think i have a fouled plug

[gstaten24]

so my i have been working on my friends cr125 getting it jetted to run at the current elevation. he went up 4500 ft in elevation and i changed the main jet from the 360 he had in it to a 340. all he has done to it are fmf pipes. what its doing is when you get on it, it feels like it boggs down and it has no powrband. i think its a fouled plug cuz the tip of the plug was completely black not the tan mocha color that is desired. am i correct or do you guys have any other ideas? also it leaked coolant out of the overflow tube but not much and we made sure we let it cool and put some more coolant in it. when i checked the plug i held it WOT for a couple seconds then checked the plug and it was smoking out of the top of the cylinder when i took the plug out. that is normal right?

 

[IndyMX]

Sounds like it's still too rich to me.. If the plug is fouled, more than likely it just won't run.

If you fill the radiator to the neck, it will push some out.. Water expands when it's hot, so it will need a little head space.

The smoke out of the cylinder depends on what it looks and smells like. If it smells sweet like coolant, you have a blown head gasket..

Check that before doing anything else. Once you know the engine is mechanically sound, then you can attempt to jet it. Otherwise you are wasting your time.

Also, start your tuning your jetting on the pilot, then the needle and then the main.

 

[gstaten24]

Ok I will try that, n it didn't smell like coolant so I'm pretty sure it's good to go there. Does the pilot make a big difference cuz I was always told that's more for like idling

 

[IndyMX]

They all matter..

Read this.. It should clear up your jetting questions.

http://www.dirtrider.net/justkdx/carbtuning.html