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Discussion Starter #1
Having purchased a second hand airbox from ebay, I have decided to try and get a little more from the stock unit as opposed to purchasing and aftermarket example. After reviewing the standard set up it really has you wondering about exactly what arrangement they had in Edward's bike. The vents in the frame are top notch whilst the snorkel and airbox are compromised. It would appear that they didn't have a filter after the frame. The frame makes wonderful use of the Coanda effect which would be lost if the air was filtered afterwards. The stock box ruins this. The tapered and assymetrical nature of the box also lends itself to filling the rear cylinder if the filters and baffle weren't there. The forward cylinder is shrouded. I am also surprised at the lack of heat shielding on the box as well as no mat between the engine and airbox. I have already begun machining up new velocity stacks out of acetal that will allow me to test the compatability of varying lengths. I will fabricate a new snorkel out of aluminium sheet that will improve flow and provide room for a filter and air laminiser prior to flowing through the frame. I know many ideas have been tried before.....hopefully a set of fresh eyes may be of some benefit.
 

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Discussion Starter #3
Nice velocity stacks.
I am surprised the heat shielding is on the inside of the lid of the box.
One thing that is interesting with all three of the stock boxes I have is that there is oil on all of the internal sensors. Obviously the crankcase breather is the culprit here and will be messing with the data. Re-routing the breather through its own catch tank and then to atmosphere will benefit. Alternatively, Routing the crankcase breather through the pair system and out the exhaust is usually good for a couple of HP as well.
 

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Discussion Starter #6
The frame has been really well designed to account for pressure fill inside the box. Clearly the performance will be improved by having the filter before the air passes through the frame.
 

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Works air box & TB's

It would be nice if this airbox could be replicated without the need for thermostat removal (and ETI fuel tank compatible).
Plus a replaceable commonly used filter element easily accessable inside the airbox.
This is what I've been waiting for for years.
 

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Discussion Starter #9
I hear what you are saying about the air filter. I would like to incorporate a "slide in" filter cartridge within the snorkel. It would simply be a case of reaching up below the snorkel and releasing a couple of thumb screws to service the filter. No tools required. The box on my first bike has BMC filters in it. There is plenty of material in just one of those to unfurl and create the heart of the cartridge.
 

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Discussion Starter #10
JB
I have made a second pair of velocity stacks for the other bike. Given that the other bike has extremely low miles I would be inclined to use it sparingly and perhaps keep it original. Once I have settled on the right heights for the stacks I will make them the same and you are most welcome to the other set. I am guessing the stock heights will work best. No doubt Honda have done their homework here.
The ones in the pictures are fresh off the mill and still need a little tidying up. They will be a lot nicer once finished as well as lighter. I will start on the snorkel next week. After checking my stocks I only have 1/8" sheet aluminium. Needs to be 1/16".
 

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It would be nice if this airbox could be replicated without the need for thermostat removal (and ETI fuel tank compatible).
Plus a replaceable commonly used filter element easily accessable inside the airbox.
This is what I've been waiting for for years.
This airbox will not fit the OEM or any tank for that matter... other then the HRC tank. I know as I have an HRC works airbox here and have tried it on the ETI, Sebimoto, Beater and OEM tanks.
As for what you have been waiting for @SubSailor... I have the molds ready now for producing a lidded airbox without need for thermostat relocating.
I will be constructing one for use in my build over the coming months.
 

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Discussion Starter #12
Duck hunter
I don't think relocating the sensor would be such a bad thing. All 3 of my stock air boxes show an oil patch on the lid as well as on the sensor. I will be rerouting the case breather into the tail section and through a labrynth before it either vents to atmoshpere or back into the box.
 

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Discussion Starter #13
Went back to back with the modified airbox and the stock unit. A marked improvement overall but clearly too lean. Popping on decel everywhere. Added fuel and things got even better. Enough guesswork. Time for a proper tune.
 

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what did you use for a filter when you tested your modded box? if you didn't have one, did you remove the filters from your oem box to make it an even playing field?
 

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Discussion Starter #16
There were no filters in the stock box. I wanted to test the boxes by themselves. I cut up a motocross filter and simply sandwiched it between the the union in the snorkel. Just in front of where the flapper valve used to be and the section that holds the screen. This best represents the area as to where I will ultimately house my filter.
 

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Discussion Starter #17
Went for another run this afternoon. The bike feels smoother all over but builds revs much easier in the upper range. There is a hill near our place which is great for testing. The modded box allows the bike to climb with more gusto at 80 mph and above than the stocker. You can tell that the fuelling is in need of tuning but still.....a hell of a lot of fun.
Between the exhaust mods and the box I have outlayed around $90 and a bit of time. Pretty happy so far.
The cams can wait till after Christmas. Pick up the aluminium sheet tomorrow for the snorkel.

JB
PM me your address and I will send you the other stacks. Keep your standard box and pick one up off ebay. They're dirt cheap.
 
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