. Carbs 101 helped alot haha
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likinit2
Member
First, if you are running the setup you say you are too rich.
This is what I would start with but try at your own risk........
470 mains
clip #3 position on needles
fuel screws 2.5 turns out
air screws 1.25 turns out
(be very careful with the fuel screws and air screws. when turning them in all the way be very gentle and use a very small in diameter handled screw driver. If you over tighten on of these and twist the tip of the brass adjustment screw off in the housing you are pretty much done.)
Try this and if it loads up when your out riding after stopping and idling and or running real slow. turn the air screws out another .25 turn at a time until you get it just to the point where it doesn't load up anymore and stop. check plugs and piston wash. Also going to lighter ves springs such as the yellows helps with the slp pipe as the midrange can run a little warm and the sooner you get the valves open is a better situation.
Good luck
This is what I would start with but try at your own risk........
470 mains
clip #3 position on needles
fuel screws 2.5 turns out
air screws 1.25 turns out
(be very careful with the fuel screws and air screws. when turning them in all the way be very gentle and use a very small in diameter handled screw driver. If you over tighten on of these and twist the tip of the brass adjustment screw off in the housing you are pretty much done.)
Try this and if it loads up when your out riding after stopping and idling and or running real slow. turn the air screws out another .25 turn at a time until you get it just to the point where it doesn't load up anymore and stop. check plugs and piston wash. Also going to lighter ves springs such as the yellows helps with the slp pipe as the midrange can run a little warm and the sooner you get the valves open is a better situation.
Good luck
What do you mean by load up? sorry i'm new to the carb situation
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