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Hello friends I read a lot on here but do not post much.


I have a 1990 Artic Cat that no matter what I do it is maxed rpm. As soon as I start this thing it just goes to max rpm. I turn all the screws in all the way made shire the slides were not stuck. More or less trying to stop the flow of gas No matter were or how I adjust anything it dont seem to make any difference. I just cant figure out what is going on. I can not find anywhere that it would have a vacuum leak but it is somehow.

ANYONE GOT ANY IDEAS
 

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So did you take the carbs off and go through everything? What is "Max RPM", what rpm? If your carbs are shut your trying to say you have two 34, millimeter leaks? Sorta need more information; Like what 1990 Arctic Cat?
 

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well yes I did clean the carbs, after doing that it did not make any difference. The motor is a 1990 artic cat cougar 500cc. The sled had the factory extended track I think its the longest one they had.
As of today I have put on the carbs that were cleaned from a 95 97 artic cat 440 lc. not exactly sure of yr cause i purchased it without the title but it does have the electric safety things on the side of the carb that I read do not matter if there hooked up or not. Since I have done this it now has to be started with starting fluid and starts at 3k plus rpm and has way more throttle response above 3k but will not run after you let the rpms go down. It dont seem to help when adjustments are made to carbs does make the normal adjustments. Starts right up with starting fluid and runs unbelievable at high revs but will not idle at all. With the newer carbs on it went from the bogey throttle response like the older sled and now runs like its a brand new motor and the response is like a electric motor now. Instant throttle response. Kick ass but will not idle down. Did I read a incorrect response about the electric thing not needing to be hooked up. Or am I missing something. One difference with these carbs is I am not using the oil injection i am just mixing it with the fuel and plugged the lines from the injection. The carb mounts are a little closer to the block now without the injection plate.
If anyone can give any help it will be greatly appreciated. For today i am going to mess with the new carbs and if I cant figure out anything I am going to go through the old ones and try them again. Wish me luck. Pics are the sled carbs are from
 

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I take it the newer carbs are the same size? Does it continually rev high even after warmed up? Have you adjusted carbs to those specs such as air/fuel, throttle, and choke cable? Jet size? Needle placement?
 

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Carbs cleaned and set and rebuilt properly, new rubber carb boots throttle cables set correctly all set to factory spec per the manual, should start without either and idle just fine, without doing one of those things your missing something I'd go back and look at the factory carbs that came with the sled, it ran fine when it left the showroom
 

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well yes I did clean the carbs, after doing that it did not make any difference. The motor is a 1990 artic cat cougar 500cc. The sled had the factory extended track I think its the longest one they had.
As of today I have put on the carbs that were cleaned from a 95 97 artic cat 440 lc. not exactly sure of yr cause i purchased it without the title but it does have the electric safety things on the side of the carb that I read do not matter if there hooked up or not. Since I have done this it now has to be started with starting fluid and starts at 3k plus rpm and has way more throttle response above 3k but will not run after you let the rpms go down. It dont seem to help when adjustments are made to carbs does make the normal adjustments. Starts right up with starting fluid and runs unbelievable at high revs but will not idle at all. With the newer carbs on it went from the bogey throttle response like the older sled and now runs like its a brand new motor and the response is like a electric motor now. Instant throttle response. Kick ass but will not idle down. Did I read a incorrect response about the electric thing not needing to be hooked up. Or am I missing something. One difference with these carbs is I am not using the oil injection i am just mixing it with the fuel and plugged the lines from the injection. The carb mounts are a little closer to the block now without the injection plate.
If anyone can give any help it will be greatly appreciated. For today i am going to mess with the new carbs and if I cant figure out anything I am going to go through the old ones and try them again. Wish me luck. Pics are the sled carbs are from
Ok, what did you utilize to “clean carbs” with?

As pointed out above, are settings correct?

Are choke cables set correctly (1/16” - 1/8” slack at lever when lifting lightly USING just your finger and thumb AT the steel pressed in roll pin)?? Using just enough pull to see if there’s MORE RESISTANCE than slack (more resistance would be stiff springs at plungers beginning to restrict movement), lighter resistance is from spring inside of choke control box behind lever itself.

As mentioned above, it should at least stay running, provided the slides have at least 1/8” under slides when resting on the idle screws.

Check the above (slack setting) and slide resting height (by sliding a 1/8” drill bit under slides, and adjusting screws until contact is made), then start and see how it runs. << THOSE slide height are just quick reference “base settings” that’ll help diagnose an air leak, by having a Mikuni VM series carb “closer” to OEM idle settings “quickly”
 

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Sorry for the delay in my reply. I ended up cleaning the origional carbs and put them back on, Thyere was a big difference from before, now the motor runs totally different and noe making adjustments makes a difference. I have them set so it runs and isles great. still have some fine adjustments to get better performance in the higher rpm range.
Thanks to everyone for any responses made. Definitely learned a few things
I have another question...
This is s air cooled engine that I stuffed into a small buggy. Tomberline crossfire 150.
What are people doing for a temp gauge. What and were do I want to put it so I get the best temp reading. I am planing on just using a temp gauge and putting the sensor on the block somewhere. It least it can tell me before I let the thing get to hot and burn it up.
 

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I have another question...
This is s air cooled engine that I stuffed into a small buggy. Tomberline crossfire 150.
What are people doing for a temp gauge. What and were do I want to put it so I get the best temp reading. I am planing on just using a temp gauge and putting the sensor on the block somewhere. It least it can tell me before I let the thing get to hot and burn it up.
Ok what engine, free air? Fan cooled? in the old Free Air days we could get cylinder head hep gauges they had big eyelets you put under the spark plugs, those were the thermocouples. You'll have look around for those , probably vintage by now cause nobody uses them on a fan cooled
 
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