hello iam a new member

[dirtrider831]

ok so i have an 03 trx400ex last time bike was ridden was last year so its been sitting for a while , but the bike was running fine but had an issue with the batteries , it would kill my batteries so i found out my rectifier was bad so i replace it and did tune up changed oil spark plug cleaned air filter , so finally started bike up it starts fine with choke on and idles but once u take choke off it dies ?? can some one help me here please any suggestions ? thanks

[Here 2 help]

Carb is probably gummed up with gas varnish. This happens very quickly with current low octane alcohol blended fuels (as little as 30 days) and a little longer with high octane fuels (about 90 days). The length of time it takes to gum-up depends on the actual grade of gas used (87 with alcohol gets an appx. 92 rating), the actual percent of alcohol the fuel has, whether the petcock was left turned on or shut off, and your locale.

Alcohol absorbs moisture (i.e. HEAT fuel deicer is mostly alcohol) and it will absorb moisture out of the atmosphere. If you live in a rain forrest it absorbs moisture faster than if you live in a desert. The moisture causes the alcohol to separate from the gas and the water/alcohol mix is highly corrosive to steel and aluminum. The alcohol causes plastic to swell and deteriorate.

Since your "couch" runs with the choke on; is is most likely that only the pilot jet is clogged. Take the carb off and if you don't want to invest in the Professional grade of carb cleaner (Berryman Chem-Dip 0901 @ appx. $40 per gallon), take it to a shop and have them clean it for you. Spray cleaners are about as good as trying to take paint off with water.

Once the carb is clean and the fuel tank flushed (use denatured alcohol or lacquer thinner to clean the inside of the tank), put in some fresh high octane (92 but no higher than 95 octane) gas without methanol (if possible) and go have a ball.

[dirtrider831]

thanks for the help but let me tell you i took this carb out twice unscrew the jets out spray carb cleaner right thru them so they dont seem to be clogged cleaned the whole carb put new gas (89 octane) i dont think that seemed to be the problem ?? i mean its logic the problem that i have it just has to be in the carb but everything seems to be nice and clean

[Here 2 help]

If you are convinced the carb is not the problem, check the valve adjustment.

[dirtrider831]

i spent hours and hours on this bike today trying to figure out whats wrong and still same problem I cleaned out the carb again and i did check the valve adjustment and they werent too bad i mean we talking bout .001 off so i set exhaust to .005 and intakes to .004 one other thing too the air fuel mixture screw (the one on the outside of carb in the bottom towards the head) what should that be set at ? i have it like about 2 1/2 turns out . what other issues could i be having ?? ive taken my 02 crf450 carb apart in pieces and that bike runs cherry idk whats wrong with this trx400 ???? any suggestions will help thanks

[Here 2 help]

OK - the position of the fuel screw is unimportant at this time. I am fairly certain you are not getting fuel through the idle circuit. That's why when you choke it, it will idle. The choke reduces the amount of air allowed through the carb forcing it to run richer. The choke butterfly is spring loaded so it opens as necessary to prevent the engine from over-choking. i.e. it opens as the engine revs. The fuel screw is adjusted with the engine at full operating temperature for a smooth idle, but it has to idle first.

If you have time and would trust me to look at (fully service) that carb (I'm in Illinois), I will do it for the cost of parts, if any (most carbs can be rebuilt without any new parts) and postage. Occasionally a carb is damaged beyond repair, but it is fairly rare. Water and alcohol sometimes corrode the passages within the carb either blocking them completely or perforating a passage rendering it useless to the control of air or fuel.

Since I haven't seen it and you say it was operating last year, I'm betting it can be repaired. email me at latebird@hotmail.com Steve

[dirtrider831]

hello i wanted to come back and tell you what i found out with this quad , 1st of i want to thank you for helping me out . so for all you people out there that might of been wondering if i ever fixed this problem yes i did and what i found was my pilot jet was plugged i mean i took it off and sprayed carb cleaner before but didnt bother sticking a very small object to clean inside the jet itself , so finally did that and put everything back together fired the bike up took choke off finally idles and runs good .

[Here 2 help]

Glad you got it fixed, but as I said early on - spray cleaner is ok for cleaning the surface. As for cleaning the internal parts, spray cleaner works about as well as pouring water on grease. My bet is if you disassembled the carb and soaked it in a commercial cleaner, it would have worked the first time.

The lesson to be learned here is: if a carb sets for a long period of time (over 30 days with cheap gas) the pilot jet (the one it idles on) can clog and cause the engine not to idle. The clog does not have to be 100% - a 50% clog will keep it from idling and spray cleaner will spray right thru it, but the clog is still there.

Since you got the jet cleaned by poking something through it, it probably still has some varnish in it, but running with good gas will finish cleaning it over a period of time. Next time you park it, drain the carb - then try starting it to suck all the passages dry - and leave the drain open in case the petcock would start leaking.