Motorcycle Repair: Honda CB77 crankcase hairline cracks, honda cb77, hairline cracks

Question
Hi Bill, you very kindly answered my query regarding stripping CA77 rear shocks - thank you. Another question. I have a CB77 with what looks like many hairline cracks in the casting of the bottom half of the crankcase (when viewed from the front). These go from side to side about two inches below the joint of the upper and lower crankcase. I've stripped the engine and the cracks don't appear to go though to the inside.  Just wondered if I need to worry or should I think about trying to have some welding done. There is no oil leaking through these cracks and the rest of the engine is pretty good. The kickstarter side outer engine cover had some definate cracking which I have had welded. I was told by a UK company (Govnors Bridge Motorcycles) who specialise in old Japs that "they are all the same".

Thanks - kind regards

Paul Lowsley

Answer
Paul, these engines are die-cast, at least the crankcases are. I have seen a lot of unusual markings that are from the die molds, not actual cracks in the material. If you are convinced that they are cracks, have a machine shop use dye or other crack inspection methods to ensure that the cases are sound. Lower cases are not known to crack unless you damage the engine mounts, spit a chain through the left side or misassemble them by not having all the alignment dowels installed correctly.

Kick starter covers come in two flavors. Early ones had the cable holders out in between the two mounting screw holes, somewhat unsupported. From around 1965, they move the cable mount about an inch forward, giving more support. This move requires an angled cable holder to match the changes.

Kickstarter covers often do crack and break. People fail to lubricate the k/s gear shafts, let some of the screws fall out or loosen, put the wrong bolt in the k/s arm which can dig into the cover and fail to keep them tuned and running properly, causing owners to excessively jump up and down on the k/s arm until the case breaks.

I have restoration guides with tons of information on them, all on CDROM.

Bill Silver www.vintagehonda.com