1974 MK2a mufflers for USA

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jamesp

jamesp

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Hello, I am restoring a 1974 MK2a, built in August of 1974 for the U.S. I was wondering if it originally came with the black cap mufflers or pea shooters? Thanks for your help.
 
If it is a genuine 2A model (with the black plastic airbox) then it would have had the black caps.
 
I think Black cap mufflers and plastic air box came to the USA with the '75 E start.
Late '74 MK2a's in the states held off on those "noise limiters" (me thinks) as I've never seen in 35 years the black caps and plastic filter housings on anythin but an e.start here.

JD
 
jeffdavison said:
I think Black cap mufflers and plastic air box came to the USA with the '75 E start. Late '74 MK2a's in the states held off on those "noise limiters" (me thinks) as I've never seen in 35 years the black caps and plastic filter housings on anythin but an e.start here.
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I wouldn't be an A model if it did not have those parts.

Mk 1A and 2A models certainly had the black caps and black plastic airbox as standard because both items were part of the noise reduction package primarily intended for the European market, however the 850 Mk 2 model with peashooters and perforated metal airbox still continued to be produced during 1974 for the US market. Therefore Mk2 and 2A must be regarded as two different models.
 
I have a late '74 here in the US. Definately A MK2, but it also has the "sealed for life" swing arm bushings. It had the peashooters and the perf metal airbox.


JD
 
I have seen the MK2 A here in the states and it DID have the plastic air box and bean cans.
 
I have seen a long discussion on another site about 5 - 8 years ago and the conclusion was that the USa had both Mk 11 and Mk 11a at the same time. It was also suggested it could have been a West Coast, East Coast thing but even that was confused.
 
jeffdavison said:
I have a late '74 here in the US. Definately A MK2, but it also has the "sealed for life" swing arm bushings. It had the peashooters and the perf metal airbox.


JD
Click to expand...

That's how mine is, and I've had it from new. Built 8/74. Of course it also had crossover head pipes.
 
From what I have learned, it seems the Mk2a came with the black cap mufflers.
 
Mk 11a - black cap bean can mufflers and plastic airbox

Mk11 - peashooter mufflers and metal airbox

But they both came to the USA in 1974.

So unless you know by some other means that your bike was originally a Mk 11a style then you will be correct for a 1974 USA specification bike no matter which option you choose.

If you wonder why a NZer knows this it is because I own a NZ new July built 1974 850 Roadster and for a long time I thought it was an Mk11 a - turns out it was really a USA style Mk 11. I had detailed correspondance with Dave Comeau who knows a very great deal about the details of US model Commandos. He told me he had seen examples of both types in the US over the years.
 
Case for 850MkIIa and MkII in the US - all '74 JPNs have bean can mufflers and plastic air boxes. Many 850 MkII roadsters around with peashooters and ham can air boxes.

1974 MK2a mufflers for USA
 
I wonder if this is really a (US) Mk2A sometimes even with the plastic airbox.
It has a very early build date of 12/73 - 311032.

1974 MK2a mufflers for USA
 
Another way to spot if a bike has been converted from 'A' spec is the battery carrier is different, and the LH sidepanel is retained by a plastic Dzus fastener. I don't know if this set-up would accomodate the ham-can airbox - I'd be interested to know if anyone has done this?
They also have a tall 2nd gear which really lets you know it's there when changing down - made worse by the 22T gearbox sprocket.
As already alluded to, it was all done to pass emissions regs, including the taller 2nd gear.

I believe the JPN reps were all MkIIAs?
One just went on UK ebay for an eye-watering fourteen thousand of our Great British Pounds - lordy!
 
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