I have a 2004.5 sportsman 700 with the " up-dated ignition". Started having problems of it not having any full throttle a while ago. Have tried several things to get it to run better,but with no luck. Started getting to be more of a problem ,so i started digging in a little deeper. It will idle o.k., can run through low speed up to about medium throttle,up to 4000 to 5000 rpm o.k. . But if you give it full throttle it will just die!!!, bog down to nothing. Let of and it runs fine. Have had the carb of several times and cleaned and checked all the settings and seems fine. Tried running with muffler off to eliminate any obstruction and no difference. I thought the spark looked weak, pulled the coil and found one plug wire severely pinched from the factory. Went to a dealer to check on a coil and he said ,coils don't go bad! He confirmed the up-dated ignition by the year and put new plug wires on the coil for me. which did not help. After reading some forums here, i noticed some similar symptoms ( gas pushing back into the air box while running with filter off) ( getting gas in the oil) symptoms of poor ignition. Now the carb adapter is cracked for the 2nd time, have one ordered. Really getting to my wits end with this thing, any and all help will be appreciated. Thanks Terry

 

Have you checked for water in the fuel? Have you tried to seal the cracked adapter to see if it helps? Have you installed a carb kit instead of just cleaning the carb? If it's shooting back fuel into the air box could be a worn needle and seat,float level problem.I'd eliminate the carb and adapter first,then move on to possible electrical problem if this doesn't help. Polaris Sportsman 700 carb rebuild kit 03-417
Plus here's a link for a 2005 MV7 pdf service manual that shares the same carb/electronics.http://gh-ftp.com/ORV%20Manuals/Pola...7%20-%20SM.pdf

 

This has been going on for some time, so i don't believe the gas is an issue. I did tape up the adapter to seal it up, ran better at idle but still no full throttle. Have the adapter and carb kit on the way. Will post back after i get them installed. I am puzzled about this: If i'm riding along at half throttle and i go full throttle and it just bogs out completely, and then let off and it runs just fine. If it just flooded out wouldn't it spit and sputter until the raw gas got burnt out? Wouldn't this be more of a lean condition? Thanks for your help. Terry

 

Usually when this happens it's a lean bog especially if you have any jet stoppage, air leaks, contaminated fuel,etc,but running rich can sometimes do the same thing. Bogs then once you let off the throttle,excess gas can clear through the exhaust valves then the engine can resume the load. Another way to check is to just pull the spark plugs and check the color after the engine has run awhile. If electrodes are really light or whitish color,then you're running lean,if they're dark,carboned up, you're running rich.Once you eliminate the fuel and carb as the possible problem or any lean conditions such as the intake manifold leaks and you still have problems,then go on to electrical trouble shooting. Just a process of eliminating one thing at a time.You'll find it.

 

O.K. while waiting for the carb kit and adapter to arrive i pulled the carb and adapter. Cleaned the plugs and gapped and decided to try one of the plugs in my lawn tractor just to see how much spark i get. WOW, i get like a mini explosion for a spark compared to the little straight line of spark i get with the atv! Is this really my problem. Anything i can check while waiting for my parts? Also, what's your thought on the upgrade cdi & external coil kit made by RMSTATOR. It claims to fix the problem without replacing the stator. Terry

 

Can't compare spark from two different vehicles..Plus you now have a dci ignition system instead of the old magneto triggered systems such as the Ducati.It can crank up now with as little as 7 volts from the battery and is a more efficient system. I don't even know if the RM stator kit would work properly.. It's main purpose was to use the old Ducati lighting coil from the stator and changes it to the ignition circuit. Costs about 250 bucks,but the reason I never thought much of them when they came out is that the lighting coil of the Ducati ignition can fail(have had that happen too) then your out of luck!Have to find another stator or just suck it up and do it the right way! For all people that have problems on the older Ducati systems,best to replace it with the entire Kokusan kit that you already have in your machine.Just wait until you have the carb kit and new adapter.

 

Got the carb rebuilt and new adapter and all put back together. Set the low speed screw at 1 1/2 turns open. Started up great.Starts cutting out at mid at mid throttle, same at full throttle. Took for a short ride. The farther i went the worse it got, barely made it back to the house. Pulled a plug and running rich. The shindy 03-417 kit i used had a main jet of 157.5 if i remember correctly, mine was a 155.

 

You can always raise the needle clip(lowers the needle) to see if it helps on mid range. Float level setting is critical on your bst34 carb same as it is on the bst40. Manual shows to set the carb on it's back side(air box side),the top of the float should be 13-14 mm from the carb body while float tab is resting on the float needle plunger.If adjustment doesn't help along with swapping out the main jet back to the stock jet,tuning in the fuel screw a little,then I'd start with electrical resistance checks on the ignition. Kokusan is a good ignition system,but with all things electrical and mechanical,problems can happen.

 

O.K. Back to the factory 155 main jet, needle set in middle slot same as it has always been. Float set at 1/2" as per spec.. Idle mixture set at 1 1/2 turns open. Starts and idles fine. Can ride a short distance at mid throttle ( still bogs out at full throttle), Then it starts to cut out at any speed except idle. Whatever the problem it is progressively getting worse. Before it just bogged out at full throttle, would run fine at any other speed.

 

When it's warm and does this pull the fuel line from the carb and crank the engine over. Should be a good stream of fuel. If it isn't then a weak fuel pump could be the problem or the carb vent or tank vent could be obstructed.If none of this helps and you say it get's progressively worse as it warms up,still could be an electrical problem. Look at the trouble shooting guide in the manual I posted previously.