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March 29 2024 [New Zealand] 
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Benjamin Gradler
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Someone just told me that a short-stroke 500 Manx runs better with a 1 3/8" G.P. Than with the original 1 1/2" G.P.. Is this just an old wives tail or is there something to it? Anyone have any experience trying different carburetors on their late Manx? Thanks....
 
Benjamin Gradler
(read 29596 times)
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Anyway, the Manx I bought came with a 1 1/2 GP and a Gardner carb, and now I see neither is original to the bike as I found out it came with a 1 3/8 long body GP carb. I know that usually the larger the carb, when properly set up will move your peak power up in the rpm range a bit at the expense of mid-range torque. So maybe I can sell or trade the larger GP and end up with the right carb for the bike. Back in the day, a good rider probably would go with a larger carb, cams or whatever might give him more power. Now, when most original Manx Nortons are either more of a collectors item or not being revved to the limit every week by a Mike Hailwood or Bob McIntyre, the smaller original spec carb makes sense, especially to a poor and slow rider like me.....
 
Ken McIntosh
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The 1961-63 Manx 500s used a 1-3/8"GP2 Amal. The earlier 500 short-strokes started with only 1-9/16" GP and got bigger with new models. Some tuners fitted 1-1/2"GP carburettorss but unless you do all the modifications to let the engine run to 8000 RPM the gain is small. If you run the standard weight piston past 7200 RPM it will crack soon after.
 
Mark Burgmann
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Hi Ken 1 9/16 should this have been 1 5/16 for the short strokes? Best Regards Mark
 
Ken McIntosh
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Manx Norton Carburettors for 86mm bore 500cc models, from the original Amal listings. 1954-56 500cc Manx uses 1-9/16" T5GP Amal 1956-60 500cc Manx uses 1-5/16" T5GP Amal 1961-63 500cc Manx uses 1-3/8" T5GP2 Amal
 
Mark Burgmann
(read 365643 times)
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Hi Ken The short stroke 30M 1955-1956 T5GP 1 9/32" not 1 9/16"? 1956-1961 1 5/16" going by my Amal list no. 601/3 issue No. 3. Best Regards Mark
 

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