Hi. I hope someone can put me on the right trak. Any help is much apprciated.

I have a 2003 Sportrax 300 ex, completely stock.

I hadn't started it in about a year, until recently. It starts ok and idles, but if I give it any gas, it dies. Under throttle, the bike gives a whaop whaop whaop sound and dies immediatly. I thought maybe the throttle jet was plugged, from old gas.
So I removed the carb and cleaned it out with carb cleaner. Put it all back together. Replaced the gas with new 92 octane.
It's still doing the same thing. Any idea to get me looking in the right direction?

Thanks!

 

To clean the carb, it had to be totally disassembled, all jets removed.
You dont mention if you removed all the internal parts of the carb, so I dont know what you have done. More info please.

 

Thanks for replying.
I've removed the carb, removed the two jets. Sprayed them out, cleaned the bowl and float mechanism. Reassembled, and replaced the gas.

 

try taking off the carb put gas in the cylinder and putting the carb back on and hooking the gas back up and if it works for a minute or at least goes it means ur carb is too small and cant give enough gas

 

If it's set up as long as a year the frist thing i would do is check to see if it's firing , get a new spark plug and remove the old one then put the spark plug boot on the new plug before putting the new plug in the motor ; Then try holding the plug by the rubber boot and touch the bottom of the plug ( metal threaded end ) to a unpainted metal part of the engine ; the head would be the best spot like one of the fin's of the head ! Touch the plug to the metal while holding the plud with the rubber boot ( so you won't get a shock , and try turnning the motor over while looking at the plug ; you should not only see the spark but also hear a popping noise ! If you see a blue spark jumping from the gap of the plug and or hear the popping noise then it's firing ! If it's firing put the plug in the engine ( but make sure the plug gap is set right before you put the new plug back in the engine ) and tighten up the plug put the rubber boot back on the plug ; then you're ready to go to step 2 ! In step 2 you are going to see if it's getting gas to the cyclinder , put it on full choke ( that is if it has a manual choke ) and try to start it if it's getting fuel to the cyclinder it should try to start , or at least pop or backfire through the carb or exhaust pipe ; after you've done this let us know what happen's ! And i forgot to ask you if your quad has a 2 or 4 stroke ? I'll deffently need to know this before i could even start to give out anymore help or info , I have a Haynes Owners Workshop Manual : That cover's the TRX300EX and TRX400EX ATVs itye also cover's 1993 thru 1999 year Model's , and the Engine Size's are 282cc and 397cc Engine's , i hope i didn't just waste your time reading this reply ; but maybe they haven't changed that much from 1999 to 2003 ! williebee

 

Willie, he has spark, it runs at idle. Also if you have the manual you should know that its a four stroke. He indicates that during throttle it doesnt rev properly.
If the bike was running good when parked then the things that could have changed are sticking valve, gummed carb, clogged air cleaner, clogged exhaust.
To begin, have a look up the exhaust, do you see any mud dobber nests, those will cause that very problem, run a long screw driver or some type of rod up the exhaust to make sure its clear, next try running without the airbox lid on. The air filter must be in place, and clean and oiled, it wont run well without the air filter.
If it still wont run after doing these things, then you will need to have another look at the carb there may still be some fouling that you have missed in the passages.

 

Thanks for the replies.
Yes, I do have spark, and it runs pretty smoothly at idle. I've tried running without the air box, but no difference. I'll check for an exhaust blockage when I get home.

What's strange is that as soon as I hit the thottle, its like the gas was shut off. There is no RPM increase at all. It just dies. If I let go of the throttle before completely dying, then ususally the idle will kick back in and it will return to idle.

It seems that there is maybe two valves for gas; a throttle valve and an idle valve? When you hit the throttle, the idle valve closes and the throttle valve opens, only my throttle valve is blocked, so it gets no gas. I don't know if that makes any sense? Do these bikes have two valves like that? When I had the carb open, it looked like there were two needle valves. I removed both and sprayed cleaner through them, but it didn't make any difference.

 

Have you checked to see if the accerator pump is working?
Is the intake all stock?...lid on?

 

i have a 300ex fourtrax its the same as the sporttrax just different name on the seat the carb has a butter fly vaule, slide that connects to the needle and a squrting system when you give it full throttle it shots gas in to the moter. to check if your carb is working open the throttle see if the slide and vaule open. to check the squirting system but gas in the bowl and open the throttle quickly and see if it works. if the vaule opens and the slide dosent you can do one of 2 things 1 get a new carb or 2 rebuild it. if the squirting system dont work its not a big deal.

 

Yes, all stock.
I don't know about an accelerator pump. Where can I find it?