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Discussion Starter · #1 ·
Back again…. I’ve resolved many issues with my Polaris ATP330 and think I’m in the home stretch but not quite sure what’s the issue.

The carb has been cleaned and blown out - all ports / jets / needles.

The machine ran great when I took it for a spin- upon returning home I realized the engine speed rpm wasn’t returning to idle and wouldn’t idle down without shutting the engine off and restarting. Again, when restarting the unit it idles fine till you use the throttle a bit.

I removed the cover off the side of the carb so I could monitor the throttle linkage and carburetor operation. In addition to removing the cover off the right handle throttle kill switch.
The linkage appears to operate smoothly and the linkage and carburetor appear to return back to their original position and with the carburetor returning to the position of resting back on the low idle screw yet the idle rpm doesn’t return to low idle rpm 😳??? Wtf gives ?
 

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Sounds like the idle fuel/air screw is not properly adjusted or perhaps a vacuum leak.
 

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Discussion Starter · #3 ·
Sounds like the idle fuel/air screw is not properly adjusted or perhaps a vacuum leak.
Hey Latebird - thanks again for the reply and all the help so far - you clearly know your stuff from all the forums I see with your comments.

My user manual is an all in one manual covering 1998-2007 and don’t see exactly the ATP 330 - the closest I see in reference is the 2004 magnum 330 which says the pilot screw setting is to be 2 turns out from seated - is this the idle fuel /air screw you mention ? I did recently replace the cylinder head boot that mounts to the carb as the old one was very hard and I didn’t know how well it was sealing on the carb. I’ll check for vacuum leaks there as well.
 

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Yes - the the fuel.air screw, the idle/air screw are all 'pilot screws', however a fuel screw adjusts opposite of an air screw. An air screw is typically on the inlet end of the carb and a fuel screw is typically on the outlet side of the carb. An air screw controls the amount of air being mixed with the fuel metered by the pilot jet in the float bowl that is entering the air stream downstream of the throttle butterfly. A fuel screw adjusts the amount of fuel and air mixture allowed into the air stream while the amount of air and fuel is set by the size of the pilot jet and the size of the pilot air passage drilled into carb body or by an 'air' jet screwed into that passage.

Now in the case of the BS carb the 04 ATP - the pilot air passage is inside the carburetor under the vacuum diaphragm. #40 is the jet that controls the amount of air allowed to be mixed with the amount of fuel that jet #26 allows into the internal 'mixing chamber' - the pilot screw is not depicted as it was capped during manufacturer and is not accessible by the consumer.
Font Art Line art Ink Handwriting


Now the INITIAL pilot screw setting is published in the service manual at 2 turns from lightly seated.
Font Material property Screenshot Parallel Document


Now the pilot screw is depicted in the service manual (parts #28, 29, 30 and 31)
Font Parallel Art Diagram Drawing


Proper setting of the screw is performed after the vehicle has been run for about 15 minutes - an accurate tachometer is connected and the fuel screw is adjusted inward from the initial setting in 1/8 turn increments pausing 3 to 5 seconds between adjustments - when the engine RPM drops by 50, the pilot screw is adjust out 1 full turn from the point the RPM dropped and adjustment is complete.

This all assumes you are using fresh 87 octane non ethanol fuel and the fuel has no additional over the counter additives added to it.

In the home workshop; using 89 octane fuel that is diluted with alcohol - an air filter that is less than new which may not be clean or is freshly cleaned and either over or under oiled and a spark plug that has more than 1 hour of run time on it - you adjust the fuel screw in until you hear the engine start to struggle to idle, then you back the fuel screw out until the idle becomes smooth and not labored - from this point the pilot screw should be turned out 1/4 to 1/2 turn more. The throttle is blipped a few times to assure return to the desired idle speed and if the idle speed increases from where it was previously set, the carb has a problem and it needs to be serviced and the defective or worn parts replaced - if the idle speed drops, labors and recovers to the desired setting, the pilot screw should be turned in 1/4 to 1/2 turn and the throttle blipped again. If a linear return to idle is achieved, your are done - if not, re-service the carb.

Sorry about the slow reply - my son called needing advice on a Dodge truck and another guy called needing Harley parts distracting me from answering.
 

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Discussion Starter · #5 ·
Thanks again Latebird - think this will put me in the right direction. I just need to get motivated to go tinker in the garage in single digit weather - doesn’t sound like much fun 🙄
 

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Discussion Starter · #6 ·
Yes - the the fuel.air screw, the idle/air screw are all 'pilot screws', however a fuel screw adjusts opposite of an air screw. An air screw is typically on the inlet end of the carb and a fuel screw is typically on the outlet side of the carb. An air screw controls the amount of air being mixed with the fuel metered by the pilot jet in the float bowl that is entering the air stream downstream of the throttle butterfly. A fuel screw adjusts the amount of fuel and air mixture allowed into the air stream while the amount of air and fuel is set by the size of the pilot jet and the size of the pilot air passage drilled into carb body or by an 'air' jet screwed into that passage.

Now in the case of the BS carb the 04 ATP - the pilot air passage is inside the carburetor under the vacuum diaphragm. #40 is the jet that controls the amount of air allowed to be mixed with the amount of fuel that jet #26 allows into the internal 'mixing chamber' - the pilot screw is not depicted as it was capped during manufacturer and is not accessible by the consumer.
View attachment 161646

Now the INITIAL pilot screw setting is published in the service manual at 2 turns from lightly seated.
View attachment 161647

Now the pilot screw is depicted in the service manual (parts #28, 29, 30 and 31)
View attachment 161648

Proper setting of the screw is performed after the vehicle has been run for about 15 minutes - an accurate tachometer is connected and the fuel screw is adjusted inward from the initial setting in 1/8 turn increments pausing 3 to 5 seconds between adjustments - when the engine RPM drops by 50, the pilot screw is adjust out 1 full turn from the point the RPM dropped and adjustment is complete.

This all assumes you are using fresh 87 octane non ethanol fuel and the fuel has no additional over the counter additives added to it.

In the home workshop; using 89 octane fuel that is diluted with alcohol - an air filter that is less than new which may not be clean or is freshly cleaned and either over or under oiled and a spark plug that has more than 1 hour of run time on it - you adjust the fuel screw in until you hear the engine start to struggle to idle, then you back the fuel screw out until the idle becomes smooth and not labored - from this point the pilot screw should be turned out 1/4 to 1/2 turn more. The throttle is blipped a few times to assure return to the desired idle speed and if the idle speed increases from where it was previously set, the carb has a problem and it needs to be serviced and the defective or worn parts replaced - if the idle speed drops, labors and recovers to the desired setting, the pilot screw should be turned in 1/4 to 1/2 turn and the throttle blipped again. If a linear return to idle is achieved, your are done - if not, re-service the carb.

Sorry about the slow reply - my son called needing advice on a Dodge truck and another guy called needing Harley parts distracting me from answering.
Hey Latebird - I finally got some time to do more investigation on try Atv.
Being that this issue with the rpm not returning to idle speed - I started to look for vacuum leaks as you mentioned, I had just replaced the boot that mounts to the carburetor and intake. I sprayed some starting fluid around the boot and fittings and did notice a change in rpm as it definitely affected the rpm and raised it up whenever I would hit the sealing face on the boot to the intake.

I didn’t buy OEM for the boot and bought some China crap for a fraction the cost. I don’t see that there is any gasket between the boot and the intake. Do you recommend using any sort of permatex or anything on the sealing surface? I haven’t done the air fuel screw procedure you gave me yet as I’m just getting back around to tinkering after being down with Covid for a bit.
 

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What a wuss - I've had COVID 3 times and never missed a day of work - never had any symptoms either - I had COVID-19, Delta and Omicron - never got the recommended immunity shot, am not going to get the shot - if someone unleashes a strain I'm suseptible to, then I will seek treatment and possibly die, but it's what the doctors who are engineering this shit want. They are making it to make people die, not to feel better.

The carb holder is not designed for a gasket, but if the cheapie is leaking, you need to get it sealed - use some Permatex Motoseal Gasket Maker (item number 29132 - UPC number 686226291325) available at most auto supply stores or use Kawasaki Bond, Honda Bond, Yamabond or Three Bond 1184 - apply it, assemble, wait 24 hours and it should be good for a long time an if a little is good, a lot is not, apply a bead of the sealant to the engine, install the holder and tighten finger tight, wait 24 hours and finish tightening the holder prior to installing the carb - see how that works out - if no success, the sealant can be removed with lacquer thinner, a rag and some elbow grease - an OEM holder is part number 3087050 @ $71 from Polaris or if you order from a discount online OEM supplier about $57 including shipping.
 

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Discussion Starter · #8 ·
What a wuss - I've had COVID 3 times and never missed a day of work - never had any symptoms either - I had COVID-19, Delta and Omicron - never got the recommended immunity shot, am not going to get the shot - if someone unleashes a strain I'm suseptible to, then I will seek treatment and possibly die, but it's what the doctors who are engineering this shit want. They are making it to make people die, not to feel better.

The carb holder is not designed for a gasket, but if the cheapie is leaking, you need to get it sealed - use some Permatex Motoseal Gasket Maker (item number 29132 - UPC number 686226291325) available at most auto supply stores or use Kawasaki Bond, Honda Bond, Yamabond or Three Bond 1184 - apply it, assemble, wait 24 hours and it should be good for a long time an if a little is good, a lot is not, apply a bead of the sealant to the engine, install the holder and tighten finger tight, wait 24 hours and finish tightening the holder prior to installing the carb - see how that works out - if no success, the sealant can be removed with lacquer thinner, a rag and some elbow grease - an OEM holder is part number 3087050 @ $71 from Polaris or if you order from a discount online OEM supplier about $57 including shipping.
Well this is round two for me with the ole China flu lol - not vaccinated and don’t plant to get that shot either as I’m along the same thoughts as you 👍🏼 Although this time around s knocking me down a bit harder than last.

Maybe I’ll just buy am OEM boot - it’s hard to say exactly where it’s leaking but it’s definitely revving up with a shot of either. Just ever god damn OEM part is so costly and this thing was such a mess I need to draw a line in the sand somewhere on what to replace and what not to.
 

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Don't focus on the cost - focus on the enjoyment of a job well done and the fun you can have using it once it's right and dependable. Take 4 aspirin or ibuprofen, drink or eat some chicken noodle soup (my wife drinks it and I put enough saltine crackers in it I can eat it with a spoon) and don't let the Covid kick your ass - go to the doctor and ask for some hydroxy cloroquin or ivermectin. They can treat the bug, but there is some sort of conspiracy not to, but if you are the Prsident or a member of congress there is no problem getting treatment.
 

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Discussion Starter · #10 ·
Don't focus on the cost - focus on the enjoyment of a job well done and the fun you can have using it once it's right and dependable. Take 4 aspirin or ibuprofen, drink or eat some chicken noodle soup (my wife drinks it and I put enough saltine crackers in it I can eat it with a spoon) and don't let the Covid kick your ass - go to the doctor and ask for some hydroxy cloroquin or ivermectin. They can treat the bug, but there is some sort of conspiracy not to, but if you are the Prsident or a member of congress there is no problem getting treatment.
I’ll keep ya posted on my updates - thanks again for the info - you sound like a good shit !
 
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