300ex:cold natured or a problem?

[s.ga.rider]

I have only rode my 03 300ex twice(I just got it) but I noticed its kind of hard to start. When it starts if you even think of touching the throttle it cuts off and even after 4 or 5 minutes of idling you still have to fidget with it to get it to rev. After that it runs fine. Its stock with the exception of a k&n filter(dont know if that will have anyhting to do with it). After riding it it starts fine as long as it doesnt sit an extended time. Is thee something I can do to fix it or is it even a problem. It may just be cold natured as hell. I changed the oil, filter and plug by the way and checked the air filter. Could that be making it run rich or lean and be causing the problem? I live in south ga. so its not that cold(in the 80s today).

[Trevor]

They don't like being cold. Give her some choke and let it idle for a couple of minutes.

[300exOH]

300ex's are cold natured. There isn't too much you can do. You could try turning the pilot screw out 1/4-1/2 turn or even go up one size on the pilot jet but it will still need time to warm up(5-10 min.) Since you added the filter it may be a touch leaner than stock at idle. They are very lean from the factory to begin with.

[sled_ed 300ex]

like they said its the jetting so you just have to play with it and adjust it to the tempurature and stuff.

[bwamos]

Originally posted by s.ga.rider
I have only rode my 03 300ex twice(I just got it) but I noticed its kind of hard to start. When it starts if you even think of touching the throttle it cuts off and even after 4 or 5 minutes of idling you still have to fidget with it to get it to rev. After that it runs fine.

That's perfectly normal for the 300ex. Air cooled, lots of metal, takes longer to heat all of that up.


Its stock with the exception of a k&n filter(dont know if that will have anyhting to do with it).

You probably have a 122 main jet in it. Which is a little lean anyway. Swap it out for a 125. It should help out your throttle response on the top end a little. The header is the main restriction.. so you dont need to go up much. The 125 should be perfect. If it has a 125 in it now (it may, because of your lower altitude), put in a 128.

After that, turn IN your airscrew (makes it richer) a 1/4 turn. If it starts popping on deceleration.. turn it back out an 1/8th.

[300exOH]

Originally posted by bwamos


After that, turn IN your airscrew (makes it richer) a 1/4 turn. If it starts popping on deceleration.. turn it back out an 1/8th.

I thought out was richer and in was leaner:confused:

[s.ga.rider]

The way it was idling rough I thought about bad gas. The guy I bought it from said it had been sitting for about a month. I took off the tank, drained the fuel and refilled it with fresh gas. I fired it off with the choke on and it ran great. I guess the gas was bad. It crunk up on the first try and idled great, reved great.

[bwamos]

Originally posted by 300exOH
I thought out was richer and in was leaner:confused:

No, the 300/400 carbs have an air screw not a fuel screw.

Some carbs have fuel screws, some have air screws.. the 300ex/400ex/250x have air screws.

Turning it out (counterclockwise) pulls the needle away from the hole allowing more air through. Turning it in (clockwise), pushes the needle into the hole reducing air flow.

This is why you start out at 1 turn out (rich), and turn the screw out until the engine stops increasing rpms (going leaner until it hits optimal fuel/air ratio), then turn it back in a 1/4 turn to put it in the rich side for saftey.


The way it was idling rough I thought about bad gas. The guy I bought it from said it had been sitting for about a month. I took off the tank, drained the fuel and refilled it with fresh gas. I fired it off with the choke on and it ran great. I guess the gas was bad. It crunk up on the first try and idled great, reved great.

Great! :) I was assuming you already changed out the gas.

If you notice it running hot.. you may still want to swap out the main jet with one size larger.

[300exOH]

Originally posted by bwamos
No, the 300/400 carbs have an air screw not a fuel screw.

Some carbs have fuel screws, some have air screws.. the 300ex/400ex/250x have air screws.

Turning it out (counterclockwise) pulls the needle away from the hole allowing more air through. Turning it in (clockwise), pushes the needle into the hole reducing air flow.

This is why you start out at 1 turn out (rich), and turn the screw out until the engine stops increasing rpms (going leaner until it hits optimal fuel/air ratio), then turn it back in a 1/4 turn to put it in the rich side for saftey.



Great! :) I was assuming you already changed out the gas.

If you notice it running hot.. you may still want to swap out the main jet with one size larger.

Makes sense. I have to look it up in the manual so I get it right if I mess with it so I never commited it to memory. Know I know. Good info.