Honda PA50 - Jet Size 75? - Advice drilling out carb to 12.7mm


My Camino has a stock Keihn carb with no mods.

I want to enlarge carb to 12.7mm by drilling it out has a 1/2inch drill bit

Just taken off float bowl to check jet size as was just curious.

Looks like a stock Keihn main jet at size 75?

Bit difficult to see as the 5 has been chopped off.

Would everyone confirm that this is a size 75 main jet?

If I were get go up in size say 80 that would be a larger diameter hole and visa versa?

Reading up on here I don’t think this is what normally comes on the carb?


The PA50II carb has a 12mm venturi, versus a 10mm venturi of the PA50I version. It also has a #78 jet versus a #60. [A PA50II carb, reed block, and manifold on a PA50I engine will net you 5+MPH]

Any advice would be appreciated.



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