Tm Flat Slide Carb Question

[jtman04401]

Flats on a 2000 ZRT800..

I know the base setting for the "fuel mixture" screw is 1 1/2 turns out from seated.. however the flats also have an "air mixture" screw as well and I cannot find any info on how many turns out this one should be? On the round slide carbs they have a small jet that is very simmilar... I believe they call it a "pilot jet" (or maybe its not the same as the pilot jet?) I cannot find any info on how to adjust this screw.. what the setting should be. A friend of mine says on the TM series flats this air screw works just the backwards of the pilot jet on the rounds. I know on the rounds the more you screw it out the richer it is. He says on the flats he believes the more you screw it out the leaner it gets.. ??

Any help on this would be nice.

Thanx.

[fast426]

The more out you go the leaner it gets, this is correct. Put it about 1-1/4 out and try that, adjust as needed.

[jtman04401]

The more out you go the leaner it gets, this is correct. Put it about 1-1/4 out and try that, adjust as needed.
[/b]

Affirmative... I will take a look at it. Its not running poorly.. I just wanted to see if it was at factory setting or if the previous owner had played with it at all.


Thanx.

[bjankuski]

The more out you go the leaner it gets, this is correct. Put it about 1-1/4 out and try that, adjust as needed.
[/b]

Guys, this statement is not correct. On flatslide carbs ™ the air mixture screw adds more fuel the farther out you turn it. The stock setting on the ZRT 800 is 1-1/2 turns out. Do not go more then 3 turns out from the seated position. On a typical (VM) carb the air screw gets richer the more you turn it in. The ™ fuel screw actually controls amount of fuel flow. On the (VM) carbs the screw is called an air screw and it controls air flow. The farther you turn it in the less air flows and it gets richer at idle.

[MUSKOKA800]

Guys, this statement is not correct. On flatslide carbs ™ the air mixture screw adds more fuel the farther out you turn it. The stock setting on the ZRT 800 is 1-1/2 turns out. Do not go more then 3 turns out from the seated position. On a typical (VM) carb the air screw gets richer the more you turn it in. The ™ fuel screw actually controls amount of fuel flow. On the (VM) carbs the screw is called an air screw and it controls air flow. The farther you turn it in the less air flows and it gets richer at idle.
[/b]

Both statements are true to some degree.
Turning out (opening) the air screws does add more air, but air is required to pull the fuel through it's circuit. If your sled high idles and will not settle down and openning the fuel screws doesn't help then open the air screws slightly. The advise came from GLS at AC when I was struggling with a idle hang-up on my ZR800.

[jtman04401]

Guys, this statement is not correct. On flatslide carbs ™ the air mixture screw adds more fuel the farther out you turn it. The stock setting on the ZRT 800 is 1-1/2 turns out. Do not go more then 3 turns out from the seated position. On a typical (VM) carb the air screw gets richer the more you turn it in. The ™ fuel screw actually controls amount of fuel flow. On the (VM) carbs the screw is called an air screw and it controls air flow. The farther you turn it in the less air flows and it gets richer at idle.
[/b]

Now you have me completely confused... lol. The fuel mixture screw... the one with the white knobs on it should be at 1 1/2 out from seated.. that I know is the base setting. I am referring to the smaller screw that is on the larger side bell of the carb.. the one that looks like a pilot jet that is on reg round slide carbs. This is the one I am currious about. It was turned out a lil over 2 full turns and I believe that is a b it much so I wanted to go with the factory settings and start from there.

?? should those screws be out 1 1/4 or 1 1/2 ? or???

[fast426]

If I turn my screws in the EGT's at idle go down, and out they go up, Richer and leaner respectivly. If I am wrong on this I would love to know. Either way 1-1/4 or 1-1/2 you are not going to notice any real difference. If you are not fouling plugs at idle or any bad runnign conditions (note this screw really only affects idle condition) I wouldn't mess with it.

[FeelTheThunder]

I asked the same question a long time ago and nobody seems to have the answer. Even the service manual dosen't tell you. Somebody even told me I don't have air screws.

Here's what I know. Turning the air screw out leans the mixture (adds more air). Turning the fuel/mixture screw out adds more fuel/air mixture to the engine at idle and off idle. If the fuel/mixture is too much volume the sled will load up and possibly idle too high at times.

Opening the fuel/mixture screw does not richen the mixture, it just adds more of it. I believe the fuel/mixture gets air from the air screw and fuel from the pilot jet but I always have a hard time following the fuel flow in carbs.

I have included a picture in case someone wants to tell me I have no air screw.

Flatslide carbs are famous for high idle problems although I never had those problems until I got about 3000 miles on my T-Cat. My wifes 99 ZR700 (twin) with 40mm flatslides idles like a charm everytime, never a high idle. :dazed: :dazed: