Removing Secondary Plate and Relocating Stock Air Box Snorkle

I don't think you need any step-by-step instructions to do this.

Take off the airbox; observe how the factory "snorkel" draws air from between the cylinders - ask yourself why Kawi did that; cut a hole in the front side of the airbox in an oval, two circles, or whatever other shape you think looks cool (make sure you understand how the air flows into the airbox and into the intake so you understand where to cut); clean up your mess; reassemble; ride.

Some guys trim the snorkel and put the seal piece around the newly cut hole. I didn't do that as I like the plain open hole in the front of the airbox. You barely notice it. Some others plug the factory hole in the back of the airbox to limit the amount of "hot air" getting into the airbox - I didn't bother with that as I figured the cooler air coming into the newly-cut hole in the front of the airbox had an easier path into the airbox that from the factory hole, meh...whatever.

I did this ghetto-mod myself - the only real noticeable change was hearing the intake a little more.

Well that is cool and all, it will not add X horsepower to the bike. Adding a K&N filter might open up the stock airflow a tad, maybe it'll add a HP or two based on the butt-dyno. You'll likely hear the intake a bit more with the K&N - or not - depending on how much other noise is going on around you.

Do not expect any miracle HP gains by doing this.

I have also done the partial debaffle to my stock pipes, so maybe the happy-meal (of the two mods together) has added 2.2356 HP to the bike - who knows.

Would I do it again? Yup!

You will also finds loads on info in this site about removing those secondaries. Some have removed them, and then re-installed them. Some are running without them. Some haven't bothered to remove them.

I considered this mod (removal of the secondary throttle plates) but decided against it.

Some have said that the removal of these plates makes the roll-on throttle response a little "jerky" or "sudden". If you think about it, at the end of the day these plates do not really restrict the WOT of the VN900, IMHO.

In theory, these secondaries will "richen up" the mixture for a second if one suddenly opens the throttle - as they lag the opening of the primaries by a wee bit - and restrict the incoming air just for a second (maybe less than an actual second). You get the idea.

I have not done the volumetric math in the entire intake tract (or the exhaust for that matter), but the possible volume of air that the bike can use "stock" (how fast the bike can ingest air) is lot likely restricted in the throttle body. I expect the smallest / tightest path of incoming air for the bike is the intake valve opening - although I could be wrong. In any event, in theory, the bike may be able to sneak a couple more CFM of air into the combustion chambers at WOT by the removal of the plates. In a perfect world, one would likely have to remove the shaft that those plates ride on as well, to make the throttle body the perfect shape for the incoming air. I do not know if you can even remove the shaft - I think it has other functions besides holding those secondary plates in place.

Like I said, I have not done this mod as I rarely operate the bike at WOT. And, of course, I do not have aftermarket pipes or intake yet, so the most restrictive part of the entire intake/exhaust tract is not those butterflies.

...just one opinion...

I did the DIY air intake over a year ago and I've been happy with it. When I rev the engine, you can hear the suction.
Plate 6" circle clean out plate from Lowes plumbing section. Includes center screw to attach filter

Acorn nut for center screw, 1/4 chrome w/washer, two 1/4 nuts to solidify post.
Gasket stuff 3/8" weather rubber, one sticky side.
Specter filter red
Specter Air breather hose filter*
*3/8" hose connector for breather hose filter
Blue liquid gasket? Optional. Probably better without it.
1-1/2" hole saw - be sure to clamp down plate, it cut me wicked.

Looks depend on the filter.*
Performance depends on accuracy of holes, seal.*

*Initially I didnt have much of a bend in the crankcase tube and while on a long highway ride at higher rpms, started to get oil spray on my bike. I modified the tube to have an upward bend. I havent had any issues since. *Mileage dropped from the 50 mpg to about 44-46 mpg depending on how much playing I do.*

Start it up
Red FI light should go off
Idle should be 1,000 rpm


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darkarcher said:

Stick a straw in your mouth and take off running. See how long you can breath through that before you pass out.
If your buying the bike to ride two up, or don't care much about performance above 80mph, doing anything to the bike would be silly. It cant get much better for street riding. That's my 2 cents.

Click to expand...

900cc motor, can only draw specified cfm depending upon rpm and operating parameters. stock air tube is designed to furnish appropriate flow and keep it laminar. you may increase flow IF you change parameters such as intake pressure and/or exhaust volume. but just changing the path will not increase the volume.

btw, HP is not what you need for the kind of riding you describe. 2up is same as hauling a load. you need more tork. that is bottom end stuff. spinning motor faster doesnt get you there. It takes a Bigger Motor. with more torque.
that is the issue with 900's. have had plenty. theyr great bikes for solo and ez load work. they top out early and yor always ridding at the top of their output, wanting for more.
Get you a BIG motor that makes more Tork than you will ever need and you will always be in the money in any gear at any rpm at all speeds. the diff is illuminating. but you wont know that till you do it. or keep throwing money at that 900 trying to make it perform. dont take this wrong way, I have a lil 750 I keep trying to ride like a big boys bike.. it aint and never will be.. is why i have my v2k. poncho