[Strange 300ex jetting issue, need advise...] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

Pages:1

Strange 300ex jetting issue, need advise...
(Click here to view the original thread with full colors/images)

Posted by: flyboy1294

Hey guys,
I'm a 400ex guy, and a fairly noobish one at that. But my family owns a 300ex that isn't mine, but I'm still responsible for the maintenance of it and I only have time to fool with it around 2-4 times a month, so if you all could help me figure this out, when I get back I'll just try to get it put back together and save some time.

Here is the deal,
stock 300ex (Moose Air-filter, but it's not different than stock.) and the jetting was 'ok' this summer. Maybe a bit in the lean or rich direction, but still well tuned enough to where I thought it was good to ride.

About 2 months ago, it started acts a bit odd. It would bog when you'd punch the gas (used to be flawless), but it wasn't enough to make me concerned.

Then 2 weeks ago, it was bogging significantly, being extremely cold natured, and not performing as it used to. I changed the sparkplug because it seemed to me that might be the issue, also I cleaned the airfilter real good...

This week, however, it has gotten to the point where its not ridable. The bogging is not only when you rev the bike in neutral, but when you try to change gears it will bog and cut off and throw you over the handle bars if you're not careful. I took out the plug, and checked it, its like burnt black, and it's less than a week old. I'm guessing the problem is the jetting. What do you guys think, lean or rich? And what size jets do you recommend?

Thanks for helping out a fellow noob.

Posted by: no1 300ex

If the spark plug is black its to rich. If the plug white its to lean.

Posted by: flyboy1294

Well it was blacker than night. So it's definitely too rich.

Does anyone have any recommendations of how many jet sizes to go down?

Posted by: no1 300ex

What does it have for a exhaust? I would start by pulling the carb and give it a good cleaning, then get it adjusted properly. It might just be full of crap if it is not used much.

Posted by: flyboy1294

Exhaust, along with the rest of the bike, is totally stock. But yeah I will try to clean it really good over the weekend or something

Posted by: flyboy1294

I won't be able to tear the bike down until this weekend coming. But I made a video to show you what its doing, sort of.

Please don't be hatin'. I was tired and it was late, I know the video sucks.

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/bPJHXfQCqrI&hl=en&fs=1&color1=0x5d1719&color2=0xcd311b"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/bPJHXfQCqrI&hl=en&fs=1&color1=0x5d1719&color2=0xcd311b" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

Posted by: no1 300ex

I watched the vid. Mine does the same thing when I first start it and the machine has not been used for a few weeks. If ya hit the gas it dies, however mine will clear up after a few min. of warm up. When I first got the 300 ex it had been sitting unused for a long time. It would start & run but if you hit the gas at all it would die (warm or cold). I pulled the carb and cleaned the chit out of it . I also use sea foam in the gas. So far no problem.

Posted by: flyboy1294

quote:
Originally posted by no1 300ex
I watched the vid. Mine does the same thing when I first start it and the machine has not been used for a few weeks. If ya hit the gas it dies, however mine will clear up after a few min. of warm up. When I first got the 300 ex it had been sitting unused for a long time. It would start & run but if you hit the gas at all it would die (warm or cold). I pulled the carb and cleaned the chit out of it . I also use sea foam in the gas. So far no problem.

Sounds like it needs to be torn down and cleaned. Then ran on higher quality gas. I will check back after I do those suggestions.

Posted by: flyboy1294

I don't even know what to say at this point. WTF?
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/sacoO6yXNHY&hl=en_US&fs=1&color1=0x5d1719&color2=0xcd311b"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/sacoO6yXNHY&hl=en_US&fs=1&color1=0x5d1719&color2=0xcd311b" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>