| The carburetor provides air and fuel to the engine and the spark plug
ignites the fuel/air mixture. It is important to have the right ratio
of Fuel to Air in order to achieve good combustion. How do you tell
if your engine is tuned with the right Fuel/Air ratio? Remove the
spark plugs and have a look.
Tools needed:
Spark Plug Wrench
Stiff bristled brush (non-metallic)
Spark Plug gapping tool
Small slotted type screw driver.
Ordinary Household fan
Remove the boot from the spark plug. look in around the plug and
remove any dirt that is hanging around the base of the plug. We wouldn't
want any of that falling into the cylinder.
Using the Spark Plug Wrench, remove the plug. Look at the bottom
end, the electrode. Inspect it for pitting, cracks or sludge.
If you see any of these, the plug will have to be replaced. If you
see sludge, you may need to have your engine repaired at the shop.
A detailed explanation of spark plug problems can be found in most good
repair manuals.
A lot can be read from the colour of the plug. A whitish, gray
plug tells you that the engine is burning too lean (not enough fuel).
A sooty black plug tells you that you are burning too rich (too much fuel).
The ideal colour for a plug to be is tan/brown. This will tell you
that the fuel air mixture is just about right. For more info, Click
here. Check the gap of the plugs with your Spark Plug Gapping
tool. This is an inexpensive tool that can be found at most any
automotive tool shop. For the Virago 1000, the gap on the plug should
measure 0.028in.
To achieve the right fuel/air mixture tests and adjustments are usually
done by a qualified mechanic with a pressure gauge and a few tools.
I, however, am going to show you how to get good results using only your
ears and a screw driver. First, put the plugs back into your bike.
Using only your fingers, gently screw the plug in. If needed, use
the Spark Plug wrench, with a light touch. Once the plug cannot be
finger turned anymore, tighten it with a wrench 1/4 turn. The whole
point of this is not to strip the threads on your cylinder head.
Place your bike on the center stand and set up the Household fan so
that it blows across the cooling fins of your engine. Start the bike.
Adjust the throttle trim screw until the engine rev's reach 2,000 rpm. |
Warning,
be careful when performing this next step, so as not to burn yourself.
Underneath each carburetor will be found a small hole. Inside this
hole is a pilot adjustment screw. Using the small, slotted type
screwdriver, slowly turn the adjustment screw clockwise until the engine
starts to sputter. Once the sputtering starts, back the screw off
(turn it counterclockwise) until the sputtering stops, then give it an
additional 1/2 turn. Repeat this procedure for the other carburetor.