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Old 22-07-2012, 07:49 AM   #24
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Join Date: Jul 2011
Location: Bali Indonesia
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Default HCS installation on a Yamaha scooter.

HCS installation on a Yamaha Mio.

This is an HCS installation that I made on a friend’s Yamaha Mio which is a 125cc 4-stroke step-through automatic.

As I had no idea whether a suitable venturi vacuum could be located; I went for the easy option which is the PCV pressure operated HCS.
I found the PCV outlet (A) easily as it was conveniently located on the front of the engine and was identifiable as the connecting pipe ran directly to the air filter.
I disconnected this pipe at the engine and fitted one end of a piece of petrol pipe to the PCV outlet.
The other end of this pipe was to go to the petrol tank which I intended to double as a bubbler tank.

I wound a length of copper pipe (D) around the exhaust pipe at its hottest point in readiness for connection to the rest of the system.

The black petrol pipe (C) is carrying fuel vapour from the petrol/bubbler tank and the dark grey pipe (B) is carrying the resulting Hydrogen and Carbon gases to the air filter.
Fortuitously; I could utilize the old PCV pipe that I disconnected from the PCV outlet as it was already connected to the air filter.

Up at the petrol tank; I decided to fit the ‘PCV in’ and ‘Fuel Vapour out’ pipes to the fuel level float unit.
Some people use the fuel cap but this is less convenient for the user when refilling the petrol/bubbler tank.

This was an easy job and I just drilled two small holes through the plastic face plate of exactly the same size as the copper pipes to be inserted which fitted very snugly indeed and formed a seal against petrol leakage.
To be absolutely sure; I added a spot of glue once the installation was complete.

The grey pipe (E) is carrying the PCV gases and branches via the ‘T’ connector to the PCV relief screw valve (F) and to the ‘PCV in’ copper pipe (G) which extends down into the tank to well below the surface of the fuel.
The copper pipe (H) is short and takes the resulting fuel vapour to the copper heat tube (D) and the cracked Hydrogen and Carbon on to the air filter via the (B) tube in the previous photo.

The entire installation took me about an hour and used materials that I bought at local stores for a total of just $4.00

My friend drove this motorcycle from Java the day before and used 8.5 liters of fuel.

After fitting HCS; he drove the return journey (taking the same route) and used only 4.5 liters of fuel.

He reported a smooth, quiet ride with sharply increased power and torque.


Last edited by edostar; 22-07-2012 at 11:13 AM.
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