Polaris ATV Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
4,081 Posts
Discussion Starter #1
Evening guys,
I need to rebuild the carb on the 2001 325cc Polaris Trail Boss.

I believe I have a bad float/miss adjusted float level or most likely a bad needle and or seat. At idle I have fuel dripping from the overflow at the base of the carb. At speed it stops.

Where on line can I get a rebuild kit?

CW
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #2
Anyone know where I can get a rebuilding kit online?

CW
 

·
Registered
Joined
·
2,352 Posts
try manufacturers supply..............i got a complete kit, jets and all for $17. plus freight
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #5
Thanks guys.

I checked manufacturers supply, nothing listed for the 2000/2001 TB... Babbits shows nothing either.

I sent a Email to both so hopefully someone will have something for me.

CW
 

·
Registered
Joined
·
324 Posts
Babbits has all the oem parts, what do you really need for your carb? most the time the only things that can go bad are the bowl seal and the float/needle/seat assembly everything else can usually be cleaned and returned to service. Honestly in the 20+ years I've been working/riding/racing motorcycles and atvs I have only ever replaced one float needle/seat. the biggest replacement item is the bowl seal and it is cheap, and thats only because it sometimes will tear on bowl removal. 99% of problems with mikuni carbs (especially non CV carbs) are related to gas varnish from sitting around. This is easily cleaned by disassembling the carb and cleaning it with carb cleaner an air compressor and some fine nylon brushes (old toothbrush). be sure to blow out and check all the idle ports and jets those are the problem areas. Then remove the float and clean the needle/seat assembly very well with a soft cloth.
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #7
Thanks for the tips!

My problems are poor idle but fine with choke on. Gass coming out the overflo at idle but appears to completely stop at higher RPMs. When riding after running down a hil, it will stumble for a few seconds then clear out.

My guess is needle and/or seat, float and or float level. For the stumbling, and idle I agree with you, maybe one of the air ports.

I believe this is a CV carb. at least some of the litrature reads that this is a 31MM CV carb. Of coarse I could be completely wrong. Im new to ATV's.

CW
 

·
Registered
Joined
·
324 Posts
take the bowl off and remove the idle(low speed) jet. Then blow carb cleaner directly into the hole where the idle jet came from you should see it coome out of a few tiny ports in the engine side of the carb. Immediately after blowing carb cleaner through take an air compressor and blow directly into the same low speed jet hole. You should repeat this a few times each time looking at the flow coming through the ports. Then take your low speed jet and look real close at the openings they should be round and perfectly clear. Take some carb clean and blow through each of the holes in the jet then use the compressor and blow it off (hold onto that thing tight so you don't blow it across your garage... been there done that!!). Most of the time idle problems lie in this jet. Next remove the idle mixture screw and blow through it with carb cleaner and air. When re-assembling it turn it in all the way and then out 1 1/2 turns (don't tighten it too hard!! or it will damage the screw and the seat).The next thing you need to do is remove the float by pulling the pin that slides into the carb body. Be careful when removing this there is a tiny spring clip that holds the needle to the float arm don't lose it. Clean the mating surfaces of the needle and the needle seat. next check your needle to make sure the spring inside it moves freely. If it does not spray it with carb cleaner and work it in and out with your fingers this will usually clean it out and allow it to flex again. Then reinstall the parts and check your float level. Stock setup on most mikuni carbs is the float tab set parallel with the bowl flange. So when you hold the carb upside down your float tab (the brass lever the floats use to close the needle) should be perfectly parallel with the flat surface that the float bowl mates to. if it is not parallel then take a small screw driver and adjust it by bending the brass tab until the float arm is parallel. Now remove the main jet and spray it with carb cleaner, again viewing the hole to make sure it is perfectly clean and round. In the worst cases I use a piece of fine brass or copper wire to run through the holes to clear them out, or just the bristle of your brush. Now finally before you put the bowl back on take your brush and clean out all the gunk that is dried in there. If it is heavily varnished spray it down it carb cleaner and allow it to dry and it will rub right off like a powder. The most important thing is an eye for detail blow through all the small holes that you see and look for the carb cleaner to flow through freely. Not only will it clean your carb it will also give you a good understanding of how this seemingly complex peice of equipment is very basic and easy to understand.
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #9
Thank you very much for the explanation!!!

I have rebuilt a couple Carter and Holley car carburetors, just never a bike carb. I know they are a bit simpler. I didn't realize they where that simple!!

I'll order the bowl seal, pick up a couple cans of carb clean and dive in once it arrives!!! I have a gallon of carb clean as a dunk/soak tank too if I really need to clean any parts.

Thank you again!!

CW
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #10
I still cannot find the exact parts I need, BUT I took a shot tonight with Babbits. I have three choices with what model 2000 Trail Boss I own. Apparently there are three different possibilities......

Good news is they got me for a bunch of Lil things I needed... 100 bucks later I got the gasket, needle and seat I went there to order. ;)

Thanks for the tips guys. Its gonna be at least two weeks. (Looks like SLOW shipping) I'll be sure to post up the results.

CW
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #11
OK guys,
I have this week off from work. SO on my first day off I got right out in the garage and tore into the Trail Boss!!

No problems and about three hours time. I also fixed a hot trigger wire on my recent winch mount, rebuilt my headlight, adjusted the valves and changed plug and fuel filter.
The winch was accidentally hooked to the tail brake light. (oops) and the head light had all its springs removed. I got new bolts and springs in that Babbits order.
The PO installed the completely wrong plug!! It was a 13/16" head that was a bugger to get out as a socket will not even fit for the design of the head. Luckily I had a crows foot wrench and that did the trick!!



The carb boots looked great. The rebuild was easy as pie. Just took everything apart. Sprayed it out, brushed it a bit and blew everything out with compressed air then reassembled. Everything went back together perfectly. I did find two other problems. The rubber mount at the carb was broken and the fuel bowl drain was/is bad. Just the screw, it will not stop fuel flow. SO my thought that the needle and seat was bad wasn't the case at all.
Also I found that the thumb throttle was not properly adjusted and causing the engine to stall at idle.

With everything back together it was time for a test ride. MAN WHAT A DIFFERENCE!!! It started up and idled nicely after just a quick adjust of the idle screw. Its got more power and runs much smoother, but still drips at the fuel bowl.

CW
 

·
Registered
Joined
·
6 Posts
Hey Manaen,, Hope you do not mind me interupting this thread,, but I need some advice. I copied your post to cwlongshot on the carb rebuild and plan to do that soon as I can get to it this week. I have a 1990 Trail boss 250 that has started to give me fits. Last week, we went on an Elk hunt at 8500 ft. elevation and my machine was really blowing the blue smoke really bad. I live at 3600 ft. elevation so there was a pretty good difference in elevation and am not sure that should have effected the carb that much,,,?? I tried opening the air adjustment screw but it did not seem to make a difference and acted like the choke was stuck , would hardly idle with the throttle wide open. It finally stopped. I dissambled carb and did not find any obvious problem, I removed the choke and it started and ran kinda decent but would not rev up all the way. The engine was actually trying to blow the choke brass plug " OUT " of its port,,,!!! I could feel pressure trying to blow the little plug out,,,!!! Is this normal? What could be the problem? I have tried to start since we got back from mountains but has yet to start. Any help? Thank you for your time. Joe r
 

·
Registered
Joined
·
1,104 Posts
Hey Manaen,, Hope you do not mind me interupting this thread,, but I need some advice. I copied your post to cwlongshot on the carb rebuild and plan to do that soon as I can get to it this week. I have a 1990 Trail boss 250 that has started to give me fits. Last week, we went on an Elk hunt at 8500 ft. elevation and my machine was really blowing the blue smoke really bad. I live at 3600 ft. elevation so there was a pretty good difference in elevation and am not sure that should have effected the carb that much,,,?? I tried opening the air adjustment screw but it did not seem to make a difference and acted like the choke was stuck , would hardly idle with the throttle wide open. It finally stopped. I dissambled carb and did not find any obvious problem, I removed the choke and it started and ran kinda decent but would not rev up all the way. The engine was actually trying to blow the choke brass plug " OUT " of its port,,,!!! I could feel pressure trying to blow the little plug out,,,!!! Is this normal? What could be the problem? I have tried to start since we got back from mountains but has yet to start. Any help? Thank you for your time. Joe r

air adjustment screw? are you sure that wasnt the idle jet? if you can tell me what you have for a carb i can help out - i have no clue what you are working on.
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #14
Hey Manaen,, Hope you do not mind me interrupting this thread,, but I need some advice. I copied your post to cwlongshot on the carb rebuild and plan to do that soon as I can get to it this week. I have a 1990 Trail boss 250 that has started to give me fits. Last week, we went on an Elk hunt at 8500 ft. elevation and my machine was really blowing the blue smoke really bad. I live at 3600 ft. elevation so there was a pretty good difference in elevation and am not sure that should have effected the carb that much,,,?? I tried opening the air adjustment screw but it did not seem to make a difference and acted like the choke was stuck , would hardly idle with the throttle wide open. It finally stopped. I dissembled carb and did not find any obvious problem, I removed the choke and it started and ran kinda decent but would not rev up all the way. The engine was actually trying to blow the choke brass plug " OUT " of its port,,,!!! I could feel pressure trying to blow the little plug out,,,!!! Is this normal? What could be the problem? I have tried to start since we got back from mountains but has yet to start. Any help? Thank you for your time. Joe r
Sorry Joe, I cannot offer any advice. I live on the east coast and don't or haven't had any real elevations to adjust for. I do know it makes quite a difference.
Hopefully Cookies will have the answers you need!

CW
 

·
Registered
Joined
·
324 Posts
Sorry guys I was on a two week excursion in the swamps of North Carolina. Beating my trial boss and chasing some whitetails.

Is this normal? What could be the problem?
umm nope its not normal. When you go higher in elavation your engine will run too rich due to the low oxygen content in the air. Turning the idle mixture screw will not fix the problem you need to adjust both the needle and the main jet. Down 1 or 2 sizes on the jet and move the C clip up one notch on the needle. Sounds like your engine was running very rich. That is not an air adjustment screw it is an idle mixture screw. by turning it out you made the mixture even richer which caused the engine to run worse. You probably ended up fouling the plug with will eventually cause the engine to stop running(as you found out). If you routinely go between those two elevations you can jet the motor so it is a compromise between the two. I suspect your engine is currently jetted richer then it needs to be. Which is what caused to extreme richness when you went higher. You should probably also check to make sure your float is setup properly. Also pull your plug and check and see if it is burnt black and sooty. This is an indication that you are running way too rich.

Get your carb cleaned and your mixture correct and then we will see about the other problems with the choke. Oh when you remove and reinstall your carb make sure all the cables are adjusted properly. It is possible that your choke cable is out of adjustment which caused it to run even richer. Also your brass choke valve should slide freely through the entire bore on the carb body. Make sure there is no oxidation or glaze that will cause the choke to stick.
 

·
Registered
Joined
·
1 Posts
Thanks guys.

I checked manufacturers supply, nothing listed for the 2000/2001 TB... Babbits shows nothing either.

I sent a Email to both so hopefully someone will have something for me.

CW
I found a carb kit through ebay motors. I bought one thru a company in northern Idaho but i saw several in different parts of the US.
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #17
Thanks guys.

I checked manufacturers supply, nothing listed for the 2000/2001 TB... Babbits shows nothing either.

I sent a Email to both so hopefully someone will have something for me.

CW
I found a carb kit through eBay motors. I bought one thru a company in northern Idaho but i saw several in different parts of the US.
WELCOME JM!!

I looked on EBay when I did this and it want not offered. (Things change daily) But good news you found one there. I use it allot and usually always look there first...

As a matter of fact, I still needed some bowl drain line. (Fuel line) and found it on EBay and ordered it this AM...:biglaugh:

CW
 
1 - 17 of 17 Posts
Top