1974 MK2A Air Box Schematic - Tray Style

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MCP

MCP

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I am looking for a schematic for the newer style air box that accepts the foam tray style filter. If someone could link that it would be very much appreciated.
 
If you have a Mk 3 and want to have a "correct" OEM example, I am all for it! If you are wanting to
"upgrade" a prior year example, then there are numerous problems to be overcome which is why the
majority of USA examples of a Mk2A/ Mk3 have been modified to remove this airbox. No offense intended.
This airbag was designed solely for noise reduction as required by European and USA governments. It
did not enhance anything, but rather inhibited performance. That said, if I had a Mk3, I would want to
restore it to original.
 
Link me to the dyno shoot out showing the plastic air box with peashooters costs HP (or torque ?) please.

The only thing I would say regarding that box is take the time to make sure the filter is sealed in the groove and at the front panel face.

Fantastic compared to that tin thing.
1974 MK2A Air Box Schematic - Tray Style
 
Thanks for the info, I didnt know that, and no offense taken, I was just curious.

Interesting, because I bought my Norton (MK2A) new in 1974 in London UK, and it came with that air box. I doubt that it was meant for export, it just happened to be one of the few left on the floor when I bought it.


I was happy with the performance then, and considering I'm a lot longer in the tooth now; pretty sure I wouldnt notice the difference if I swapped it out.

Thanks again, for the feedback.

lazyeye6 said:
If you have a Mk 3 and want to have a "correct" OEM example, I am all for it! If you are wanting to
"upgrade" a prior year example, then there are numerous problems to be overcome which is why the
majority of USA examples of a Mk2A/ Mk3 have been modified to remove this airbox. No offense intended.
This airbag was designed solely for noise reduction as required by European and USA governments. It
did not enhance anything, but rather inhibited performance. That said, if I had a Mk3, I would want to
restore it to original.
Click to expand...
 
The box makes it hard to synchronize the throttle cables for a smooth off idle transition from a dead.
 
Time Warp said:
Link me to the dyno shoot out showing the plastic air box with peashooters costs HP (or torque ?) please.
Click to expand...
Not quite a shoot out, but a quote from the John Hudson notes posted in another thread:

“What did restrict performance was the black plastic air box, remove this for a 750 type one to gain performance”.
 
My MK2a still has the black box but with peashooters and the black box is minus the snorkels. If its down on MK2 performance then its news to me, why is it that I had to fit 260 main as per the MK2 to get the peashooters to perform. IMHO the performance on the MK2a reduction is down to the black cap silencers and the snorkels.
 
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The single snorkel intake on a Kawasaki H2 750 airbox would be around the size of one on the Norton.
They would little different to the stock (separate) air boxes on Ducati's of the same period.

Air filter area might be smaller on the Norton, perhaps it could have been mounted on an angle to enlarge that but are becoming rare so chopping one up is less of an option these days.
It would not surprise me if the plastic airbox was better for roll on 'grunt due to some form of harmonic or other can't be measured thing.
 
Those rubber snorkel things were thankfully easy to remove.
Worth noting that the Mk2A and Mk 3 had very different installations, primarily due to the difference in side panel and ignition barrel mountings. Breather pipe locations differ too, so while they look similar, they won't fit.
Mk2A ones seem to be getting valuable now, possibly because of all the JPN replicas being built?
 
It would not surprise me if the snorkel 'air intake venturis were the restriction and meant to be unofficially removed at the dealership.
 
Personally I would also be surprised if the black box impeded performance.

An air box is supposed to aid roll on grunt as TW says due, in part, to it acting as a plenum chamber of still air IIRC.
 
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MCP said:
Interesting, because I bought my Norton (MK2A) new in 1974 in London UK, and it came with that air box. I doubt that it was meant for export, it just happened to be one of the few left on the floor when I bought it.
Click to expand...

Is it close to 311032 ?
 
MCP said:
Interesting, because I bought my Norton (MK2A) new in 1974 in London UK, and it came with that air box. I doubt that it was meant for export, it just happened to be one of the few left on the floor when I bought it.
Click to expand...
My bike was purchased at Elite Motors, London in September 74 and has the same airbox.
 
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