- Disassembling the engine & Cleaning the parts
- Disassemble the dismouted engine completely. About details, watch the service manual. It is necessary to get a parts list and a service manual for assembling and disassembling. You can get them at a Honda shop. Use an impact screwdriver to remove the Phillips screws or you will strip the heads. The man of a motorcycle shop uses T wrench to loosen the screw. He applies oneside of the bar to the top of the screw and hammer on another side so the screw loose because of the shock. The valve lifter is a bar clamp. I bored through the side of the adapting pipe which is only a piece of pipe. From this hole you can put out the cotters by means of tweezers. I bought a puller at Hayashi which is an expert shop of Monkeys. It costs 1650 yen.
- Gasket papers stick on the edge of crank cases and case covers. Scrape them off or oil leak occurs after assembling. Be careful not to make a scratch on the surface.
- Wash every disassemble parts in kerosene by means of brush. After washing, blow off kerosene with an air blaster. If the parts are very dirty wash twice in clean kerosene. Especially, wash bearings with rotation carefully. It prevents the sand to get into the bearing. If finished, store them in a vessel with a lid.
- Offset the engine
- To offset the engine 10mm right, cut off the engine fitting portions of the crank case. The width is sufficiently wide so the strengh is enough if it is done. Join two crank cases together and fit them with bolts. Engine fitting portion is two, and draw the cutting lines using a Magic Marker. The shapes of the portions are not flat so paper tape is available. Fit the tapes to the crank case shapes and draw the lines.
- Cut off the portions along the lines by means of a hacksaw. You can't cut off all so stop halfway or you'll cut other portion. This cut lines are guides to the next process so cut off straight and accurately. Mask the crank case with package tape not to be cut other portions.
- Attach a cutter for aluminum to a die grinder and grind the crank case along the cut lines. If you over-grind the case you'll make a hole so grind toward the under surface carefully. Before reaching to the under surface, change the cutter to spherical shape cutter and make the corner round. Wear safty glasses to protect your eyes because chips are very sharp.
Make two spacers the size of D16 X D9 X L10 by means of a lathe. Use S25C or STKM13A. These are the offset collars attaching to the left side of the engine mounting shaft.
- Sandblasting the engine parts
- The outer side of the aluminum engine parts are painted but if they are old they may be rusty, so clean them by means of a sandblaster. After blasting you may paint them. I did not paint the aluminum parts. I blasted crank cases with #30 sand and crank case covers with 80 micron glass bead. My blasting box and nozzle are handmade but you can buy a nozzle cheap so I recommend to buy it.
- You should mask the portions which you don't want to blast with package tape including strings. Cut off the tape along the edge carefully using a cutter. Mask other portions lest sand should enter into the bearings.
- Sandblast them and clean the surfaces. It is very difficult to see in the box because of dust so sometimes, put them out to confirm the finish. Use dust-proof mask while blasting for your health.
- Take off the tapes and wash the parts in clean kerosene. Especially clean the bearings rotating lest sands remain in them. After washing, blast with an air blaster. At this time, if the bearing doesn't rotate it must contain sands so wash again.
- Screw a head-cut bolt in the cyclinder head side cover and attach it to the electric drill bit by the vise. Rotate the drill and polish the surface by means of #250 Scotch Brite attached to a wooden block.
- Mask the cylinder with masking tape and spray on it with black heat-resisting paint.
- Assembling the engine
- It is better to order oilseals, O-rings and gaskets according to the parts list before disassembling the engine. And other worn parts should be replaced at this time too.
I changed all visible steel bolts to stainless steel bolts. Order the bolts after disassembling the engine and measuring the length. I orderd stainless steel hexagonal headed bolts. It costs around 1000 yen. - If the valve sheet is worn, valve fitting is necessary. When assemble the valves you should compress the springs by means of a valve spring compressor and attach cotters. At this time, be careful to attach them to accurate place; fit the convex to the concave. After assembling, hammer the top of the valve spring retainer softly to attach the cotter firmly.
- Be sure all parts are clean and start to assembl the engine. Oil the internal parts with engine oil and assemble them according to the service manual.
