# Brute pilot air screw o ring?



## lilred (Mar 7, 2012)

I have a 05 brute, that I bought from a friend, and it has only been rode once in a year, so I knew the carbs was gunked up after sitting that long, by the way it was running, it would back fire through the carbs and exhaust, and would stummble at idle to wot, and would run good with choke half way on, I took the carbs off and cleaned them, they really was not that bad, I took all the jets out and pilot screws, when I took at the pilot screw I seen a o ring and a little washer, the o ring looked to have a tear in it, the other carb did not have a washer in it or if it did i lost it? So put it all back together, and it runs great at 3/4 throttle to wot, but from idle to 1/4 or so it is running rich, and backfiring out the exhaust and stummbles bad at that speed, I set the screws at 2.5 turns, do I need to adjust them in more to lean it out, or would the o ring cause this? Yes I'm a noob so be kind...Thanks guys


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## lilred (Mar 7, 2012)

Also I think one reason it was running bad at first is that my choke plunger spring was full of crap..


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## NMKawierider (Apr 11, 2009)

Its also very common to have the choke plungers not seal against the port. If it is truly rich, look there first however it is also very common for the pilot port to plug with dried gas and not re-open with fresh gas. It takes a carb cleaner to break that down. This makes it run lean, pop back through the carbs...run erratic and make a rumbling missfire sound through the pipe. Also very common is for the carb boots to split at the clamp at the heads. This lets raw air in making it run jurky and pop back through the carbs as well.

Yes, make both the carbs A/Fs the same with good O-rings and backing washers. You can buy them on line.


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## lilred (Mar 7, 2012)

I took all jets out and cleaned them with carb cleaner, all looked good.. The main jet the holder that it sits in with the round holes around it, is bottom of it sealed off? Because mine is.. part 13280








The bike runs good at 3/4 to wot, just at low speeds it does have a rumble in the exhaust like a missfire at 1/4 throttal.


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## lilred (Mar 7, 2012)

So with the o ring in the pilot screw being messed up, would that cause my problum?


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## NMKawierider (Apr 11, 2009)

Brute-Power said:


> So with the o ring in the pilot screw being messed up, would that cause my problum?


It can suck some air through making it a tadd leaner. It would have to be getting a lot more in my opinion to make it run like you say. Stick some gum over the screw hole. That will stop the air draw through it. If it fixes it, you have your answer.


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## lilred (Mar 7, 2012)

Well i covered the holes but it changed nothing, I adjusted the screw all the way in on both carbs and it ran the same..It is werid from 1 mph to 10 it is ok but from 11 to 25the it cuts out and stumbles and people riding behind me say it running rich because of the smell of gas.. So what is causing this..


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## NMKawierider (Apr 11, 2009)

Leaking choke plungers.


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## lilred (Mar 7, 2012)

I will check that out next, how do i know if they are leaking? Can i pull them out and cover the hole, just to see if that is it, then i would know where to start?


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## NMKawierider (Apr 11, 2009)

Brute-Power said:


> I will check that out next, how do i know if they are leaking? Can i pull them out and cover the hole, just to see if that is it, then i would know where to start?


No...lol..the plunger has to seal-off a port. Best to inspect them by taking out the retainer screw and slide them and the springs right out. When out work the choke lever to make sure they both work right and clean them up well. Get some spray carb cleaner and flush-out the ports. Check the ends and the seals to make sure they look good. 

Most often the cables rust and makes them hang-up and not close all the way. Might want to lube-up the cables while there.


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## lilred (Mar 7, 2012)

Lol yea i know i would have to seal the hole. Ok i will do this and see if it helps thanks...


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## lilred (Mar 7, 2012)

Update, got my brute running like new, it was the choke plungers hanging open, causing it to run rich, Thanks for all the help...


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