32 mk2 amals

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Interesting discussion. I have just acquired a 1972 750 with a Combat engine. It has been sitting neglected for a number of years and I am just beginning the process of bring it back to life. I am rebuilding the Amal 932 carbs and I find that the have 200 size main jets and 107 size needle jets. The bike is an "S" model with side pipes and reverse cone mufflers and it had a K&N air filter on it when I got it. The needles were in the middle position. Any idea why the main jets were so much smaller than stock? Please enlighten me as I am rather ignorant about carburetor jet sizes. I assume that a size 200 main is smaller than a size 230 or 240. Any ideas what the number refer to? Likewise that 107 needle jets that I have are most likely slightly larger than the 106 jets mentioned above.
https://amalcarb.co.uk/main-jet-size-200.html "The number e.g. 100 indicates that it will flow 100cc`s of fuel in one minute at a specified head. "
107 Needle jets were spec'd for 1970.
200 Mains sound small, more so with 10% Ethanol. But if the plugs look good...
 

L.A.B.

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I have just acquired a 1972 750 with a Combat engine...


...The bike is an "S" model with side pipes and reverse cone mufflers and it had a K&N air filter on it when I got it.


What you have is a 1972 Combat Roadster fitted with an 'S' type exhaust system as the 'S' was discontinued during 1970.

Any idea why the main jets were so much smaller than stock?

If they are original 'S' type silencers/mufflers with baffle plates then that might explain it.
 
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What you have is a 1972 Combat Roadster fitted with an 'S' type exhaust system as the 'S' was discontinued during 1970.



If they are original 'S' type silencers/mufflers with baffle plates then that might explain it.
Okay, then riddle me this, please: Besides the side pipes was there any difference between a standard Roadster and an "S" model?
 

L.A.B.

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Okay, then riddle me this, please: Besides the side pipes was there any difference between a standard Roadster and an "S" model?

Do you mean to a 1972 Combat Roadster?
The main differences were the 'S' type had a standard engine (with a 20M3S engine number prefix), 30mm carbs, not Combat, a central oil tank and right-hand battery access side panel (due to the LH side S exhaust), a closer fitting front mudguard/fender and 3.00 section tyre to clear the exhaust pipes on full fork compression, a frame mounted centre stand, different side stand, 'halo' style headlamp bracket. More angular side panels, two-position ignition switch set into the LH panel, different electrics, single (Wipac Triconsul) handlebar switch cluster on the LH side.

Edit: 1972 (2xxxxx series) was the first 'year' to have the disc brake so an 'S' would've had the drum front brake.
 
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