In preparation for my 351 and pumper carb that's shipping today , Bill Blue advised me to do the crank case ventilation mod at the airbox and leave the airbox lid on.

Just want to be sure i'm drilling the right place... Anyone got a guide ?

He advised drill a full 1/2 "

Not torn into the bike yet, if its really obvious, then great, if not, then someone please point me in the right direction.

Thanks

 

Video goodness

 

He is certainly right about leaving the airbox lid on - Taking it off lets in sooo much more air that you HAVE to have a proper carb setup (for lidless running) or you'll go waaay lean.. And guess what? There is NO verified safe (Dyno verified) CVK setups for lidless running on a 351.. No one has done the work (yet) to show safe and proper AFR's/setups with such a bike.. Ashame, because making a stock bore suck through the lid costs at least 1 hp and likely costs a 351 much more..

 

buy me a big bore and i'll hook up my AFR gauge

 

re the MrDuhfactor video, Bill Blue said to me, specifically DO NOT drill the crank case, but drill the airbox, which starts off as a 1/2 inch but closes up inside !! but i think i should be able to follow that pipe to the airbox and drill it so that its a 1/2 inch all the way thru.

Edit, actually even Bill Blue has added a comment (as just did I) to that video on YouTube to NOT drill the crankcase but the airbox.

Anyway glad i asked. Hopefully this will help others out doing the mod.

 

The crank case is where the restriction is though. If you look down that hole, half of it is covered on the inside. I'm not sure about other models, but my 09 doesn't have an restriction at the airbox.

I've got a separate filter and hose to re-route it so I don't dump oil into my airbox in the works anyway.

 

Oh man, I been wantin to drill sumpin on my KLX... Drillin that airbox restriction makes a whole lotta common sense - I never thot drillin the crankcase vent was very smart - shavins in de engine and all that - Maybe drill the airbox and get another 1/2 - 1 hp on top ?

 

I sincerely doubt you'd find much of a gain if any one a stock bore 250. If you don't remove the restriction at the crank, it won't matter what you do to the airbox side anyway.

 

CRAP !!! I'll find something else to drill..