just bought a 98 300ex NEED HELP!

[mackspeed]

hey guys, i just got a real good deal on a 98 300ex, this is my first atv. i bought it from a guy who hasn't ridden it in 3 years but said he started it up everynow and again and that there are no problems with the engine. it seems to be in pretty good shape, but i've had some trouble getting it running. it seems like a carb issue and i dont really know much about how to tune these things. everything on it is stock.

i can get the engine to run if i turn the choke on and blip the throttle giving it a little gas, it doesnt really like to idle on its own. sometimes it will idle for a little bit but at a very low engine speed and then it stalls.

if i turn the choke off it wont even start.

i've changed the gas, checked the plug and the air filter is fine.

what are the next steps for me to try to get this engine to run?

thanks alot in advance.

[beak7707]

If it has been sitting that long I would go ahead and clean the filter and put a new plug in it. I would say the carb needs cleaned! I would take it off and clean all the jets and bowl. I have a repair book if you want I can look at where the air screw needs set and all that good stuff. But if its all stock I would say nothing has been changed. I would just try cleaning the carb and new plug first.

[mackspeed]

yeah, that would help if you dont mind. i know i should pick up a manual.. ill order one tomorrow, but it wont be here till the end of the week, i'd like to luck into getting this running before then so any ideas or settings anyone has would be nice.


where exactly is the air adjuster on this carb?

[mackspeed]

also, dont know if this helps diagnose the problem... but when the engine is running (by means of me choking it and lightly squeezing the throttle) the motor occaisionally backfires, i can here some popping both in the exhaust and carb inlet. does this mean its running too rich?

[TheFontMaster]

Carb clean sounds like the best thing to do. Also have you tryed riding it at all. I bet it would idle fine once it gets wamed up, mine does kinda the same thing, except not as bad, and it runs perfect once i run it around for about 5 muinutes. And as for the backfireing, check to see if there are any leaks in the exaust. But I'm not shure what jetting changes would fix it if the backfires are a jettin related problem.

[mackspeed]

how do i increase the idle speed?

[buddy what not]

to increase the idle speed theres a screw right above the electric starter its a black plastic one it kinda back in a bit but right above the starter

[mackspeed]

which direction do i turn it to increase the idle speed?

what about the 2 adjustment screws on the carb, can someone explain those to me?

one seems to drain fuel out of the bottom when i loosen it and there is another one on the bottom.

thanks again.

[beak7707]

Yes the big nut on the bottom of the carb will drain the bowl. The other screw on the bottom the small one, is the air/fuel adjust. If it is backfiring it is lean, but I really think you just need to clean the carb. I would say the reason it is lean, is because the jets are plugged up with gunk. Tear the carb apart and clean the bowl and the jets.

[250rider]

i have a shop manual for sale but its for a 250x, pretty much everything is the same unless u have a problem with ur starter. other wise it will be exactly the same thing for ur 300ex. pm me for a price if u would like.