How to Vent an SV650 CA Emissions Gas Cap

Patrick Mullen pmullen.lists at
Mon Jul 16 11:08:02 PDT 2007

I put a CA cap on a 49-State tank with the expected venting issues.
Finally, I fixed the problem yesterday and did a quick write-up since
I couldn't find one specific to the SV.

The contents below, including pictures, are located at:

Venting a California emissions SV650 cap is really simple.  They have
a rubber cone stopper plugging the channel that lets air through the
channel to the external vent.  The kicker is the more vacuum present,
the tighter the seal.

1) Use the key to open the gas cap as if you were filling gas.  Remove
the four bolts holding the outer ring to the tank (the other four are
merely for display).

2) Flip the cap over, so the keyhole is facing downward against your
work surface.  Important -- Do not lift the gas cap off of the table,
or at a minimum make sure the flap that covers the keyhole does not
open up.  If you do, a tiny spring with an even tinier ball bearing
that is used as a retainer will fly off somewhere, never to be seen

3) Remove the screws holding the key assembly to the underside of the
cap.  All of the screws are the same, so there's not really much need
to keep track of where each one goes.  You do *not* remove the screw
to the lower left that holds the metal plate in place for the key flap
retainer spring.  See warning for step #2.  :)

4) Lift the key assembly off of the cap and flip it over.  You should
now be looking at Figure 1.  Notice that on my gasket you can see
where the vacuum has sucked the gasket downward to the point where a
small gap forms next to the key mechanism, causing the
whistling/sucking sound when riding or parked in the sun.  This is the
problem we're fixing here -- that of an improperly vented gas tank.

5) Remove the gasket.  Now you should be looking at something like
Figure 2.  The pencil is pointing at the plug that I believe is added
to California Emissions gas caps.

6) Lift the plastic mechanism pointed to by the pencil out of the cap.
 It's not fastened by anything and should be easy to lift.
Technically it shouldn't need to be removed to accomplish the next
step if you have problems removing it.

7) Pull out the plug. See Figure 3.

8) Reassemble in reverse order.  It makes the most sense to put the
gasket on the cap with the two pins sticking into their respective
holes, line up the key mechanism, and put the screws back in.  Then
put the cap back on the bike.

9) You're done!  Note that the way Suzuki tells the difference between
CA and regular caps is by a "marker bolt" on the ring. If you have
tried to put a CA cap on a 49-State tank or vice-versa, you need to
swap the marker bolt, which is slightly longer than the other
"cosmetic" bolts so that it'll fit.

Hope this helps!

2003 Triumph Sprint ST
2004 (race) / 2001 (street) Suzuki SV650
2000 Yamaha WR-400
1975 Harley FXE1200

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