Professional jetting for my 2003 KX250 in Orlando?

[svttodd]

Well... I was going to try to jet my 'like new' 2003 KX250 myself to solve the infamous 'spooge' problem. I searched and read many of the forum topics here and I came away even more confused. Each thing that I read seemed to suggest something different for the bike (my bike is basically stock, very low hours, Pro Circuit pipe w/stock muffler, 32:1 93 octane). I want the bike to be jetted for aggressive trail riding here in Orlando (we are near sea level). I want the bike to idle, and not to spooge or foul plugs. Does anyone know of a reputable shop or race tuner that could properly jet my bike. I don't want to take it just anywhere and have some knucklehead try to jet it. I want a 'pro' who knows these bikes. If I can't find a 'pro', then can someone let me know the best starting point so I can let a 'semi-pro' tuner from a local shop get a start towards proper jetting. Thanks. -Todd

 

[James Dean]

svttodd,

Send me an email and I'll help you get it dialed in for your conditions. It shouldn't be difficult with the right parts.

James
JDJetting@comcast.net

 

[Lissa]

If your trailriding your MXer first thing you should do is change the spark plug your using. Instead of the Iridium plug that the bike calls for stock go to a bigger electrode plug like the BR8EG. Bigger electrode, less prone to fouling. I would change your premix ratio as well. It should be 40 to 1. Make sure as well that your not over oiling your air filter. When it comes to jetting on my bike I like to jet it just a hair rich. Not till the point that its dripping spooge out of the silencer or doesn't run cleanly, just rich enough so tempature changes doesn't affect the bike as much. The only problem I had with the stock jetting was that the main jet was to fat. It jetted very cleanly up till I got it on the main. Then it would splatter paint (spittle) the rear fender black. One size smaller was the trick for my application. To get the bike to idle just turn the idle up a hair. It's no (stock) KDX so don't expect it to sit there contently idling away without loading up. Also don't let the bike run on the choke when you intially fire it up. Start it up and turn the choke off right away.

 

[svttodd]

Thanks for the help Lissa and James Dean. I just came back from a local shop where they gave me yet another opinion. They told me to just mix the ratio to 40:1 and leave everything else alone ("do not change jetting"). I like the idea of using a different plug Lissa, but I thought that I was supposed to go with the 'thin wire' type plug to help prevent fouling? Should I go 'hotter' or 'colder' on the plug as well? All I want is a bike that does not spooge too much, and I don't want to have to worry about fouling plugs all the time (knock on wood it hasn't fouled one yet, but with all the spooge, it seems inevitable). I will try a few of your ideas. James, I will be e-mailing you. Thanks. -Todd

 

[Lissa]

I wouldn't mess with the heat range, just a larger electrode plug IMO is much less prone to fouling off-road. I know the reason the manufactures equip their bikes with these exspensive Iridium plugs with the tiny electrode, but I discovered that the small electrode is more prone to fouling out as well as watering out. Also since riding off-road puts different demands on the bike then MX does there is no need for the Iridium plug. I've ridden and raced in Florida before (big scrub and the Alligator Enduro) and do not need to change my settings from what I run up here. My set-up is different then yours, I'm sure (V-Force, stock head pipe w/ FMF Q-Silencer, stock motor w/ lighting coil {flywheel effect}). Your jetting is most likely not far off from were it needs to be; just change the pre-mix ratio, try a UNI air filter element as opposed to the thicker stock unit and a BR8EG. You then should find that the jetting it has now should work a little better. Also if it spooges that much, try repacking the silencer; it's probaly full of black crud.

 

[Steve47]

Man, I live inOrlando and I owned a 03 KX250, now an 04 and hopefully soon an 05!

Jetting a bike is not rocket science and you don't need a pro rider to do this. In fact, a lot of pros aren't very good mechanics.

Mine was running very crisp. The bike comes very close from the factory. 40:1 is a good start to get rid of the spooge(but it's OK to have a little if the bike idle long) Air screw should be enough to fix your issue and worst case, a leaner pilot.

I'm at Bithlo and Pax all the time, stop by and say Hi, I'll help you out. #47 on a Seminole Powersport KX250 / No fear gear.

 

[svttodd]

Sorry, I didn't mean a pro rider, I meant a 'pro' mechanic (as opposed to "my buddy's cousin's sister's mother told me that the jetting should be abcxyz"). I got the problem solved. I spoke with the original owner and he helped guide me through the bike setup. He had already installed different jets, and with some fine tuning, I was able to get rid of the spooge without any major modifications. A salesman at the dealer who I bought it from aparently turned the air screw all the way, thinking that it was the idle (!), adjusting the air screw and the idle screw fixed most of the problem. The dealership was nice enough to have the previous owner contact me and he walked me through the tuning. He seemed very meticulous, and aparently he had the bike set up right, but someone at the dealer must have 'adjusted things' out of wack. On top of that, the air filter was way over oiled. More power and a lot less spooge. Time to repack the muffler though. Thanks for the input everyone. -Todd