Black box conversion to open element K+N air cleaner

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I had dyno'd my relatively stock MK3 last October with a black box, no venturis, unbalanced pipes and peashooters. 260 mains 19 pilots running rich at bottom of the ideal band, compression plate fitted, and it was kicking out nearly 49 horses.
If you remove the black box, don't destroy or damage it, they are expensive secondhand.
I have since removed the compression plate and dropped the needle one notch to the top groove which has transformed the performance.
Other than access to the slides I'm not sure that you will gain anything else.
To always know where your slides are, with carbs removed put slide in body onto stops measure depth of slide from top of body with depth gauge or tail of a vernier, set the other side the same height and lightly scratch stop screw to body for reference. If you do this with the stop screw flush to recess on carb body on the Premier you will not be far out and have position to work from or go back to without removing the carb rubbers.
 
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Neither of those are a snorkel though...Even the AN parts break down page calls it a 'Air-intake venturi which normally is a device to increase velocity in that case or worse a removable restrictor to quiet the inlet noise at testing.

I would be very surprised if there is a Norton out there with those 'things still in place Mk1/2a / Mk3. :D

p400 said:
What part is the snorkle?
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Time Warp said:
The parts that look like snorkels but they are part of the air box body, there was some insert in the inlet of the snorkel from new ?
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Yes, Still seen on some of the lower mileage bikes, not normally both though as one has usually fallen out at time / ride unknown. There was a clip that was made to hold them in, not seen these fitted though.

Do not cut off the intake ears on either side of the box - fit a K&N unelss you like destroying big bucks.
 
Black box conversion to open element K+N air cleaner
 
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Madnorton said:
I had dyno'd my relatively stock MK3 last October with a black box, no venturis, unbalanced pipes and peashooters. 260 mains 19 pilots running rich at bottom of the ideal band, compression plate fitted, and it was kicking out nearly 49 horses.
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Quite impressive! :)
 
p400 said:
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P400 asked " What part do you remove..."

Just remove the rubber item, #12.
My bike had them still fitted until recently.
I can't honestly say that I've noticed a difference. It was a strong runner before.

One simple mod that did give it a noticeable amount of extra grunt was changing from a thick copper head gasket to thin composite.

Glen
 
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Time Warp said:
The parts that look like snorkels but they are part of the air box body, there was some insert in the inlet of the snorkel from new ?

I see no reason to wreck the air box by cutting those off, the plastic box was a step in the right direction (Even if true it was a noise control at introduction) as far as a still air box and if need be could be modified in a more humane way for increased flow if that was shown to be an improvement.
It could have the bottom section or rear portion modified/opened below the filter element.

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What about the Mk2a east/west battery tray and the 'ham can ?
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Yes, there were rubber inserts in the snorkels from new. I still have mine. I don't think anyone suggested cutting off the plastic snorkels. I do have an extra metal plate that holds in the air filter that could be modified to let in more air. Maybe like a "ram air" affect? LOL.
 
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