theclinkster

Member
Feb 17, 2006
8
0
I have a 2000 YZ125, and am running BR8ES in it. There is a good bit of smoke on cranking, and starting off, and it sounds alittle bogged down. Once it gets going it is awesome, it has a problem going slow. The bike fouls plugs at least 1 in riding it each time on the track. The plug when we remove it has a good bit of oil on it, and it is obviously dark, and burnt. We have adjusted the airscrew, and have it set at 1 1/2 turns out. The idle sounds good, so I think we have it set good on there. Any ideas on what to try next. I got this bike back in December, and it came from Tennessee, and we are in Charlotte, NC. Do you think that may be enough altitude change, and temperature to be causing this jetting problem.
 

nikki

Moto Junkie
Apr 21, 2000
5,802
1
If the plug is brown and fouled, this sounds like the bike is too rich. If it was hot, the plug would be white (lean). You want the plug to be a nice tan color.

I would try one step leaner on the pilot jet.

To get to the pilot:

-loosen the carb clamps (one that goes to the airbox, and one that goes to the clyinder)
-twist the carb so you can see the big nut underneath (I think it's a 14 mm, maybe 17 mm?)
-remove the nut, beware, the gas in the float bowl will drain out
-you'll see both the main jet and the pilot jet in there - if I remember right, main is in the middle (hex head?), and pilot is off to the side (small flathead screwdriver to remove it)

Check what size pilot, and maybe try one-two steps smaller. Adjust your air screw again with each pilot change.

Good luck! :cool:
 

nikki

Moto Junkie
Apr 21, 2000
5,802
1
Another thing - what kind of premix and what ratio are you using? The whole smoke/oil thing indicates maybe it's something other than jetting.
 

CamDayKX125(4)

Uhhh...
Jan 20, 2006
182
0
my bike runs a BR9ES OR EG whichever we can find. were pretty sure the top end is my problem because i foul anywhere from 2-4 plugs on my kx 125 every time i go to TNT.
 

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