The timing gear and cams fitted to Laser engines are extremely robust and
unlikely to give any problems. The backplate should not be taken apart unless
absolutely necessary.
There are no markings on the cams or pinion
drive fitted to Laser engines. With the
single cylinder engines the cam
followers will hold the cams in position if back plate is removed provided the
cylinder head has not been removed.
The cams fitted to twin cylinder engines will
generally come out if the backplate is removed.
LASER
SINGLE CYLINDER ENGINES
Laser-61, 75, 80, 90,100, 120, and 150.
The two cams are identical and
interchangeable.
The inlet starts opening at approximately 400 before top dead centre. (BTDC)
The exhaust finally closes at approximately 300 after top dead centre. (ATDC)
Laser-45, 50, 62, and 70.
The inlet cam has a sharper profile (it is
more pointed) than the exhaust.
The inlet cam starts opening at approx. 300
BTDC.
The exhaust cam finally closes at approx. 300
ATDC.
Picture
shows cams on Laser-80 at top dead centre
Laser-180
The timing is symmetrical. Inlet starts
opening at approx 350 BTDC
Exhaust closes 350 ATDC
LASER TWIN
CYLINDER ENGINES
150v, 180v, 200v, 240v 300v
There are three cams fitted to Laser twin cylinder engines. The inlet cam
is a twin cam. (top centre in the picture). Fit this to start opening the inlet
approximately 400 BTDC on the right hand cylinder first. Next fit
the exhaust valve for the right hand cylinder to close approx 300
ATDC.
Rotate the crankshaft so the left hand cylinder inlet valve starts
opening. Next fit the exhaust valve to finally close at approximately 300
ATDC.
Picture shows Vee twin cams
with left hand cylinder at top dead centre. Note position of exhaust cam.
To find top dead centre. A
piece of wooden dowel or plastic can be inserted vertically through the glow
plug hole to touch the piston. Rotating the crankshaft will push the dowel. Top
dead centre will be at the highest point. Make a mark on the propeller driver
and front housing to show this point.
Before running the engine turn the crankshaft over carefully. If the timing is not correct the valves may collide with the piston.
The timing can be reset at
our factory. There will be a charge of £20.00 plus return postage for the
Single cylinder engines plus return postage and £30.00 plus postage for the
Twin cylinder engines.