The Service Dept

THE SERVICE DEPT

JODY NICHOLAS

EPOXI-PATCH REPAIR

I just read Stan McConnell’s problem with the broken 750 Honda chain (June '72). The chain on my 1969 750 broke and went through the cases at about 15,000 miles. I was quoted $400 to have it fixed. This is too much, so I formed a thin (1/16-in) aluminum plate over the 3 x 2-in. hole and epoxied it in place. First I cleaned everything thoroughly with Methyl-Ethyl-Ketone (MEK), then cooked the repair with a heat lamp overnight. In the morning, the hole was beautifully patched. I suggest using a minimum of epoxy for a first coat, then filling with a second coat.

I now have 24,000 miles on the bike, including two hard trips across the Mojave Desert at 100 mph+. There has been no leakage whatsoever from the patch.

Incidentally, this is my sixth bike. After a total of about 125,000 cycle miles. I’m convinced the Honda 750 is the epitome.

Terry S. Zaccone San Jose, Calif.

The repair you effected on your CB750 is often possible on a crankcase if the break was a minor one like yours. I say minor because the area near the transmission shafts and bearing areas wasn’t disturbed when the chain slapped the case.

Materials like Epoxi-Patch, which is available through Webco dealers, is excellent for repairing a great number of metals and plastics, and is very strong when mixed and cured properly.

With an engine like the CB750’s, you can remove the sump cover, flush out the pieces of aluminum with a solvent, and be reasonably sure that your engine hasn’t been contaminated.

OVER-OILER

Recently I purchased a ’72 Kawasaki 350 S2 (three-cylinder). Ever since the purchase, the bike smokes exclusively out of the right cylinder, resulting in fouled spark plugs. The dealer has been earnest in attempting to fix the bike.

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Kawasaki S2 owners have experienced the same problems you’re having. In an attempt to cure the over-oiling tendencies of the S2 model, Kawasaki has made two modifications to the oil pump, and seems to have cured the ailment with the second modification. The second possibility is pretty re-

mote but it’s worth talking about. The oil pump is divided into two cavities to feed the three oil lines:

Tom Green Milan, Ohio

left and center cylinders comes from one cavity and the line for the right cylinder comes from another. There is an O-ring between cavities which could be damaged, supplying the right cylinder with an over abundance of oil. The most logical explanation seems to

be that the outer crankshaft seal on the right side is damaged, allowing oil from the transmission to be drawn into the right crank chamber by suction when the piston rises, and then being burned along with the fuel/oil/air charge. Many two-cycle engines have a seal arrangement of this type, and when the cylinder nearest this seal begins using a larger amount of oil than its mate(s), the seal

The most logical explanation seems to be that the outer crankshaft seal on the right side is damaged, allowing oil from the transmission to be drawn into the right crank chamber by suction when the piston rises, and then being burned along with the fuel/oil/air charge. Many two-cycle engines have a seal arrangement of this type, and when the cylinder nearest this seal begins using a larger amount of oil than its mate(s), the seal should be immediately suspected.