Anyone know what PCV fits? I live too far away from an auto parts store that speaks english, so I would appreciate a part number or vehicle application that fits, so I could order online.

 

True dat.....the rest is hogwash......why mod your setup for 1/1000 of a hp gain, stupid in my opinion. The klx is not a race bike and you will never notice the difference...nor will you on a ktm450 btw. Crankcase pressure, gmafb....the only thing that is good about the pcv valve is that it minimizes entrainment of outside dirt into the case.

Please folks, use that money to save for a bore or carb or sumthin.

 

I can speak for a fact that boring out the vent hole going into the airbox helped my bike rev more (as well as air injection removal). But I'm not into rerouting up into the airbox. Theres enough hoses on this thing already.
________
Honda ST1100

 

Any powercyclinder produces a fair amount of blow-by. Theses gases go into the crankcase producing a nominal postive pressure. Also with the discplacement changes inside the crankcase you get pumping action. A outlet is needed to relieve the pressure or you will push the oil right out the gaskets. If you have just a plain open vent w/o a minimum restriction, you will have major oil carry-over into the airbox. Many different types of valves are used in breathing system from a umbrella to spring steel to ball check valves. The purpose is to maintain a nominal "negative" pressure inside the crankacase cavity and also to keep the oil inside the engine. The valve must be sized to the engine speed and amount of volume passing through the breather system in order to work correctly.
Kawasaki approach solving this problem economically was to have a reducer (in the air box)
That most of you drill out. Any ole breather from a automotive engine won't get the job done.

 

Great posts!
Nothing like being talked down to.

 

For those looking for a cheaper alternative to the one in the video I posted, you might try KTM part number 60030090344. This is a 1-way valve off a KTM 950. It is item #40 in this parts diagram:



Not sure how much it's going to help on a 250, but KTM apparently thought it was beneficial for the '09 SE.