HDManny wrote:
>Thanks for the reply Albrecht.
>After re-examination of all the components I realized the boot that
>goes over the throttle cable at the carb was not attached. I guess it
>was sucking air. It is re-installed and working almost flawlessly.
Sudco International buys Mikuni and Keihin carbs and makes up custom kits for
various applications. They will probably have parts for a Keihin PD carb.
http://www.sudco.com/
The PE20 & 36 hyperlink shows a starting enrichener that is operated by a
lever that pivots on the end, lifting the air valve when it's pulled up.
This drawing shows that the carb uses hexagonal shaped jets which are known
as "hex" jets. If you had a #100 hex jet and you wanted to go 10% richer on
the
main mixture, you would install a #110 hex jet.
Round jets what are installed with a screwdriver instead of a wrench don't
work that way. If you went from a #100 main jet to a #110 main jet, the hole
in the jet would have about 20% more area and it would flow 20% more fuel.
> My
>son says at full throttle it "bogs" a bit. I imagine that is a minor
>adjustment I'm not sure how to do yet.
Well, you will just have to study the problem by listening to the motor and
reading the spark plugs.
If the engine sounds like it's gargling on gasoline when it bogs at high RPM
and you look at the spark plug and it's all covered with dry black soot, you
know the main jet is too large (or that it has fallen out and is laying in
the float bowl).
OTOH if the main jet is too small, you might see little black specks that
look like grains of pepper on the nose of the spark plug. This indicates the
mixture is so lean it's pre-igniting, and if you let that continue, the top
of the piston will start melting and you will see little balls of aluminum on
the spark plug.
I wish I could describe the groaning sound an engine makes when it's running
too lean and overheats before it melts the piston top.
The old standard for judging mixture richness used to be a light tan lead
deposit on the spark plug, but that doesn't work with unleaded gas.
Nowadays, tuners expect to see a narrow ring of black soot deep inside the
spark plug when they look at it with their magnifying flashlight.
--
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http://www.motorcyclekb.com/Uwe/Forums.aspx/yamaha/200708/1 >> Stay informed about: Takegawa TTR90 90cc to 110cc Kit Kehin PD Carb Issue 
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