Engine
All bearings used on the machines are C3 grade of standard type except belt idlers and crankshaft mains. The mains are a wide clearance type. These are available from bearing distributors, as are all the other bearings. Do not use cheap C3 bearings. ( C3 relates to the clearance sizes within a hearing, it is NOT a quality specification) SKF and RHP are recommended makes. Oil seals are standard size single lip except for starter motor/crankcase seal. This is 7mm wide (standard 8mm) Recess in housing can be machined 1mm deeper to take 8mm seal. Double lip seals are recommended for forks and cam belt double pulley. If persistent oil leak on double pulley exists a baffle can be inserted in the pulley bearing. Persistent oil weep from filler plug on dry clutch engine covers cured by fitting longer threaded plug from model. Desmo shimming and carb setting print out available. Quality of alloy castings varies considerably. Cylinder head and inlet manifolds are susceptible to blow holes.
When raced hard little ends can break off. Over revving can cause cases to crack near the bottom pulley at the oilway to the front head causing oil to pump out. Repair by removing bearing carrier, bore through oilway and fit a 8mm cap-head bolt. This pulls crack together and is sealed with suitable glue/sealant. The bolt is then drilled to re-establish the oilway. Crossland oil filter code 673 can be used. Big bore kits can cause reduced compression ratio and negate their CC advantages if attention is not paid to the combustion chamber machining. Post 84 750 crank and pistons can be used for a conversion but the crancase mouths have to be opened out. 750 crank is considered to be better for this conversion than the 650 Alazurra crank due to the better balancing factor. Only later Pantah cases are suitable for a big bore conversion as they are considerably stronger. For a breather a standard plastic flapper valve from an automotive power brake vacuum booster (available at any auto parts store) can be used and run the outlet overboard. Appears to work just fine, except for the following issue: When the crankcase level is filled up to the “max” line on the sight glass, a lot of oil is blown out the breather (or somewhere in that area, it’s hard to pinpoint the source). This problem goes away if filled only to the “min” line, and a leak-down test indicated good health.