Nirvana TOP 80, Assembly And Maintenance Manual

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last update 23.10.2012
Behind cover B is located the fuel metering mechanism – the fuel spring,
THIS IS THE ENGINES MAIN FUEL CONTROL MECHANISM. When the cover is
removed you will see the lever (E) beneath which is located the fuel spring.
The ideal length of this spring is between 14-15 mm. This length can be
obtained by gently squeezing the spring between your fingers. A new
miracle spring is now available giving better mid range fuel delivery.
This fuel spring length should give you a “Pop Off Pressure” of 0.9/1 Bar. As
an indication of the importance of this calibration – a specific tool is
available (you see photograph under) for measuring the point at which the
pop off pressure is achieved. The tool is available from the distributor shop.
The height of the lever upon which the spring acts, is also critical and should
be 0.5 -0.7 mm above the body of the carburettor.
The adjustment of the fuel lever and fuel spring is a very delicate operation,
involving fragile components and should only be undertaken by an expert.
The carburettors fuel filter is also located here, and can become blocked
with “rubbish” causing a loss of power which is especially prevalent at high
rpm’s.
! Pay attention please
The diaphragm carburettor „pumps“ thanks to the variable pressure inside
the crank case.
The pressure comes to carburettor throught a small hole on the reed valves,
we suggest you to control and clean that hole and the nearest gaskets.
You can use a 2,5 mm drill bit, clean the back side of the hole.
The typical symptom of this defect is an engine that „hauls“ in the final part
of the throttle control (means that the carburettor is unable to pump enough
fuel at high rpm)