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i just replaced the sad melted air box in my 2009 250s. (351) with a new box for a 2014 KLX250s... just noticed these air in ports... there are two whereas the old box just had one. What’s up with that?
More specs... sorry. FMF Q4 on a 351 with the Mikuni 33/34 From BIll Blue. I’m just wondering which snorkel should I start with... thanks.
Last edited by Dragon351; Sep 16, 2018 at 08:54 PM.
two snorkels to chose from... the bike has decel pop. The old box had a leak that could have influences the air/fuel mix. Had it in a shop that said about the popping, “get used to it”. I replaced the box, made hangers for the muffler to get it away from the new air box, wrapped the pipe in that titanium exhaust tape, and was about to reassemble when I noticed the difference in the lid and the extra intake. This pic shows old at bottom, New in bike (top)
Last edited by Dragon351; Sep 16, 2018 at 09:02 PM.
Look at the size of the snorkel openings. The one on the top is the stock KLX250 snorkel, the bottom is the KDX snorkel, which is about twice the area opening. Much more open breathing, I measured and it is also within a small amount the same size as the air boot connecting the air box to the carburetor - much more open breathing. If it fits through the air boot it fits through the snorkel. Not so true with the stock one.
If you're doing only street or dry conditions you can leave off the lid. If there is the possibility of getting water in on the filter the lower lid is the one you want.
As for decel popping usually called crackle because of the crackling sound, it is just the closed throttle leanness and it is not harmful or some flaw in jetting per Mikuni. You only need be concerned if you have serious bang noise like a firecracker going off. That is usually from too lean of mix.
But if you want to do so you can richen up the idle mix to take some of it away. I personally didn't bother. My idle mix is right so I don't care if it crackles with the throttle off on decel.. Your choice. Do or don't, no harm either way.
Weird. The bottom one is the lid that was on the bike when I got it last spring. The top one with the longer and narrower snorkle came in an airbox I got off eBay that was supposed to be a KLX250S 2014.
I got more google to do. And YouTuberin’
Last edited by Dragon351; Sep 16, 2018 at 11:06 PM.
Two different air boxes
