DERF
Member
To all of you with the jet rib problem. I got this email today from AVON UK hope it solves some of the problems: The chap did acknowlege the problem, but said (not surprisingly) its not their fault, coz these are Yahama components! Hope it helps!
Avon 320 Deluxe Jet and 400 Deluxe Jet
Service procedure for problems encountered with throttle/gear control operation. –Changing Gear from Reverse to Forwards.
NOTE: This problem is characterized by the fact that it is difficult to remove the throttle/gear control from a reverse position to neutral or forwards while the engine is running. By stopping the engine it is possible to remove the gear from reverse.
NOTE: If reverse is difficult to engage/disengage while not in the water or the engine is not running then there is either a cable fault or the cable position needs to be adjusted at the throttle/gear control end.
This fault is generally caused by the pressure of the water flow from the jet unit locking the reverse gate of the jet unit into the reverse position. This can be rectified using the following procedures. Each of these can be utilized in turn until a solution to the problem is reached.
1. Engine Idling/Tick over speed.
Following the engine break in period it is usual for the idling/tick over speed of the engine to increase slightly causing an increase in pressure on the reverse gate of the jet unit.
Reduce the tick over speed of the engine to the recommended level and retest the reverse mechanism:
· Place the Jet boat in the water, start the engine and warm it up for one or two minutes.
· By turning the throttle stop screw by hand, adjust the engine speed to the specified r.p.m. Turning the throttle stop screw clockwise increases the engine speed and turning it counter-clockwise decreases the engine speed.
· Idle Speed: 1,200 - 1,300 r.p.m.
1. Throttle stop screw.
2. Greasing Points/Adjustment
During use the reverse gate mechanism bushes can become seized and/or worn.
1. Guide pin and bush.
Remove the guide pins and bushes and check for any damage. Replace any worn parts. Replace the bushes and pins and liberally grease all moving parts of the reverse gate mechanism using ‘Yamaha Grease A’ or ‘Yamaha Marine Grease’.
NOTE: The guide bushes should be free to rotate while operating the mechanism.
Adjust the reverse gate so that the guide pins slide to 4mm from the end of the ‘S’ shaped slot in the guide bracket. This position is the second mark which is stamped on the bracket next to the slot.
· Place the throttle lever in the "Reverse" position, so that the reverse gate of the jet pump is down to its stop position. Turn the steering wheel fully to the port (left) side.
· At this position, the clearance between the pin and the pin slot end of the shift rod lever should be 4 mm (0.16 in). If not, adjust it by turning the connector on the back of the control cable. To release the connector from the cable push back the outer sleeve of the connector and lift the cable end upwards to release. Release the lock nut from behind the connector, the connector should then be free to thread either clockwise on to the cable to lift the reverse gate or anti clockwise to lower the reverse gate.
· Retighten the lock nut against the back of the connector, grease the inside of the connector and then reconnect the cable to the reverse gate bracket.
2. Pin.3. Shift rod lever.
· Relaunch the boat and retest the reverse gate mechanism.
4. Bracket Modification
If the problem still exists remove the reverse gate bracket and check it for any damage. The bracket should not show any signs of twisting or bending removed when removed from the jet unit. If twisted or bent in any way this must be repaired or replaced. It is vital that the mechanism operates freely without excessive friction on the jet unit castings.
It is also possible to slightly modify the profile of the ‘S’ shaped slot to allow the smooth operation of the mechanism.
· Remove the bracket by removing the bolts and springs shown and reprofile and deburr the corner of the ‘S; slot as shown.
1. Main pivot bolt and collar2. Side plate fixing bolt and collar3. Pin bolt and collar4. Spring
Reprofile and deburr the corner of the ‘S; slot as shown.
WARNING THE MODIFICATION OF THE BRACKET SHOULD ONLY BE USED AS A FINAL ADJUSTMENT ONLY IF REQUIRED.
WARNING DO NOT REMOVE MORE MATERIAL FROM THE BRACKET THAN SPECIFIED. IF THE CORNER OF THE SLOT IS REMOVED TO A LARGER RADIUS THAN THAT SPECIFIED THE REVERSE GATE WILL NOT LOCK DOWN WHEN IN REVERSE. THE POSSIBLITY THEN EXISTS FOR THE REVERSE GATE TO BE FORCED AWAY GIVING FULL FORWARD THRUST WITH THE CONTROL LEVER IN THE REVERSE POSITION.
· Replace the bracket to the jet unit and reconnect the control cable. Grease all moving parts of the mechanism.
· Relaunch the boat and test the reverse operation.
NOTE: Regular maintenance and greasing of the reverse mechanism is required following any adjustments to keep the reverse operating correctly.
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Avon 320 Deluxe Jet and 400 Deluxe Jet
Service procedure for problems encountered with throttle/gear control operation. –Changing Gear from Reverse to Forwards.
NOTE: This problem is characterized by the fact that it is difficult to remove the throttle/gear control from a reverse position to neutral or forwards while the engine is running. By stopping the engine it is possible to remove the gear from reverse.
NOTE: If reverse is difficult to engage/disengage while not in the water or the engine is not running then there is either a cable fault or the cable position needs to be adjusted at the throttle/gear control end.
This fault is generally caused by the pressure of the water flow from the jet unit locking the reverse gate of the jet unit into the reverse position. This can be rectified using the following procedures. Each of these can be utilized in turn until a solution to the problem is reached.
1. Engine Idling/Tick over speed.
Following the engine break in period it is usual for the idling/tick over speed of the engine to increase slightly causing an increase in pressure on the reverse gate of the jet unit.
Reduce the tick over speed of the engine to the recommended level and retest the reverse mechanism:
· Place the Jet boat in the water, start the engine and warm it up for one or two minutes.
· By turning the throttle stop screw by hand, adjust the engine speed to the specified r.p.m. Turning the throttle stop screw clockwise increases the engine speed and turning it counter-clockwise decreases the engine speed.
· Idle Speed: 1,200 - 1,300 r.p.m.
1. Throttle stop screw.
2. Greasing Points/Adjustment
During use the reverse gate mechanism bushes can become seized and/or worn.
1. Guide pin and bush.
Remove the guide pins and bushes and check for any damage. Replace any worn parts. Replace the bushes and pins and liberally grease all moving parts of the reverse gate mechanism using ‘Yamaha Grease A’ or ‘Yamaha Marine Grease’.
NOTE: The guide bushes should be free to rotate while operating the mechanism.
Adjust the reverse gate so that the guide pins slide to 4mm from the end of the ‘S’ shaped slot in the guide bracket. This position is the second mark which is stamped on the bracket next to the slot.
· Place the throttle lever in the "Reverse" position, so that the reverse gate of the jet pump is down to its stop position. Turn the steering wheel fully to the port (left) side.
· At this position, the clearance between the pin and the pin slot end of the shift rod lever should be 4 mm (0.16 in). If not, adjust it by turning the connector on the back of the control cable. To release the connector from the cable push back the outer sleeve of the connector and lift the cable end upwards to release. Release the lock nut from behind the connector, the connector should then be free to thread either clockwise on to the cable to lift the reverse gate or anti clockwise to lower the reverse gate.
· Retighten the lock nut against the back of the connector, grease the inside of the connector and then reconnect the cable to the reverse gate bracket.
2. Pin.3. Shift rod lever.
· Relaunch the boat and retest the reverse gate mechanism.
4. Bracket Modification
If the problem still exists remove the reverse gate bracket and check it for any damage. The bracket should not show any signs of twisting or bending removed when removed from the jet unit. If twisted or bent in any way this must be repaired or replaced. It is vital that the mechanism operates freely without excessive friction on the jet unit castings.
It is also possible to slightly modify the profile of the ‘S’ shaped slot to allow the smooth operation of the mechanism.
· Remove the bracket by removing the bolts and springs shown and reprofile and deburr the corner of the ‘S; slot as shown.
1. Main pivot bolt and collar2. Side plate fixing bolt and collar3. Pin bolt and collar4. Spring
Reprofile and deburr the corner of the ‘S; slot as shown.
WARNING THE MODIFICATION OF THE BRACKET SHOULD ONLY BE USED AS A FINAL ADJUSTMENT ONLY IF REQUIRED.
WARNING DO NOT REMOVE MORE MATERIAL FROM THE BRACKET THAN SPECIFIED. IF THE CORNER OF THE SLOT IS REMOVED TO A LARGER RADIUS THAN THAT SPECIFIED THE REVERSE GATE WILL NOT LOCK DOWN WHEN IN REVERSE. THE POSSIBLITY THEN EXISTS FOR THE REVERSE GATE TO BE FORCED AWAY GIVING FULL FORWARD THRUST WITH THE CONTROL LEVER IN THE REVERSE POSITION.
· Replace the bracket to the jet unit and reconnect the control cable. Grease all moving parts of the mechanism.
· Relaunch the boat and test the reverse operation.
NOTE: Regular maintenance and greasing of the reverse mechanism is required following any adjustments to keep the reverse operating correctly.
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