My 02 315 has an NGK BPR6EIX iridium plug. Took a look at it yesterday, and there's a little oily soot around the end of the threaded base. The tip of the grounding electrode was dry and dark brown. Is this normal? Need a hotter plug, or leaner jetting? Since it's ridden slow and easy a lot would turning in the mixture screw help keep the plug clean?

Bike is ridden easy most of the time around private property, but on each ride I do open it up for a few seconds on some flat areas. Timing has been retarded a tad and carb has 35 pilot jet, 110 main jet, D37 needle at 2nd from bottom slot. Using 80:1 mix with Silkolene.

How does the bike perform in your opinion?

Does it foul the plug?

If it isn't broke you might not want to fix it. Too rich is better than too lean. I don't have any experience with Montesa or trials bike jetting, but my guess would be your pilot is a little rich, or the needle taper for your riding style is a little rich.

My '04 has soot fouled the 6 heat range plug twice in the 6 weeks I've owned it, I ride in a small area so I don't get a chance to really clean it out. The performance off the bottom is good, so I'll live with the occational fouling. The fouling occured with 92 octane fuel, I just switched to 98 octane blend which may resolve the problem. Ran the first tank through it last night and there is a worth while increase throttle response and a definate decrease in the decel pinging which quiet's the exhaust note. Next gas run I'll blend to 100 octane.

My fuel screw is 2 3/4 turns out, the temp is 70* F, medium humidity, altitude is 440'.

That plug/bike is fine.

The insulator is all you need to look at.

Don't go looking for trouble...go for a ride!

Thanks all.

This is the first 2 stroke I've owned, so it just looks bad compared to the 4 stroke plugs I've looked at. BTW, it has not fouled yet, and starts fine.