Who's running an open airbox?

[mik_str]

First things first: Happy New Year to everyone!!!!

Roger D. recommended I run an open airbox in my VTR (sawing the top of the lid and leaving a 5-10mm lp all around to hold down the filter). As most of you are on the same island as the man himself and quite a few of you have had the privilege of dealing with him in person, I was wondering how many of you are running this airbox mod on your Storms?

Also, what kind of gains did you get and what jetting changes were needed?

thanks in advance

[benny hedges]

hi mik - gretings to you too!

have a look at this link, as it explains the mod roger has told you about.
http://www.ablett.jp/bikes/vtr/air_box_lid.htm

this guy didnt go all the way with the jetting and didnt get the results he expected, but when i took my bike here for a fuelling run http://www.junction-33.com/ (next door unit to roger's place) the operator (andy) told me he does all the dyno work for roger and they have done a lot with the airbox mod, with massive gains to be had.

regarding the jetting, he didnt give any specific jetting sizes but said it requires 'extensive modding to a stage 2 dyno kit' and a bmc race filter (which i have)
i take from this he uses bigger pilots, different nedles and larger main jets.
as said elsewhere, dont fit the lighter springs from the stage 2 kit though as it messes up the lift on the diaphragm & fks up the mix)

i think it will be worth you speaking further with roger & andy at the dyno centre about this.
all his dyno runs are saved on computer so im sure he will pull a few moriwaki vtr bikes for you and see what jetting was used - like roger he is a very helpfull guy, plus i'd imagine this time of year he's fairly quiet workwise.

one thing though, when i had the over-rich issues with mine i ran it on trial without the airbox lid & just gaffer taped the filter on and the noise is bloody awfull lol, louder than the art cans i was running.
i decided instead to mod an airbox to leave just the velocity stack mounts and cut them down to leave a 48mm tube sticking out, then mount a pair of k&n bellmouth filters directly to the carbs, attached to the tubes, essentially doing away with the entire airbox.

good luck with this mik - obviously i would be interested in what gains you get.

[mik_str]

Thanks Benny

I am indeed picking Roger's brain on this one (via e-mail). What a great and helpful chap. The world needs more Rogers!

Will keep you posted on my results (nothing concrete until Spring, however, I am in Canada after all, and it's snowmobiling season here, lol)

cheers

[benny hedges]

lookin at the dyno results in that link to the airbox mod, i think the guy had a bad engine to start with, plus notice there is no fuelling graph...
and his results do not improve (or get worse) as he ups the main jet size.
without the fuelling graph you would think it's running lean - like i did with mine, but the fuelling curve showed over-lean off tickover indicating it needed larger pilots, then a massive drop under the line showing it was way too rich at all rpm up to 8k+

i think with the increased airflow this mod gives, he would've been better trying smaller mains rather than bigger.
can't see how the dyno operator wouldve missed that tbh, but if you just ask for a power run thats all you will get!

wonder if he still has his mori stacks & airbox lid!

when i spoke to dyno andy, he mentioned dialling in the cams ive got and doing a few runs for best results...
i think i'll go for that tbh after ive fitted 11.5 pistons and cleaned up the heads a bit. (and saved up lol!)

cant wait to see tony's dyno runs

[tony.mon]

I'm playing with this one at the moment as well.
Have a look at the "Airbox modding" thread a couple of weeks back.

Iv'e merely improved the airbox volume by removing the two corner filter housings, and the large pipes and catchtank that normally fits in the airbox- can't be good for laminar flows, eddy currents etc.
(Haven't tried it on the bike yet; that's later in the dyno testing program after cams).

But now the top section looks proportionally smaller, and I'm not sure that there's enough volume to get sufficient air into the top section so that the filter has a good supply of air at positive pressure across the whole filter area.
Particularly after the fornt intake has sucked everything it can in during that part of the cycle.
So I was playing with the idea of leaving the front intake alone and adding two smaller diameter (perhaps 20mm ID) tubes over the rear intake, fed from the front intake triangular holes in the fairing.
I'll have to check carefully, but I think that there's enough space between the tank and the airbox lid to do this.

If not, then I'm aiming at the (Moriwaki?) solution of doing away with the airbox lid and sealing against the underside of the tank, maximising space.

Lastly I considered adding an additional small area of filter in the unused part of the filter plate, to increase air throughput.

[benny hedges]

Lastly I considered adding an additional small are of filter in the unused part of the filter plate, to increase air throughput.

yeh ive always thought it odd that the std & k&n filter only uses a 5" square of filter.... surely it would make a massive difference if the entire area of the airbox was all filter?
like the one on the zx is a 10" oval of washable foam.... might be worth fabbing something up, maybe use 2 old filters, cut out the pleats and sandwich a mesh & foam element between them?

[mik_str]

The Pipercross is all filter

[benny hedges]

bmc ive got is same

[Karl_h]

Are the pipercross filters any good?

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