Under tank filter

Kyrocket

.040 Over
Joined
Jul 24, 2013
Messages
72
Location
Kentucky
Is this still a viable option? I don't want to do the triple filter mod. Looking to do this mod. My one question is what is the deal with the little filter in the original pics in the sticky? How do you keep unfiltered air from coming through the air box under the seat and into the motor? I might just be missing something...
 
If you do the under tank mod - and there's no reason not to unless you have a "T" as it wont fit, then:-----

FORGET what's under the seat. There are some weird rubber bits that connect the underseat box to the inner "grey" plenum. You remove this and fit a filter directly to the rear of the plenum.



The little filter is probably the crank case breather filter - it's recommended if you intend to use the box under the seat for something else.

The major reason to do the undertank is to free up the filter box to put things in. Otherwise I'm not that sure there's MUCH benefit. There is some - but it's NOT a lot.

Unless the new RAMAIR filters are as good as I hope - I'll be refitting the above.
 
This is how it looks installed under tank. Remove all the plastic stuff not needed which previously connected the plenum to the filter. Crankcase breather filter just goes on in place of the hose. Pretty straight forward.
 

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The main drawback with this (apart from not achieving anything signifivcant for your $) is that the filter will be sitting above the engine and drawing in relatively warmer air than would be coming in from behind the seat. It does free up space under the seat but you're still left with the main plenum and the same poor access to the throttle bodies - and a monster pain in the arse if you even take the plenum off and need to put it back on. Looks simple, but it's NOT.

And yes, you will need to put a small filter on the crankcase breather.
 
KYRocket, I've just seen that there is a sister thread going on about this under tank filter which will address your questions. I, for one, find it a much better option than trying to "draw" air thru narrow snorkels and from, of all things, a rear facing. I "felt" the difference, gained some under key storage, and it is no louder than before i.e. no crickets from triple K&N's. Worked for me. Keeping my eye on the new Ramair as well.
 
The main drawback with this is that the filter will be sitting above the engine and drawing in relatively warmer air than would be coming in from behind the seat.
Well you'd think that BUT I think the biggest difference twixt this and the triples comes from the two restrictive ovals between the two plenums.

2300ccs at 3000rpms are drawing in 57.5 litres of air a SECOND. In a water jacketed engine the chances of the engine heat raising that quantity of air by a significant amount is negligible. Ambient air temps will have far more effect.

Wayne pointed out that there is hot air coming of the radiator and tbh - that's more of an issue then the filter under the tank. That air is hotter and needs to be deflected away from the filters. One of these days I must get some temp gauges to prove this.

So far my tests with the home modified OUTER plenum, which is still a bit of a pig to get on and off (actually worse due to all the heat/sound insulation)- shows better breathing than with triple K&N's. Far more consistent - and far better low end MUCH smoother.



As for plenum removing. The outer is a pig - the inner takes seconds.
 
I didn't mention triples. All I said was that the air under the tank is going to be relatively warmer than the air behind the seat ie where the stock intake draws from.
 
I didn't mention triples. All I said was that the air under the tank is going to be relatively warmer than the air behind the seat ie where the stock intake draws from.
True but it's also less restricted air.

I'd also be interested to see pressure flow data caused by turbulence from legs, screens etc

The under seat snorkels are also easily blocked by jackets/jeans - I have that T-Shirt - well OK my wife does as they were her jeans.

Finger's crossed that Ramair have filters ready for me in a fortnight, when I'm in the UK.
 
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