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Discussion Starter · #1 ·
I've got a 2004 Polaris 90 I got cheap and am trying to rehabilitate for my kids. When I first got it, it would only run with the choke on. I pulled the spark plug which was black but in surprisingly good shape. The air filter was also in pretty good shape. Pulled the carb and it looks brand new. Cleaned it out anyway, made sure the jets were clear, etc., Put on a new fuel line between the petcock and tank, and the gas seems to flow freely.

Put everything back together, kicked it over, and it started right up without the choke on. Started to give it gas and it died immediately. Started it again and it idled ok, but died when I tried to give it gas.

Adjusted the air screw (so many times I forget which setting I was on) and got it to where the engine would idle, and I could apply gas and take off. Under heavy throttle it was bogging down (too lean or too rich I can't tell), but when I brought it back to idle it would die.

Tried adjusting the throttle slide stop screw and nothing really happened, except once or twice when a slight adjustment coincided with the engine dying.

Starting to chase my tail here. I'd really appreciate any insight as would my kids!
 

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Discussion Starter · #3 ·
That's a good idea. I had a similar problem with an XR70 and pretty much solved it by removing the flame arrestor. The Predator 90 doesn't appear to have a flame arrestor though. Should I just pull the entire exhaust and see if it is clogged?
 

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Discussion Starter · #5 ·
That doesn't appear to be the problem either. I pulled the exhaust and it does the same thing - won't idle, can keep it running with throttle - but louder.

Could it be as simple as the air screw/idle speed adjustments? As I mentioned the idle speed set screw doesn't appear to do anything, so might look at where the throttle cable attaches to the carb.
 

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Discussion Starter · #7 ·
Good question I will double check the needle.

In the meantime, I have gotten it to idle more or less indefinitely without the choke, so that is progress. It still bogs down under acceleration, feels like the power is way off at full throttle, and it dies if you drop it back to idle quickly. And it has dark smoke which it didn't before.
 

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Discussion Starter · #9 ·
I don't know how to tell if they are the proper size or not. I was told the carb is almost new, and it looks like it. No buildup or discoloration. I pulled the jets and blew carb cleaner through them and they look basically new. Of course that doesn't mean it is the right new carb. The frustrating part is everything I think of to try that has fixed other bikes with similar problems seems to be ok. Plug doesn't look bad, air filter isn't bad, carb isn't gunked up, exhaust flows freely.....
 

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pilot jet is very small. you should have hard time to see light through it.

look through both pilot and main and try and see light. should be a big difference. if same, buy new jets.

seen people put torch cleaners and drill bits in them to clean.....overboring them. only soft, brass.
 

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Discussion Starter · #11 ·
The jets are fine. Originally the atv would only run with the choke on, so the first thing I did was clean the carb and make sure the jets were clear. The carb basically looks brand new inside and out.
 

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Discussion Starter · #12 ·
Aknawful, thanks for all your help! Knock on wood I think I stumbled across the setup that works. After taking everything apart and cleaning it, I set the air screw to 1 1/4 turns out and it runs strong from idle to WOT. I'll see if it will maintain that performance but so far so good. Appreciate it!
 

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Had the same problem with our 90 a few weeks ago, a switch up on the handlebars where the throttle is. It was stuck, i should probably replace it, but after freeing it up it works fine


Sent from my iPhone using Tapatalk
 

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Also check the intake boot between the Carb and Cylinder for any leaks or cracks and make sure the Airfilter housing is intact with the cover on - these 90s hate to run with the airfilter cover off or the boot damaged
 

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Your issue may be similar, but it is not the same - instead of trying to revive a dead thread, try starting a new one for a better response.
 
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