| One reason some engines run rough can be due to the diaphagm
tap not working properly, either they have been incorrectly fitted or punctured.
Othe reasons are the tap can be blocked by debri in the petrol (gas) tank
and loose fitted/missing vacuum pipe. Leaking fuel from the tap is usualy
a sign that the diaphragm has been damaged, or incorrectly fitted.
How the duaphragm tap works:
The air/fuel mixture is sucked into the combustion chamber, the
small tube which you will usualy find on the inlet connection the barrel
and the carburetta on pot No.1, the other end runs to the pertrol (gas)
tap. also sucks air from the tube which, inturn, pulls the rubber diaphragm
in the tap, opening the tap and allowing fuel into the carb(s)
If you want to know what the "prime" setting is for, and when to use
the prime setting:
Use prime when the machine has not ben run for a few days/weeks
where fuel has evaported from the carbs.
Use Prime if you have to drain fuel from the float bowls. It lets the
carb(s) fill faster lesseinng strain on the starter motor and means your
battery will cope easier.
If you run your machine when prime: You will probably use more
fual than normal, worse case, are more chance of fuel leaks, especialy
when you park your machine
||On this type of pet cock the options are: "Reserve" (the shorter of
the tubes which goes into the tank), "On" (the longer of the tubes which
goes into the tank), & "Prime"(which opens the diaphragm and lets the
pet cock work as a gravity fed tap). On some machines there is no prime
which is replaced with an "Off" switch, stopping any fuel from leaving
When "On" or "Reserve" the diaphragm is supposed to stop the
fuel leaving the tank
|On the back of the tap you will see four small crosshead screws, by
removing these lets you check the diaphragm.
||It's a good idea to hold the casing in position while doing this as
there is usualy a spring underneath the case which can get lost too easily.
|The Diaphagm it's self comprises of two rubber flaps over a central
piller with a o seal and a plate, if there any splits in the rubbers, or
any signs of perishing, replace the diaphragm, which are not too expensive.
On the left you can see the filter which is usualy inide the petrol
tank, the smaller of the brass pipe connections is the diaphragm tube fits.
A stripped Diaphragm tap
Note: The photo's shown here are from A Kawasaki GPZ RX1000, there are
differnces in Honda and Suzuki pet cocks, but the basics are the same.
Just remember which part come where when dismantling other pet cocks.