REMOVING/INSTALLING OUTER CRANKSHAFT BEARINGS
3. Inspect the reed stopper height. Using a caliper, measure the distance from the seat to the bottom outer tip edge of the stopper. Measurement must not exceed speciﬁcations. If measurement is not within speciﬁcations, either bend or replace the reed stopper.
INOTE: The end bearings are not pressed onto the crankshaft. The bearings can be removed simply by sliding them off the crankshaft.
4. Inspect the reed-to-seat clearance. Using a feeler gauge, measure the clearance. Clearance must be less than 0.20 mm (0.008 in.). If clearance is not within speciﬁcations, replace the reed valve. 5. To assemble, place the reed valves on the cage with its clipped corner positioned to the lower n'ght hand corner of the cage. Place the reed stopper assembly into position and secure with the screws coated with red Loctite #271.
INOTE: Install the bearings by sliding each bearing onto the crankshaft making sure the dowel-pin hole in the outer race is properly positioned and will align with its hole and pin in the crankcase.
REED VALVE ASSEMBLY
1. Inspect the reed valves, stoppers, and valve blocks for cracks or any deteﬁoration.
Measuring Critical Components
INOTE: Critical engine specifications charts can be found at the beginning of this section.
CYLINDER HEAD VOLUME (Squish-Gap Method)
To check the squish gap, a micrometer and a heavy piece of solder will be needed. 1. Remove the spark plugs from the engine.
2. Wash the reed valves, stopper, and cage assembly in paﬁs-cleaning solvent and blow dry.
2. Insert the solder piece down through the spark plug hole and push it up against the inner cylinder bore towards the MAG-side of the engine. 3. Pull the recoil rope and crank the engine over several times while the solder is being held ﬁrmly in place. 4. Remove the solder from the cylinder. Using the micrometer, measure the very end of the squeezed solder piece. Record the reading. INOTE: If the solder hasn’t been squeezed by the piston, a larger piece of solder must be used. Repeat procedure.
5. Using the opposite end of the solder piece, insert it down through the spark plug hole towards the PTO-side of the engine. Push on the solder until it contacts the inner cylinder bore.
PISTON SKIRT/CYLINDER CLEARANCE
1. Measure each cylinder front to back about 2.5 cm (1 in.) from the bottom of each cylinder. 2. Measure the corresponding piston skirt diameter at a point 1 cm (0.394 in.) above the piston skirt at a ﬁght angle to the piston-pin bore. Subtract this measurement from the measurement in step 1. The difference (clearance) must be within speciﬁcatlons.
6. Pull the recoil rope and crank the engine over several times. Remove the solder from the cylinder and measure the squeezed end with a micrometer. Record reading and refer to the chart. INOTE: Measure from PTO to MAG-side of the piston to accurately measure the squish gap. Never measure across piston, exhaust to carburetor side, as the piston will rock and the reading won’t be accurate.
Readings may vary from side to side. Make sure the smaller reading is within the speciﬁcations listed. CYLINDER TRUENESS
1. Measure each cylinder in the three locations from front to back and side to side for atotal of six readlngs.
PISTON-BING END GAP
1. Place each piston ting in the wear pOItion above the exhaust pOIt of its respective cylinder. Use the piston to position each ting squarely in each cylinder.
2. Using a feeler gauge, measure each piston-n'ng end gap. Acceptable ring end gap must be within speciﬁcations.
2. The trueness (out-of-roundness) is the difference between the highest and lowest reading. Maximum trueness (out-of-roundness) must not exceed speciﬁcations.