32 mk2 amals

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shredne said:
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.
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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...
 
shredne said:
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.
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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.

shredne said:
Any idea why the main jets were so much smaller than stock?
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If they are original 'S' type silencers/mufflers with baffle plates then that might explain it.
 
L.A.B. said:
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.
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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?
 
shredne said:
Okay, then riddle me this, please: Besides the side pipes was there any difference between a standard Roadster and an "S" model?
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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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