Favourite Carb!

Tuearts right boot said:
I like a basic Amal carb. Usually found on British Seagulls or 34cc JAP 2 strokes. Simple and reliable. Stripped down and cleaned in about 15 minutes, although the American ones on the Johnson/ Evinrude 3 hp 2 strokes are a bit more intricate, requiring both high and low rev needles to be adjusted to get optimum performance out of the little buggers.
Click to expand...
They have 2 needles?
Didn't know that, how does that work, are they on the same slide, looking after 2 jets simultaneously?
Genuinely interested mate
 
crublue1 said:
They have 2 needles?
Didn't know that, how does that work, are they on the same slide, looking after 2 jets simultaneously?
Genuinely interested mate
Click to expand...
The Amal carbs on a small 2 stroke only have one, a large needle moving in a piston motion in a alloy sleeve but the other American ones have 2. .....The main jet that sets the high speed is situated at the bottom of the float bowl and meters the fuel going in to the carb and subsequently the engine, screwing in or out lets more or less fuel in, you want it lean or there abouts, this should be done first. The slow speed needle is situated above and meters a very small amount of fuel when idling or running slow, this is a bit more forgiving. It's a bit of a patience game when setting them to get the engine to run sweetly, it's great when you get just right and as long as the needles and ports are clean and not damaged it's time well spent.
I bet you're glad you asked !!!!
 
Tuearts right boot said:
I like a basic Amal carb. Usually found on British Seagulls or 34cc JAP 2 strokes. Simple and reliable. Stripped down and cleaned in about 15 minutes, although the American ones on the Johnson/ Evinrude 3 hp 2 strokes are a bit more intricate, requiring both high and low rev needles to be adjusted to get optimum performance out of the little buggers.
Click to expand...
They have 2 needles?
Didn't know that, how does that work, are they on the same slide, looking after 2 jets simultaneously?
Tuearts right boot said:
The Amal carbs on a small 2 stroke only have one, a large needle moving in a piston motion in a alloy sleeve but the other American ones have 2. .....The main jet that sets the high speed is situated at the bottom of the float bowl and meters the fuel going in to the carb and subsequently the engine, screwing in or out lets more or less fuel in, you want it lean or there abouts, this should be done first. The slow speed needle is situated above and meters a very small amount of fuel when idling or running slow, this is a bit more forgiving. It's a bit of a patience game when setting them to get the engine to run sweetly, it's great when you get just right and as long as the needles and ports are clean and not damaged it's time well spent.
I bet you're glad you asked !!!!
Click to expand...
Yes, I'm glad I asked. Thanks for the detailed explanation, I get it now.
I've only ever worked on Japanese carbs with a single needle, the height of which at a given throttle position dictates which jet is active, either slow or high, or both. I think that's why fuel level (float bowl height) is pretty crucial in this sort of
Set up.
I have 3 bikes with multi carbs, they need to be maintained, so I have a bit of experience.
Thanks for the explanation, appreciated
 
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