First remove chain guard. Then take off flywheel and dynamo belt. (see instructions, page 27). Take off sparking plug, exhaust pipes, carburetter, ignition control wire and oil pipe. Remove front engine bolts, take out rear engine bolts, leaving engine plates and dynamo in position. The engine will now come out easily.

To Dismantle Engine. Proceed as described under " Decarbonis­ing." Also remove the ignition timing cam ; to do this take out the hexagon screw holding it, and screw into the cam the large hexagon-headed screw found in the tool kit. Now remove oil pump by taking out cover plate screws.

The only thing left is to take out the crankcase bolts, when the crankcase can be split and the crankshaft assembly removed.

To Take Engine Out of Frame and Dismantle Engine (Three-speed). First remove chain guard. Then take off flywheel and dynamo belt. (see instructions below). Take off sparking plug, exhaust pipe, carburetter, ignition control wire, and oil pipe. Now remove remaining part of chain guard. Remove front engine plates, take out rear engine bolts, leaving engine plates and dynamo in position. The engine will now come out easily.

To Dismantle Engine. Proceed as described under " Decarbonis­ing." Also remove the ignition timing cam. To do this take out the hexagon screw holding it, and screw into the cam the large hexagon headed screw found in the tool kit. This will draw off the cam. Should this screw be lost, use an engine bolt. Now remove oil pump by taking out cover plate screws.

The only thing left is to take out the crankcase bolts, when the crankcase can be split and the crankshaft assembly removed.

Removing the Flywheel (Three-speed). Hold the rim of this whilst the flywheel locking nut is unscrewed. The nut will be tight at first, then it will go round easily until it again locks and starts to draw the flywheel off. The nut will require considerable force to start the wheel off its shaft and it will then come easily. The special spanner provided should be used and a hammer is generally necessary to help turn the spanner.

Should the wheel prove obstinate, a sharp blow with a hammer on the end of the nut in addition to the pull of the nut usually removes the most obstinate wheel ; do not hammer too vigorously unless the flywheel is pulled in the opposite direction or the crankshaft may be damaged.

Removing the Crankpin. The crankpin is a taper fit in the steel balance weights. This is best forced out under a press, but can be driven out with a punch : the pin only requires forcing out about IV when it comes apart easily. Take care to catch the rollers.

Renewing Big End. Should the conrod be worn in the big end it is possible to rectify this by slightly lapping the bore, but this is a skilled job. If the wear is slight, oversize rollers will put matters in order. We stock rollers .0005" and .001" oversize. Should rod be worn too badly it will mean a new rod. We have kept the cost of this as low as possible, realising that one objects to buying an expensive component to rectify a little wear.

To Reassemble Big End. Take the crankpin, and after seeing that everything is perfectly clean place it into the balanceweight and force it down until the end comes exactly flush on the outside, making allowance for the slight recess on this face. Do not force beyond this or the flanges which guide the rollers will be crushed in and bind the latter. Now assemble the rollers, using a little grease to hold them in position and press down lightly. Set true either in a lathe or by revolving in the one half of the crankcase. When true, press down the balance weight until the end of the crankpin comes flush with the outside of the balance-weight. Whilst pressing down hold the side first fixed down on something flat to prevent forcing the crankpin further through. This is important or, as explained above, the rollers will bind endwise. The correct fit of crankpin in balanceweight is obtained when the outside face of the flange on crankpin lies level with the outside face of balanceweight. When put in by hand leave " to force down, if more than this the shaft will not come true.

To Reassemble the Engine. When the crankshaft and big end are assembled the most difficult job is finished. The crankshaft can now be put into the crankcase. The joint of the case should be smeared with some jointing compound—gold size will do—and bolted up. The oil pump can then be refitted.

The piston is then put on the gudgeon pin fixed with the circlip. When putting the circlip in, take care to see the ends are arranged to come near the slot, in order to facilitate its removal when required.

To Check the Alignment of the Conrod. Take a steel rule and place it parallel with the axis of the crankshaft on the cylinder face of crankcase, lower the piston down on to the edge of the rule. The piston, if rod is square, should touch both sides with equal pressure. If it does not, the rod may be set over slightly. At the same time, the position of the piston in the bore of the case where the cylinder fits should be checked. It should float an equal amount each side of the centre line. This is necessary to prevent binding in the cylinder and also damage to the big end.

Replace the cylinder, but first see that the cylinder base packing is in good order. Tighten the nuts up equally. See note re fitting of head under " Decarbonising "

Fitting Flywheel (Three-speed Models). First put on dynamo belt ; the dividing plate between the chain and belt is placed in position. Clean shaft and bore of wheel Make sure that not the slightest oil is left on these parts. Place flywheel in position and tighten up nut as tight as possible, using the special spanner provided, and finally lock up by using a hammer to drive the spanner round.

p26 engine