changing spark plug how often-400ex

[tom416ex]

how often are you suspose to change the spark plug on a 400ex. I had it jetted about 6 rides ago, was running the balls, now it wont stay running when idiling, i def know its the plug. but how often do they need to be changed? Every few rides or what? Im guessing yes?!?!?!?!?!?!?! Any info would be great....

your jetting is off if you are ruining/fouling plugs...

[rob_990]

i havent changed my plug all summer and its still good.

i know things with spark plugs 20 years old still runnin like new.

Jetting is wrong making the plug foul. And dont jump to thinking its rich it could be both rich and lean at differant throttle positions. Plug should last a long time only needs to be cleaned or changed often when the jetting is wrong or if the engine needs a rebuild which would meen fouling plugs from oil.


Is smoke coming out of exhaust? Black? Blue? White?

[jdboxer02]

If it's smoking it's prolly gonna be black or blue smoke. Black is excess fuel, blue is from oil. White is from water which you shouldn't have since your engine is air cooled.....