Spark Plug and Jetting

[Zacharus]

2005 kdx200 - What is the stock jetting ?

pulled snorkel and put on gnarly desert pipe. stock plug, and jetting. (pulled plug before putting on pipe, black and oily)

ran bike, seemed fine, but i think it could be better.

My neighbor says to run a hotter plug. stock is BR8ES
so i should go to a BR7ES, or a BR7EIX. (live in tucson, arizona ,elevation is 2200 feet above sea level temps around 40 F to 80 F)

if i put on the 7, will that clear things up and make it run better, or do i have to screw around with jets and needles ?

what will i need to do to get the best running efficiency?

Thanks

 

[adam728]

Jet it properly, don't try and hide a problem by throwing different plugs in it.

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

You'll find your jetting recomendations. It's easy to do. If you can take the carb off the bike you can rejet it.

 

[Zacharus]

ok so jet it, but i still need to put a hotter plug in during winter, then go back to a 8 or 9 when it gets hot out again during the summer right ?

 

[ridejunky]

Not necessarily, Usually when the ambient temp is colder the air caries more oxygen thus causing a somewhat leaner condition so running a hotter plug in winter and colder in summer is counter productive. I would follow adam728"s advice.

 

[Rhodester]

Unless they've changed it recently your main is a 160, and pilot is a 48. You'll probably be in the ball park with 155 and 42 or 45 pilot. With aftermarket reed block probably a 152 main and 42 pilot to be close and still safe IN WARM WEATHER. Under 65 degrees go up 1 size on the main. In the low 50s maybe another 1 size up. Down at 40 degrees you might be close with stock jetting.

 

[adam728]

ok so jet it, but i still need to put a hotter plug in during winter, then go back to a 8 or 9 when it gets hot out again during the summer right ?

I've never changed heat ranges for the outside temperature, just jetting. Being that I lived in Michigan my whole life and spent a few year riding all year round, that means ranges from about 0 degrees to 95+ degrees, only jetting changes.

 

[KDXMAC]

how long is a piece of string........................

 

[G. Gearloose]

if i put on the 7, will that clear things up and make it run better

nope.

 

[johnnymoto]

My kdx ran good but when I went to a "7" plug, the bottom end power jumped up big time. I run a ram valve and pro circuit pipe. I Like adam 728 said go to the kdx jetting page to get some good baseline starting points.

 

[Rhodester]

The only reason I'd change to a hotter plug is if my jetting was pretty close (but still on the safe side, ie. barely rich) and I had the insulator (main part of it including the tip) on the medium to dark side of things. That coloration on that part of the plug would indicate to me that my riding style was sedate enough to warrant a hotter heat range to clean things up. Please note, however, that I wouldn't be reading this area of the plug for determining my jetting. I'd be using the ring at the extreme base of the plug insulator for that. I don't jet by plug heat range. Another color might also show up in the tip area of the plug if I'm using pump gas (which I do). I'd get a brown or reddish brown color. That indicates additives in the pump gas. I wouldn't be concerned about that. If I ride aggressively enough the main body of the insulator will be fairly white (or light colored). Again, that area of the plug is not the proper indicator of your jetting unless (perhaps) you are way off in the woods somewhere in the jetting department. Get a new plug and do a proper plug chop test for jetting.