2 stroke always rich ????

[cr25096er]

2 stroke always rich if not reved much? i jetted my cr250 about a month ago and ther plug was nice tan but that was after wot up a hill. now it is a little dark almost black and a little wet around the edge(no where near the electrode) so my Q is will a 2 stroke be rich is not reved much? the last time rode was through the woods behind my house and i was putting and i think the bike got to be completely warmed up but when i was riding up the drive way i nearly stalled it and just rolled the throttle on and wheelied then let it idle for a few seconds but i fighre it wasnt enough to clear the plug. any thoughts? ive never fouled a plug and im no ripper yet. it seems nice and clean through the entire rev range so i dont think its rich. it also dosnt smoke much.any thoughts?

 

[dell30rb]

You're probably okay. The plugs are usually a little bit on the darker side if the bike hasnt been revved much.

I was really suprised when I took apart my old 1994 evinrude 3.3 hp. Dinghy motor. The plug was a perfect tan. Its the original Plug too.

 

[los36]

cr250-
You can't read jetting from a plug unless you are running wide open and then hit the kill switch. So don't read too much into the wet plug if you're just putting around.
Putting around will cause the engine to load up; extra fuel will gather in the crankcase because the engine is not running fast enough to pump it all through. This will cause your bike to respond sluggishly or stall at idle speeds until you rev it a couple of times to "clean it out". This cannot be fixed with jetting.

 

[cr25096er]

k thats what i was thinking

 

[scotth]

los36,

What can fix this condition if it is not possible with jetting? I have had similar problems costing down mountain trails. The bike loads up by time i reach the bottom and when it is time to go up the next hill, big bog. Now I no, I can just rev the motor every now and then on the way down, but what would you have to do to eliminate the condition?

 

[los36]

I'm not sure. I think that in general, engines that are designed to operate at lower RPM's run better with smaller carbs. I believe they help with low-RPM torque and proabably lessen the fuel going into the engine; reducing the chance of loading up.
I'm making this inference from reading about putting 38mm carbs on 125 for more high RPM horsepower while giving up low RPM power and response.
Perhaps some fine tuning of your air screw each time you ride might help, but I'm sure it won't eliminate all of the loading up.

 

[scotth]

That sounds correct, I used to have a KDX220, which had a 33mm carburetor. It would run all day at low RPMs and never really load up. I remember reading, that the smaller carburetor gave it better low-end power. The theory was that the smaller opening increased the velocity of air entering the carburetor at low rpms. On the top end, the KDX would signoff vary quickly. Now I ride a KX250 and am still learning how different the two bikes are. Am I expecting too much, thinking that the KX should have the same low end behavior as my KDX had. :think:

 

[los36]

You're right. The smaller carbs increase the velocity at lower RPM's. That probably keeps the fuel atomized better in the fuel/air mixture.
You probably cannot expect the KX engine to behave as well as the KDX on the trail. On the track, the only time you shut down is for a couple of seconds in the air and going into turns.