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Discussion Starter #1 (Edited)
I have a 91 ext 530. I was wondering what are the specs for the air screw. In a search I find any where from 3/4 to 1 1/2 turns out. What is the arctic cat spec for it.

I also have a 91 ext special with the 550. I am wondering the same thing for it. Air screw spec. The 550 has a small bog if you go wot from take off. If I feather it some get the rpms around 2500 then it fine. Just stumbles some coming off the idle. I have sprayed carb clean on the seals to check for leaks and I have not found any. I also put new jets in it. so they should be good and clean. I can also flip the choke up for a quick second or 2 and then the bog will go away too.
 

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1991 el tigre ext
vm 38
main 310
pilot 30
needle jet Q-0 (480)
jet needle 6dh8-4
air screw 1 1/2 turns out

1991 ext special
vm 38
main 310
pilot 35
needle jet p-2 (480)
jet needle 6dh8-3
air screw 1 turn out
 

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Discussion Starter #3
on the 91 special arctic parts diagram calls for a 290 on the main jet. pilot 35. I am 1 turn out on air screw. What else would cause a low rpm bog?? Should I try 1 1/2 turns out on the air screw??

Clutches have been rebuilt and the suspension has been gone through. jack shaft and drive shaft bearings have been replaced. belt is good. Everything I have done to it was to stock settings.
 

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my info came from the arctic performance manual. and the main jet sizes are for break in. I would guess that the 290 main would be a better choice. the factory jets are usually way too rich. if your plugs are nice and brown and not black and sooty then you probably carbed ok you said that your problem goes away with a little choke application. so turning the air screws in would be your best bet. the air screw gets a richer mixture as it is turned clockwise. and leaner if you turn it counterclockwise.
 

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Discussion Starter #5 (Edited)
That make since. I want to richen it up some. Since applying the choke richen it up some and helps. If turning the air screw in doesn't help much. would a size up on the pilot jet help?

Just wondering does that manual give a wide open throttle rpm? It only hits about 7300-7500 mark? One shop I talked says that's right for that motor and another said 8200. The weights and spring are according stock. Weight 0646-102 50.5 spring 0646-083 red/white with a new spider. secondary 0648-12 blue middle hole

The plugs I took out where black and the clutch side was fouled some. But it cleaned itself out after about mile. I did however put some new plug in. Now both sides are contributing at idle. The bog is better but still present. Other then easy on throttle to start out. It runs pretty good.

I suppose since this sled get ridden about 50 to 100 miles per year doesn't help much..
 

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yeah if you have to turn the air screw in too much you should probably go up one size on the pilot. As for the rpm the 550 ext should be about 8000 on the top. maybe a few more for the 550 special. I am not sure about the 530 but between 7500 and 8000 would seem right to me. my 88 tiger 6000 runs at about 8200. and my 89 ext is close to 8000 rpm.
 

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Discussion Starter #7 (Edited)
Just to give you an update. I have the air screws out 1/2 turn now the bog is pretty much gone. Now I have a slight idle hang. Which I am ok with. I think when I have the carbs off next fall to clean. I will go up one on the pilot. Try 1 turn out. I was looking at the jetting chart 290 for 2000ft. at -7. Since I live in Iowa I am thinking maybe 310 would be better on the main.

I also did a little research. On the primary spring The 0646-084 red white is a 92lbs and 222lb. I had a gold Polaris spring which is 100lb and 275lbs. So I put the gold spring in. Now I get a 7500 rpms with an over rev to about 8000. Its has little more get up now.

the 530 runs about 8000. It also runs very well. has about 6500 miles on it. I been wondering if I should do a top end on it. The compression is about 130psi.

The 550 is kinda doggy com paired to the 530. turns about 7500-8000 now.

The thing I find weird is the 530 uses the 0646-083 red/white spring. with 0646-105 weights 50.5 too.

Same grams same spring but the 530 turn 8000 and the 550 7200. Also clutch engagement is 3500 on the 530. and 4200 on the 550. Must be something due to the shape of the weight???

Thanks for the info. and help.
 
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