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If you mean the grey round vacuum actuator on the back of the air box it
seems to be to do with noise reduction, it closes a flap under certain
conditions and forces the bike to breath through the snorkel, bikes
in some markets don't have it and the snorkel is turned 180 degrees.
seems to be to do with noise reduction, it closes a flap under certain
conditions and forces the bike to breath through the snorkel, bikes
in some markets don't have it and the snorkel is turned 180 degrees.
Good question and I don't know, looked in the service book and saw nothing there though I will
look again as there must be something about it, with the engine running you can feel air going
in the back just under the actuator and you can feel the flap and move it but it does not seem
to move when the engine is rev'd, it's controlled by the ECU trough a unit under the right of the
tank and gets it's vacuum from the right throttle body and as a small surge tank connected so
quit a complicated bit of kit.
look again as there must be something about it, with the engine running you can feel air going
in the back just under the actuator and you can feel the flap and move it but it does not seem
to move when the engine is rev'd, it's controlled by the ECU trough a unit under the right of the
tank and gets it's vacuum from the right throttle body and as a small surge tank connected so
quit a complicated bit of kit.
It's all here Ralph thanks for your help.
ROGUE RC51 Flapper Valve Mod Page
ROGUE RC51 Flapper Valve Mod Page
I noticed that the airbox valve operates on vacuum.
This is (probably) done for 2 things:
- Air intake noise (a pretty obvious reason, since emission/sound laws are getting tighter.)
- Intake air speed: not sure about it, but it's a very logical explanation:
A smaller intake hole will give less air, but at a MUCH higher rate, thus in theory giving more torque and economy at mainly low rpm.
It can be compared to Honda's variable intake length system: high intake resistance at low rpms and lower resistance at high rpms.
However, the stock airbox MIGHT be a bit restrictive at high rpm and then you come to a point to what the rider wants...
If you'd want the most out of it, you'd need a custom fuel commander, a DNA stage 1 & 2 filter and a free flowing exhaust.
You'd get maximum power, noise and a worse fuel economy, this can give a very nice increase in power and most people find it a good investment if you just want a bit more 'oomph'.
If you'd just want maximum torque at real low rpm's and don't care about horsepower, just leave it as is...
Regards,
Dutchman