Motorcycle Repair: ct90 cam tensioner 1966 and 1972 engines, fiche section, proper tension

Question
I am moving the engine components (piston, cyclinder, head assembly)from a 1972 CT90 with a destroyed tranny onto a 1966 engine body with a good tranny. The cam tensioner is different on the two engines.  the 1972 has the spring loaded mechanism which is quite easy to understand and adjust.  Trying to understanding how the 1966 system works..I am guessing the plunger must work via oil pressure and is there a test to ensure its working properly and keeping proper tension.

Answer
Mike, you are correct. It uses a light spring to keep things in place, then uses the oil flow from the pump to reinforce the tension on the plunger.

http://www.houseofmotorcycles.com/fiche_section_detail.asp?section=143151&catego...

That system tended to not keep the chain in tension, especially when the chain began to stretch, so they added more spring tension and a method of adjusting the tension to the original design.

http://www.houseofmotorcycles.com/fiche_section_detail.asp?section=143450&catego...

I don't know of a "test" in particular. If you are using the later model parts, you can sort of check tension by rocking the crankshaft back and forth using the rotor bolt, feeling for chain slack between the crankshaft and camshaft. If the chain is very slack, you should replace it first.

When the camchains are loose, they make a slapping sound and bits of metal show up in the oil when you are changing it and cleaning any associated parts.

Bill Silver