AboutBill Silver Expertise Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.
Experience I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.
Organizations VJMC (Vintage Japanese Motorcycle Club) of North America
Publications VJMC newsletter, as editor for two years and as contributing editor currently.
Question Hello Bill,
What is the simplest process for adjusting the cam chain on a 79 cb 750k? Is this a simple enough process that an average mechanical mind can do?
Both tensioners are spring loaded, but the crankshaft/valve positions will either aid or hinder chain adjustment. The crankshaft should be towards a TDC location on 1-4 cylinders or slightly after. The nut on the back of the cylinders needs to be loosened enough to allow the tensioner to adjust itself. Lock the bolt back down again.. gently. You can turn the crankshaft back and forth about 10-20 degrees and feel if there is some slack in the rotation (requires removal of the right side alternator cover). If the chain is tight, then you won't feel any slack between forward and reverse turning directions. The exhaust cam runs off of the intake cam, with its own tensioner. Loosen the tensioner lock bolt and let the spring tension do its job, hopefully.
The guess and try method would be to loosen the tensioner bolts, tighten again, start the engine and see if it is quieter or not. If so, you are done. If not, try it again...
The absolute best way is to remove the cylinder head cover and observe the parts in action. Unfortunately, that will probably require new cover packing, bolt seals and some RTV sealer to seal up the corners where the packing end plugs drop into the cylinder head recesses, so that gets a bit more complex and messy.
I don't know if this was as helpful as you hoped. Not knowing your extent of mechanical experience probably leaves more questions than answers. If the bike has over 40k miles on it, the chain may well be stretched beyond adjustment. The chains are endless link-plate types, so difficult to replace without a major teardown.
