Weather Station Information
You must first try and establish optimum carburettor settings in the usual way,
i.e. reading plug, examining piston crown for burn profile, colour etc. and also the
underside of piston crown for colour and density of varnish deposits.
Having satisfied yourself that you have the correct needle, needle clip position,
and main jet take the three readings of temperature, air pressure and
humidity from your weather station.
This then becomes your base line setting according to weather conditions.
Thereafter, it should only be necessary to alter the main jet size according to
what the weather station is telling you.
It may sound complicated but after a few readings have been logged you begin
to form a clearer picture of how the weather affects your carburation and also
how sensitive these machines are to carburettor fine tune adjustments.
Example only (Do not use these settings)
Base Line Settings. Needle 1270. Clip Position 3. Main Jet 180.
Air Pressure 1005 MB. Humidity 60%. Temperature 15 Degrees Centigrade.
The changes affect your setting as follows.
Air pressure +20 MB = Plus 1 Rank on Main Jet.
Temperature +4 Degrees Centigrade = Minus 1 Rank on Main Jet.
Humidity + 20% = Minus 1 Rank on Main Jet.
So it follows, High Air Pressure go richer, High Temperature go weaker,
High Humidity go weaker and vice versa.
Therefore, going on the above example if the readings are
Air Pressure 985, -1 Main Jet
Humidity 40% +1
Temperature 23 Degrees Centigrade -2
Overall –2 on Main Jet = 175.
I hope that makes sense. Any questions please ring.
