Primary chain and rubbers

[Sesman]

Hi, Bryanj. So I understand, but they seem fine. I’ll compare with the new replacements I’ve ordered, today.

Incidentally all the evidence suggests this motor has never been apart. Wonder if Mr Honda changed the rubber formula during production.

[Sesman]

Thanks delta rider. Do hope I haven’t triggered an oil debate  .

[Bryanj]

I doubt that those rubbers changed, heat cycles would affect more than age but age does it as well

[deltarider]

I can only share my personal findings. In the past I've used various oils. The one I disliked most, was the Mobil 1, in those days regarded as the very best. On the top of the Pyrenees at the French Spanish border, I detected leaks at the oil pump seals. Some months later a little smoke on decelaration indicated leaking valve stem seals. They have been replaced in an top end overhaul. Ever since I've used that Castrol High Mileage, I have had no further oil leaks (apart from the head). On the contrary: the notorious shifter seal which leaked a lot before, seems to have cured it self. Although Castrol seems to have abandoned the name 'High Mileage', some oil suppliers in their sites stress, it's still the same High Mileage oil. You may also want to read this: http://forums.sohc4.net/index.php/topic,187317.msg2171984.html#msg2171984
Note that these are my personal findings on my CB500. I cannot comment on the condition of the rubber parts in the engine: I've never set eyes on them.

[Trigger]

If the primary unit came apart very easy then the rubbers are worn. You will find this out when you try to reassemble the unit and find it tight. A smear of red rubber grease makes it easier to get it back together 

[Sesman]

Hi, Trigger. I very much appreciate your input. The drive needed a sharp downward rap Ona piece of softwood, then leverage. It certainly didn’t fall apart and needed persuasion. I’ve just received new replacements and will report shortly. Thanks again.

[Sesman]

Ok, new primary rubbers have arrived. Absolutely no perceptible difference between new and old. I think I’ll be returning them?

Slipper blade total thickness is identical the new one, apart from the cam chain side plate tracks. It does however have a cure of significantly greater radius than the new one. The new one is also slightly stiffer to bend…slightly I’d say.

Not sire how you extract the horseless rubbers out of the tensioner unit though?

[Trigger]

That don't make sense, unless someone has changed the rubbers recently without doing the chain as, a worn chain will feck rubbers and worn rubbers will snatch and stretch the chain 

[Sesman]

I know…bizarre, but this engine has never been apart. Nothing shows signs of disturbance.

I’ve taken one new rubber out of the bag and the two items are identical in feel when pressing, twisting and bending.

Must be some kind of miracle

[Sesman]

Meant to say. Oddly enough the tensioner bump stops were as hard as marble as predicted by oddjob. Think I’ll just replace the lot. Anybody want to buy some used, but perfect primary drive rubbers?

[Sesman]

I managed to pry them out with a pick. All reassembled now. I’ll keep the old stuff as you suggest as it’s got lots of service life. May save somebody’s build in the future.

Incidentally, just been quoted £300 + vat to blast the head, cylinders and cases ready for paint. That won’t be happening…Wow

[Sesman]

For,those who may be interested, images of new vs old hy-vo chain.

Original was a tm-hy-vo. Replacement claiming to be Kawasaki is a Morse.

[Sesman]

For my education, the chain supplied by msg is claimed to be an ‘original part manufactured by Kawasaki “. So ‘Morse’ is owned by Kawasaki?

I thought Morse was an American company? Is Morse a genuine Kawasaki primary drive chain part?

[K2-K6]

Kawasaki is a significant engineering company,  but wasn't aware of Morse ownership. Possible though.

Quite an interesting history though for the chain type, often referred to as "Morse" from multiple link plates effectively making a linear gear.
Think that Borg Warner transmission holds the rights to the "Hi-Vo" description as they developed it to that high velocity iteration from Morse foundation.  Tooth form etc was intrinsically part of that research and development.

[K2-K6]

Some thoughts on it here http://www.sohc.co.uk/index.php/topic,25001.0.html