Suzuki RG500 GAMMA
SUZUKI RG500 GAMMA - SUZUKI RG500 GAMMA - SUZUKI RG500 GAMMA
RG 500 Power Valve Diagnostic and Setup
Symptoms of
Malfunctioning AEC:
I. Symptom: The bike runs
perfectly normal up to 8000rpm, where it flattens out. As revs
increase to redline, power stays flat.
A. Cause: Power
valve stays in open (low rpm) position, and does not close at 7500rpm
II. Symptom: The bike seems OK down low, but stumbles
badly from 5500-7000rpm. All clean by 7500rpm and runs great to
redline.
A. Cause: Power valve stays in closed (high rpm)
position at all times.
III. Symptom: The bike runs
adequately but not sharp below 7500rpm. Mimics a tired plug or
two. Runs great on top.
A. Cause: One or more PVs
are installed 180 degrees out of phase, causing the lip of the valve
opening to protrude into the roof of the exhaust port, creating
turbulence. This stops when the valve closes.
B. Cause:
The positive stop cap on #4 cyl PV is installed upside-down,
causing the valves to come
to rest partially closed when
in the low rpm position.
V. Symptom: The bike has lackluster throttle response, and does not run very well anywhere. Top end is
weak.
A. Cause: PV system is non-functional and has come
to rest in half open position.
AEC Setup
Let's assume
a few things first. The bike's together, in running order, with
the lowers and belly pan removed. So you want to know the
operational status of your Automatic Exhaust Control system,
eh?
Start the motor. From the right side of the bike, operate
the throttle while shining a light under the gas tank onto the Power
Valve servo motor (follow the PV cables up to the servo location) and
observe the cable pulley on the servo. The mark (cast-in line) on
the pulley should be at 0 degrees, or straight up when the revs are
anywhere below 7500rpm. As you bring the revs up past 7500rpm, the
pulley should snap 100 degrees clockwise, closing the valves. When
the revs drop back down below 7500rpm, the pulley should return to 0
degrees promptly. If this is happening as described, then all PV
related electronics are fine. If not, check for any loose
connections with the servo motor or the AEC control unit (gold box
located under the taillight attached to the rear fender). If the
servo pulley moves at all, your connections are fine. If nothing
appears to move, pull up on the PV cable housing #1, located at #4 cyl.
If you feel a tug on the cable housing when taking the revs beyond
7500rpm, then something is binding in the valve area or the cables are
installed wrong. Check to see that each cable is in good condition
and routed correctly; i.e. #s 1-4 on the servo motor matched with #s 1-4
on the PV housings. If you still get no motion
at the cable, check the condition and age of the battery. An old,
worn out battery will inhibit proper PV function. If the battery
is sound, you may need a new servo motor assy. A common
malfunction in the servo concerns a micro volt coil which signals valve
position to the control unit. When these fail, the servo motor
must be replaced. (Note: Testing the servo motor with
DC voltage from the battery will not show the problem. The coil is
very delicate and be damaged by powering it up with any power source.
It is triggered by a magnet connected to the servo drive gear
rotating past the coil, exciting it to send it's signal). The AEC
control unit is very reliable and not prone to failure.
To check
for proper orientation of the power valve in the cylinder, remove the
rear PV end caps and slide the valve out, exposing the slot in the
valve. Look for a raised notch on one wall of the slot in the
valve. The valve should be positioned with the opening at the top
and bottom and the raised notch located to the piston side.
This is the standard open (low rpm) position. Minor carbon
buildup in this area is not a concern since the valve alters exhaust
resonance and not flow. On the front cyls. remove the lower pipes
to access the exhaust port. Insert your finger into the roof of
the port and into the PV slot. The notch can be felt on the piston
side of the valve. If one or both valves are out of phase, they
can be corrected by partially removing the #2 cyl valve and rotating
either one accordingly. Some common causes for sticking PVs
are--
Cyl head bolts (6mm) are too long due to excessive head milling
or the incorrect bolt installed
(stock bolts are 20mm in length) and
are touching the PV.
PV slot has been deformed by placing a
screwdriver or some such in the slot to hold the valve to turn the
pulley bolt, denting the valve out of round.
PV cap
installed without a gasket. Without the gasket in place, the cap
goes in too far and binds the PV.
Keep in mind that if only one of
the PVs is stuck, the whole system jams.
Power Valve Cable
Adjustment
Verify that all cables are routed correctly.
Remove the #s 2&4 PV housing covers and re-install one screw
in each housing. Rotate the PV servo pulley to 0 degrees (straight
up). Adjust each PV cable to align the cast in mark on the pulley
with the notch in the PV housing. Allow for 1mm of play in the
cables and cinch down the lock nuts on the cables. Install the
rear PV cover with the raised stop on the pulley engaging the cover
between the two bumpers. These bumper stops are positioned in the
cap so that there is over 180 degrees of rotational room on one side of
the cap and only 120 degrees available on the other side. Install
the cap where the raised pulley stop engages the cap within the 120
degree area of the cap.
Rotate the PV system by turning the servo
pulley or the front PV pulley. Each location should rotate
100dg
and return to straight up on the servo and mark to notch on the
PV. Install the front cap and go shred!
----------
SUZUKI RG500 GAMMA - SUZUKI RG500 GAMMA - SUZUKI RG500 GAMMA
Rob Koopman
(
Rob.Koopman@inter.NL.net
)
RG500 Index