Vire 7 - Adjustments

Adjusting the Carburettor

Idling Speed (Idling Jet / Idling Mixture & Throttle Stop Screw / Idling Speed Screw)

  1. Clean the spark plug and check the spark plug gap.
  2. Unscrew the idle mixture screw 1¼ to 1½ turns. (The original Operator's Manual recommends 1¼ turns. The newer version advises 1½ turns.) A screwdriver is needed for this adjustment.
  3. Start the engine and run until warm.
  4. With the gear lever in neutral, close the throttle and adjust the idle speed screw to set the speed to between 1200 and 1300 RPM (At this speed, the engine will tend to 'four-stroke'). Do not let the engine idle at more than 1300 RPM
  5. Put the gear lever into the 'ahead' position. The engine speed should not fall below 1000 RPM
  6. If the engine speed falls below 1000 RPM in 'ahead' at low throttle, adjust the idle speed screw until the engine is running at 1000 RPM

Full Power (Main Jet / High Speed Mixture Screw)

Preliminary Setting of Main Jet

Open the high speed mixture screw 1¼ turns. (This is done by hand, without the need for a screwdriver.)

Final Setting of Main Jet

This must be carried out when the boat is underway. According to the Manual, depending on the type and size of boat, the high speed mixture screw may need to be adjusted either way to obtain maximum speed. Advice from Crinan Marine and the Webmaster's personal experience* suggest that the optimum setting usually lies between ¾ and 1 turn.

* Webmaster's Comment: My Vire 7 powered a Leisure 22, a bilge keeled sailing vessel with a design displacement of 1450 kg.

Adjustment of the Magneto Breaker Points Gap

The magneto contact breaker points gap in a new engine is adjusted at the Factory to its proper value. After 300 running hours it may be necessary to check the gap and possibly readjust it. The following procedure should be adopted:

  1. Remove the starter pulley.
  2. Rotate the crankshaft until the breaker point gap is at maximum.
  3. The breaker point gap should be set to 0.45 mm (0.016 inches) by means of a feeler gauge.
  4. If necessary, adjust the gap by loosening screw #1 and turning point #2 from notch A.
  5. Retighten screw #1.

Timing Adjustment

The timing is adjusted at the factory to its proper value to give the greatest efficiency and starting characteristics.

If the magneto statorplate has been removed it must be fitted so that the fixing screws pass centrally through the oval shaped slots. This will ensure the correct timing, provided that the magneto contact breaker points gap is correct.

If rechecking or adjustment of the timing is needed, the following procedure should be adopted:

  1. Check the magneto breaker points gap and adjust it if necessary.
  2. Turn the flywheel clockwise (direction of normal rotation) until the notch on the V-belt pulley indicates the fixing level of the bracket on the left side of the engine (when viewed from the front). The breaker points should just open at this position, which is 30 degrees before top dead centre (BTDC). This corresponds to the position of the piston in the cylinder being 5.8 mm (0.23 inches) BTDC, which can be measured with a depth gauge type timing tool through the spark plug hole.
  3. If the timing is incorrect, loosen the fixing screws of the stator plate
  4. Retighten the fixing screws on the stator plate.
  5. Recheck the magneto breaker points gap and readjust it if necessary.

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