Rich but runs good

[uts]

I have an 86 CR250. It runs really well but fouls plugs after about 3 hours, quicker if I am putting around. The plug is always black and oily. I use Motul 800 2t at 40:1. Not too much spooge with motul, but there is a bit of spooge. I am guessing it's too rich. I had the bore done and the guy said it had a mad porting job, but I don't know what kind of porting. It does seem to have a lot more bottom end power than most 250. The pipe is stock.
My question is do you need to re - jet for a ported cylinder. If so is it usually leaner or richer or does that depend on the kind of porting. Seeing as it runs so well I don't wanna touch it at the moment, but am just curious.

 

[Studboy]

Try leaning out your pilot jet, it should help with your fouling issues and give you some more response to boot!

 

[crazyYammi]

sounds like a bad crank seal is leaking trans oil into the crankcase

 

[wasted]

if it runs good all through the rpm range you could try the next hotter plug and see if that helps...

 

[uts]

sounds like a bad crank seal is leaking trans oil into the crankcase

Don't think so.The bottom end is fairly new and no loss of tranny oil. Also not the classic clouds of smoke that you see with this problem. Not much smoke at all really.

 

[Studboy]

If you are certain that it isn't the crank seal: 1. Check your reeds, 2. Check your float level 3. Try leaning out your pilot jet.