Randy's Cycle Service Explains Carburetors, Choke & Cold Starting - vintage motorcycles. Randy's Cycle Service & Restoration in central Virginia USA. We service & restore all makes & models. We do not source or stock parts or sell vehicles. Technical advice starting at $25. Randy's Cycle Service & Restoration, www.rcycle.com
How Motorcycle Carburetors work and how to tune and clean them
Here's a link to the kind of carb cleaner I like best (it IS the best)
hey... awesome video..nicely explained !
just one question. Please do tel me wts AIR NEEDLE and LOW JET used for
again. ? i mean how and what do they work?
The air needle is like a transitional restriction to increase vacuum
pressure and tapered to prime the main jet flow gradually to ramp up fuel
flow from the idle/low circuit to the main circuit. Think of the circuits
like gears or stairs. The needle covers transition between 3rd gear to
about 5th gear on a six speed. It overlaps basically. Fuel is getting by
it from the idle/low- on through to where it's completely out of the way of
the main jet and the main jet fuel flow is roaring like the
Without the needle the carb would work, but not as smoothly through middle
throttle (where most people ride and have the most fine input or throttle
roll back and forth.
The low jet is like second gear on a transmission. You can shift from 1st
to 3rd, but again you risk stalling and it won't be as smooth. Also there
isn't really the mechanical inertia to carry the process on like you have
with a rolling vehicle with a flywheel on the engine and the wheels
turning. The pistons still create vacuum every other time they go down,
but air just doesn't have the punch that steel does when in motion.
The circuits in a carburetor have to be there or you would have a limit on
RPM range. An idle jet can't deliver enough fuel to really scream, and the
main jet couldn't go slow and would be VERY hard to start because the
engine would have to be spun up really fast. So you have usually four or
five circuits (I want to say jets, but their physically different) that get
air flow like stairs as the throttle opens. They are typically 1. Starting
circuit (choke on) 2. Idle circuit 3. low jet 4. Jet Needle 5. Main jet.
How Motorcycle Carburetors work and how to tune and clean them Check out
my other channel here http://www.youtube.com/watch?v=1KKvwMaIotA