This AM while loading the ATV onto the trailer for a trip I noticed the odor of gasoline. I started looking around and noticed that the very bottom of the carb was wet and an occasional drip from it to the cylinder. After riding the ATV around checking trailcams and loading back on the trailer the drip had slowed considerably and was nearly non existent. When I got home I pulled it into the garage, took the sides off and wiped as much dirt as I could from the bottom of the carb hoping to locate the leak. While sitting apart in the garage and running I could not get it to drip and it was just barely wet. Problem is I cannot find the source. I am now wondering if this is only happening when the engine is cold, maybe the heat somehow stops the leak?
Here is a photo of the bottom of the carb from the left side of the machine. The little tip protruding from the bottom of the carb is where it is dripping from. The horizontal screw did have quite a bit of buildup of dirt & grease and that buildup was kinda damp around it so I am wondering if this is the source? I am guessing that horizontal screw is a float adjustment screw?

Any one have any ideas on this fuel leak?



Just curious, what is the vertical adjustment screw for?

 

Make sure the fuel bowl drain screw is tight.Missing the drain/overflow line from the fuel bowl.The Bst34 was the best carb Polaris used imo unlike the finicky Bst 40 on later HO models that constantly dripped.About the only time the Bst34 leaked was when a needle and seat was worn/sticking or float level was off. Could be just a temporary thing while loading,float sticking,etc,but if it continues leaking I'd order a carb kit and add an over flow/drain line on the carb bowl past the bash plate so it wouldn't get gas on the engine if it ever leaked again. Float assembly should be parallel with the carb body(13mm or 0.51) when held at a 45 degree angle with the float arm barely touching the needle plunger.Dirt Cheap Yamaha, Honda & Polaris OEM Parts & Accessories – Cycle Parts Warehouse
http://www.ebay.com/itm/NEW-POLARIS-CARB-CARBURETOR-REPAIR-KIT-SPORTSMAN-500-1999-2000-99-00-CARBIE-/171434253681?pt=Motors_ATV_Parts_Accessories&hash=item27ea471d71&vxp=mtr

 

OPT,
As always, your expertise and replies are so very appreciated and I would be up the creek without a paddle were it not for your help!!
Just to make sure I am understanding you...
The small diameter tip protruding from the bottom that I am seeing the fuel is actually a fuel drain / overflow and it is supposed to have a line attached to it to direct fuel down?
The horizontal screw is a fuel bowl drain screw?

 

Correct on the overflow/drain tube and drain screw.

 

Thanks OPT, I'm on it like a dog on a root!
Just curious, what is the vertical screw with the thumb-wheel like head on it in the photo? Idle adjustment or?

 

Idle adjuster.Here's a good link to a service manual if you don't have one. Can answer may of your questions on the carb along with other service/repair issues.http://gh-ftp.com/ORV%20Manuals/Pola...0%20-%20SM.pdf

 

THANKS for the link OPT! I did not have a manual so this will really be helpful.

 

UPDATE
This afternoon I changed the fuel filter and checked the bowl drain screw and it was tight, I could not budge it one way or the other with a fair amount of torque applied.
I then fired it up and watched the drain for signs of fuel and nothing. While it was still running I grabbed ahold of the handle grip and gave the ATV a good shake back and forth and WALLAH, a small amount of fuel would appear at the tip of the drain but when I quit shaking it the fuel would pull back into the drain tube. I then shook the ATV long enough that the fuel did drip out. Shut it off and repeated with the same results except the fuel did not pull back into the drain tube.

What's your thoughts on this?
Will it be OK or do I have a problem that needs to be addressed?

 

All it could take is for the float needle to occasionally stick from varnish build up or needle and seat wear to where too much fuel enters either past the needle or the o-ring around the seat, black specs of of rubber fuel line eaten up by ethanol fuel floating around causing problems,the float setting slightly off,etc to cause this. You can take the carb off and try cleaning as many do,but if you don't install a new carb kit or at least a needle and seat you may still have problems.I hated doing things twice! Just pull the carb,clean it,install the carb kit(cheaper for the kit than just an oem needle and seat) and check float level.Should solve the intermittent leaking.Plus don't over look a worn/wobbly float assy or a worn float pin(not included in the kit) that most people over look. The float and pin take as much wear as the needle and seat.

 

Good morning and THANKS OPT for your help!
Must confess I was a bit overwhelmed thinking about tinkering with the carb and float...been a minute since I last did any work like that. I slept on it and this morning I awoke feeling good about the project. I am going to call my local dealer and discuss the prospect of backup plan if I fail on my attempt at a repair. I will keep you in the loop of my progress.

On a side note, a couple of weeks ago I put some fuel / carb cleaner mix in the tank and now I am wondering if this is now the source of my woes?
Oh well, on the bright side of things I have been really fortunate, this is the most work I have had to put into the machine in all of the 14 years I have owned it!