Carb issues, help?
Dec 13, 2012 | 06:09 PM
#11
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Joined: Jun 2008
Posts: 24,350
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From: North Texas
Guys, I have the same problem as Wayne on my 2003 Trail Boss 330. I bought it used after it sat up for two years. It has the same CV carb. I pull the carb off, soaked and cleaned it. I'm certain it is assembled correctly. It started right up afterward and idled great. But at 1/4 throttle it began to run rough and at 1/2 throttle or more it seemed like it was starved for gas and died out. I pulled it again, cleaned it again with the same results. I've clean that carburetor once a day for four days. Nothing changes. I'm pretty sure its not dirt or gum anymore. My main jet was stripped so I couldn't get it out but I cleaned it well. I can fill the tube the jet screws into with gas and it runs out through the carb with no problems. I cleaned - not replaced - the needle jet and the jet needle. The pilot jet is at 2 turns. ( thanks to this forum!) I went through the fuel pump today. Just cleaning it and the lines - I didn't have a kit. same results. I've run it with the airbox on, off, with the two vent lines hooked to the airbox and without them hooked up. no changes... The needle jet looks good. The jet needle looks ok. The spring and diaphragm assembly works. I should mention that 2 days ago after cleaning it, it ran great! I rode it for about a 1/4 mile through all speed ranges and it ran really good. I pulled it in the shop, started put things back together and thought I'd like to hear it run one more time before I quit for the day. It started right up, idled great but for some reason, would not run past 1/4 throttle just as before. What am I missing? Just to be certain, those two vent tubes in the top rear of the carb are supposed to go to the airbox..... aren't they? Thanks
Dec 14, 2012 | 08:01 AM
#13
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Joined: Jun 2008
Posts: 24,350
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From: North Texas
YES! All carb lines vent to the atmosphere,they do not go to the air box, T off into the carb overflow line,etc. Hope this solves your problem . The air box has two inlet nipples,but only uses one hose on the 330. The other nipple should have a rubber plug over it. This same box was used on Sportsman 500 models where both inlets were used. The crank case vent and oil tank vent went to the air box. OPT
Dec 15, 2012 | 05:25 AM
#14
Weekend Warrior
Joined: Dec 2012
Posts: 4
Likes: 0
Update, routed vent tubes as instructed. Still can get only 1/4 to 3/8 throttle before it stalls out. Up to that point it runs great. By working throttle quickly I can get the RPM's higher but not so with a steady throttle. I put clear fuel lines on all fuel points so I could watch the gas flow. It appears to have plenty of fuel volume but no great amount of pressure. I don't have a vacuum gage to test the fuel pump, though the bike will not start without the pulse line hooked up. It possibly ran some better with new fuel lines or tvat could have been wishful thinking!! But I did notice a lot of air ( bubbles ) in the fuel lines. I hate being a parts changer but I'm lost so I'm replacing the fuel selector- it doesn't completely close off when it's in the off position anyway. I found a used coil not far away that's reasonable... Maybe the coil is breaking down under a load??? The same guy has a used carb but we haven't decided on a price yet and I've ordered a fuel pump kit. And I'm changing the plug. Do you guys have a preferred plug? AND if none of that helps, all ya'll need to come to North Alabama, you know, we are the space rocket Capitol of the world..... Because you don't want to miss seeing the first ATV tied to the back of a rocket and blasted off to outer space !!!!!!
Dec 15, 2012 | 08:20 AM
#15
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Joined: Jun 2008
Posts: 24,350
Likes: 44
From: North Texas
Fuel selectors(fuel valves) did have a habit of getting stopped up.I replace a few of these over the years. Some would run good on reserve, run crappy on the main position or vice versa after a few years. Even tank filters can get stopped up on the main and reserve lines. Fuel pumps can get trash build up,etc. A lot of the problems on these are because of ethanol fuel.It can ruin rubber o rings,eat fuel lines from the inside out,affect plastic diaphrams in the fuel pumps,etc. OPT
Sep 2, 2013 | 03:10 PM
#16
Trailblazer
Joined: Sep 2013
Posts: 31
Likes: 0
hi
yes I have..I just came in from adjusting the rick lean screw under the carb..it was set at 2 1/4 turns..i turned it in and backed out to 1 turn and the needle adjustment for the throttle i brought all the way up to the first slot...helped about 50 % but still a little boggy when first give it throttle
Sep 3, 2013 | 08:41 PM
#17
Weekend Warrior
Joined: Dec 2012
Posts: 4
Likes: 0
Grasping at Straws
I got my 330 Boss running pretty well. It is cold natured but once warmed up, does great. To finally fix my bog problems, I watched the slide and it seemed to be coming up way too early. I adjusted the stop positions as much as possible and still no help. I ended up putting a couple of small washers on top of the needle to retard the slide/needle movement. I don't know why I had to do that but it worked ok.
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