opinions and insight on intake mods
 

Hey there, Im very curious to hear what people have done with their intakes. What are the benefits, downfalls, and overall experiences you have had with your mod? First off, I just jetted my stock carb, and installed a FMF powerbomb and twin bros M7, so naturally i took off the airbox lid. The power difference is definitely noticeable, and its LOUD, which i love haha. I have yet to take it off road, and Im a little concerned about going through puddles and whatnot. Don't want to wreck my engine if the box fills up with water, so im open to suggestions haha.

There is a drain in the air box. It wont fill up with water. Before my 351 i ran with the lid on and snorkel removed now with the 351 i have taken the lid off completely. Uni air filter, thats all i have done.

KDX snorkel would be an option.

I have one sitting in a box somewhere... lol

I am at ~1000m (3300ft). I also have the TBR M7 slipon with jet kit. On the intake side I have a Uni filter & snorkel removed which gives me the optimum results. I tried the lid off but it set up a mid-high rev hesitation. It'll be different for each situation. Some folks feel there is too much intake noise with the lid off but if you have an M7, exhaust is all you'll be hearing anyway!

A simple thing that helps both the sound and water issue is to just cut the hole a bit bigger in the airbox lid. You still get the benefit of more air volume, but the sound waves seem to bounce around in the airbox a little better to dampen the sound better than a large-mouthed opening like you have with the lid off. Also this tends to fend off splashed water a little better since the inlet is not a gaping hole like the top of an open glass but more like a box with a hole in it. A hole is a hole, but keeping the edges closed off seems to help with serious water splash. I can tell the difference in the sound with it off or on. It's louder with the lid completely off, and I can only surmise the lid edges are doing a little sound wave redirection at the edges of the top of the box. It's not as effective as a snorkel, but it's not as restrictive as a snorkel. Sound waves are a weird thing, and I guess the wide open airbox is kind of like a megaphone/trumpet as it relates to droning. The lid with the hole just cut bigger seems to cut down on the drone.

Air box lid drilled with a flat bit, between each of the reinforcing ribs. Snorkle removed, backfire screen removed, Uni air filter. Much better throttle response and crisp intake sound. No loud grawl as with lid off.
I live on an Island, 4 degrees off the Equator, it is wet, no it is properly wet here. No problem with water ingress at all.

Yeah, drilling holes in the top would probably yield the same results as mine. In fact I did that to my previous KLR600/650's over the years because the airbox design didn't have a uniform, removable top. Worked great.

The little KLX is proably low-tech enough that the air box is not performing much of a resonant function. Indeed, many of us on this forum have reported performance improvements from modifying our air boxes.
On larger multi-cylinder machines with fuel injection and high redlines however, indiscriminately cutting holes in the air box is unlikely to improve performance. In fact, I have seen cases where a drilled air box top has actually hurt performance to the point of rendering the bike unrideable. Airbox design has evolved well beyond performing simply as an intake splash guard or a sound baffle. They have now become integral to *improving* air flow on many bikes.

Lid on with snorkel removed here. With lid off the intake growl was annoying and honestly I could not tell a difference in performance.

Also tried shortening the snorkel, but that made things worse - filter oil was dripping out.

I believe quite a few inmates here are running KDX snorkels with good results.