On Dec 16, 6:12*pm, E Z Peaces wrote:
Jay Chan wrote:

My questions a

1. * Where does the engine get air when it is under load and the
throttle valve is somehow closed? *Is there a big air leak somewhere?

If there's no snow, I guess you aren't running it under a load. *It
shouldn't take much throttle to run the engine pretty fast without a
load. *If there's an air leak, it would take even less throttle opening..


Thanks for the reply.

I try running the snow thrower under load by the combination of using
the self-propel function of the snow throw to run it in high speed,
and using the snow throwing mechanism at the same time. But the
throttle valve is still closed when I run it under load. There is a V-
belt connecting the engine to the snow throwing mechanism. If I turn
off the snow throwing mechanism, the V-belt will dis-engage the engine
from the snow throwing mechanism, and put the engine off the load. On
the other hand, if I turn ON the snow throwing mechanism, the V-belt
will engage the engine with the snow throwing mechanism, and I believe
this puts the engine under load.


2. * Where is the likely air leak? *There is no gasket between the
engine air intake and the carburetor. *I don't see a gasket there, and
the Technical Manual doesn't show there is a gasket either. *May be I
should try adding some gasket in a tube kind of thing? *Other than
this, where else is the likely air leak? *Does this mean that I need
to fully disassemble the whole engine block?

I can't remember if air can be sucked in past a cylinder-head gasket.
Why not take a syringe and squirt water around the carburetor and
cylinder head? *If you can affect the engine speed that way, you've
found an air leak.


Test didn't reveal where the air leak is. I tested this by using both
a feather and the water test. I tested this around the engine,
especially in the joint of the carburetor and the engine cylinder.
The feather didn't show any air movement when the engine was running
-- except near the fly wheel where I believe the cooling fan is.. And
the water test didn't slow the engine in anyway. Therefore, I don't
know where the air leak is.


3. * The fact is that I can keep the choke at full open after I have
adjusted the mixing needle. *Does this mean that I have no problem
getting fuel from the mixing needle? *Does this also mean that dirty
carburetor is not an issue here?

There could be a passage to add a little gas at low throttle settings.
That part could be clogged. *(I don't know if your carburetor has such a
passage.)


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.


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?

By the way, can you show me a link to the tachometer that you use to
connect to the spark plug? *May be I am not using the correct key
words to search for it because I cannot find it in the net.

I may have found something better, a vibra tach. *You put it against the
engine and adjust it so the reed vibrates the most.

I think I have found what it is called. It is called "Hour Timer" and
is connected to a spark plug to count the number of sparks. I have
decided to get an optical tachnmeter instead. The reason is that it
is cheap, and I have found a way to get access to the spinning part of
the engine.

Seem like I cannot determine where the air leak is, and I am not sure
if the engine really has an air leak or not. Therefore, I need to get
a tachometer to see if the engine can run in high speed or not. If
the engine can run in high speed, this may mean I really don't have a
problem, and I may just have to accept the fact that the throttle
valve cannot open wide. If the tachometer shows that the engine
cannot run in high speed when it is supposed to be, this means I
really have a problem, and I will try to manually open the throttle
valve slowly to see if doing this can make the engine run in the
correct high speed (3600 rpm). If the engine can run in the proper
high speed when I manually open the throttle valve, this may mean that
the spring that is supposed to keep the throttle valve open has become
too weak, and the suction from the engine is too powerful for the weak
spring and sucks the throttle valve closed. That's despite the fact
that the spring "seemed" strong when I manually moved it around.

Because I need to manually open the throttle valve, I am afraid that I
may run the engine too fast. Therefore, I definitely need to get a
tachometer before I do anything further.

Jay Chan