I have 2 - 2004 Polaris Trial Boss 330 and have had carb issues since several weeks after the warranty expired. My problem (according to the dealer) is that the carbs are getting gummed up from the gas breaking down. I used stabelizer, and use the quads once a month in the winter and 3 out of 4 weekends in the summer. The most they have sat is 4-6 weeks. The quads wont idle worth a darn, and require the choke to be on partially to get them going.

My questions are this:

1. Is there a manual available to remove and replace the carb as well as clean it?

2. Does this happen to others?

3. Is there anything else I can do to stop this from happening?


Thanks for your time.

-Nutin

 

I have the same problem with my 2004 330 magnum. I have to use a lot of choke to get it started and have to keep adjusting until it will run on its on. Also out on the trail after stopping for a little bit it doesnt start up well. It doesnt start up the first time it usually takes a few times. Once started it runs good.

 

You need to change the needle clip position. Does it run good otherwise? Just runs bad at idle? If you need to choke it to get it to idle then you need to richen the needle. You have to lower the clip to richen it up.

 

Thanks for the advice, will be tearing it apart in the morning..


THANKS!!

 

Had the same problem on ours! My dealer lowered the clip on the needle 1 position, and adjusted the idle mixture richer. He did it
all under warranty, and it has ran great ever since!!!! Starts better, and idles great!

 

Can someone explain to me about needle position. Mine is out of warranty. Is it something I could or would want to try myself. Starting is the problem with mine. It just doesnt start up well. Once warmed up it runs good as long as it is running. Once you shut off the engine it doesnt like starting up. The ETC has been adjusted off and on at the shop. Still the same problem. Its a 2004 polaris magnum 330 with 700 miles on it so far. Like the smooth ride. Just wish I could get the starting problem resolved.

 

Needle position isnt going to effect idle. The mixture screw is what controls the mixture with the throtle closed. Try going richer on the mixture screw. The needle just controls the mid range of the throttle. This should improve the starting, and cold drivability.
When you park the quad, turn the gas to off, and if its gonna sit for a few days or longer, drain the float bowl. This will prevent the crud buildup in the jets, (if the carb is left dry). Its the constant evaporation and refilling in the float bowl that leaves a buildup.
Is the idle speed high enough?
Clymer sells service books, which work out well, and heres some links to online carb sites which might help give you an idea, of how the carb is adjusted and how its cleaned.
jetting
carbclean
another carb clean

 

Hondabuster,
The needle does affect the idle and midrange. After 1/2 throttle the main jet takes over. If the needle is set too low it will run rich at idle, if it is set to high it will run lean at idle. Thats why when the weather gets cold you should richen (lower the clip) the needle to help with cold starts. When it gets hot you raise the clip for warm starts. It is like this on all carbs.

 

Well, then that must mean this and other websites, textbooks, technical manuals and service books, are wrong. Actually I must be wrong then as well, because this is how ive been fixing carbs for years. But im open to explainations, ive been wrong before.
http://www.motocross.com/motoprof/mo...1/carb101.html
specificly the fig 7 where it shows which circuits supply fuel at which throttle openings. And states

Carburetor troubleshooting is simple once the basic principles are known. The first step is to find where the engine is running poorly, fig 7. It must be remembered that carburetor jetting is determined by the throttle position, not engine speed. If the engine is having troubles at low rpm (idle to 1/4 throttle), the pilot system or slide valve is the likely problem. If the engine has problems between 1/4 and 3/4 throttle, the jet needle and needle jet (most likely the jet needle) is likely the problem. If the engine is running poorly at 3/4 to full throttle, the main jet is the likely problem.


My understanding, is if the needle jet, and the jet needle, isnt worn out, the needle doesnt come into play until after 1/4 throttle, and goes until 3/4 throttle...where the main takes over. If you have documentation which shows other wise, id be interested in seeing it.

 

What are you suppose to do when you change elevation?

I go from desert one weekend to moutains the next. Elevation change from 1000 to 6000 ft.

Thanks again for all the information.


-Nutin