On Dec 17, 2:39*pm, E Z Peaces wrote:
Jay Chan wrote:

There is an "Idle Mixing Needle" and the channel for it. *And I have
cleaned it and used compressed air to blow the channel. *Honestly, I
don't know if this matters or not because the problem that I have is
with running the engine in high speed; therefore, the idle mixing
needle should be irrelevant.

There's an idle mixing needle! *Great! *That should help troubleshooting.

When carburetor people talk about idle and high speed, they're really
talking about throttle opening. *You say the throttle is pretty well
closed, so the idle mixing needle should be the most important adjustment..

1. *Does turning the needle affect engine speed? *If not, it sounds as
if a channel is clogged.

2. *Can you turn the high-speed needle to where the manual suggests,
then adjust the idle mixing needle to run the engine with no choke? *If
you can, and that adjustment is reasonably close to what the manual
suggests, great! *No air leak!







4. * What is the problem of running this snow thrower as is? *I mean
running it in full open choke, with the speed lever at high speed, but
the throttle valve is somehow closed. *Does this mean that the snow
thrower will run slow and cannot throw the snow to the proper
distance? *Sorry, I don't have any snow on the ground to test this.
If it's an air leak, the engine may run rich when the throttle stays
open to throw snow. *With the throttle open, the air leak would matter
less and the rich adjustment of the mixing needle would matter more.

If there is an air leak and the throttle stays open under load, the
engine should be running lean because of the extra air. *This may
explain the reason why the "engine-stall" problem goes away when I
open up the high speed mixing needle an additional 1/2 turn to add
extra fuel to the carburetor. *Is this what you are trying to tell me?

Suppose the throttle is closed and the leak adds 10% to the air the
engine gets. *That will make the mixture leaner. *If you open the
throttle to let 10 times more air through the carburetor and the leak
stays the same, it will be adding only 1% to the air the engine gets, so
it won't matter much.- Hide quoted text -

- Show quoted text -

As mentioned in another of my post, I find that the engine cannot idle
slow. According to other web sites, this means there is likely an air
leak somewhere in the engine. Seem like you are right.

The hard part is to find out where the air leak is. And I will need
to connect an air regulator to my small air compressor and inject 3-
lbs-per-sq-in air through the choke air intake and spray soapy water
around the engine to see where the bubbles will come out.

Meanwhile, I will have to start using the snow thrower today and
tomorrow regardless the fact that the engine cannot idle snow. I
think it should not hurt the engine -- just burn more gas.

Jay Chan