Please follow these instructions carefully

With a sharp instrument mark the front of the cooling fins and cylinder unit so that these two components can be replaced exactly as found.

Now remove the holding-down screws, and the cooling fins. 249/19 DS and earlier models only:- Cut off lowest 2 fins and file small flat to clear silencer box on next fin if necessary. 149 DS and earlier, remove ONE FIN ONLY. 049/06 no fins need to be removed.

Place the first sealing ring over the cylinder unit on to the case: follow this by the silencer, trying to get the screw holes in the correct position for assembly. The top sealing ring is now placed on the silencer ring, and is followed by the cooling fins.

Holding the engine in your left hand, with your left thumb on top of the cooling fins, take a needle and probe down the screw holes to make a SMALL HOLE in both sealing rings in each of the three screw holes. DO NOT make this a large hole, or you will lose gas (and noise) past the screws.

IT IS IMPORTANT that the sealing washers are trapped and held in their correct position when the holes are pierced.

You can now screw in the holding-down screws using a sharp screwdriver, and taking the greatest care to note that the cylinder unit is still correctly positioned, and trapped, as it was when the engine was dismantled.

If you feel that you have reason to believe that your cylinder unit is not correctly held, please send the engine and the complete silencer set direct to:-

PROGRESS AERO WORKS, Union Street, Macclesfield with a fitting charge of £18 when the silencer will be correctly fitted to your engine and returned with despatch.

Your PAW engine is fitted with the new VARIJET carburetter to give perfect control over the whole speed range.

To set the carburetter, open throttle fully and screw needle in as far as it will go without force. Unscrew around 3 1/2 full turns. Start the engine normally as described in the instruction leaflet. This may be done at a reduced throttle opening if desired. Warm the engine at 1/4 to 1.2 throttle for 30 seconds, then set needle and compression for full power at full throttle (Instructions). Check tick-over - R/C setting, test Trim Stop. Initial needle settings can vary with different fuels. Safe slow speed is around 1000 to 1500 r.p.m. Too slow setting can overcooling in prolonged idle, which will affect pick-up. Steady throttle movement is best - around 2 seconds closed - open.

Cleaning, Dismantling And Assembly.

Remove lever and nut, needle and its nut and carrier and 2mm Allen cap screw. Withdraw barrel and spring if fitted, unscrew jet from barrel. Clean all parts in suitable solvent, dry with lint free rag. Special care with jet and jet efflux holes is required. Assembly. Screw needle carrier 3-4 turns into steel sleeve and secure with small nut. Screw jet into barrel to position efflux holes centrally in throat, across the airflow. Insert spring and barrel into sleeve and secure with cap screw taking care to engage slot before tightening. Fit and lightly tighten throttle level nut. Close throttle fully, screw in needle closed without force to lock all together. Finally position level (closed position) as required and fully tighten large nut. Loosen needle 2 turns, check position on the efflux holes which must not be visible looking into intake at full throttle. Set needle to 31/2 turns open as before and re-fit throttle to engine.

  1. Check the gap between the fins & the crankcase is the same as the muffler ring or no smaller than -.005 inch.
  2. If the gap is smaller than the ring, skim the bottom of the fins or rub on abrasive paper until the gap is the correct fit. If the gap is too large, skim or use abrasive paper to the top of the cylinder until the fit is correct.
  3. If the gap is slightly too large this is preferable to a gap that is too small. If the gap is too small, the cooling fins will not hold the liner in place and it will move during use which may cause damage to the engine.
  4. Clean all parts and oil before re assembly.

Progress Aero Works accept no liability for commercial loss or damage, accident, injury or fatality arising from the use of PAW products.
It is the responsibility of the user to use PAW products in a properly safe manner.

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