Topic: CR750 part?

[Phil]

I was going through some of my CB750 stuff I've being holding over the years. I came across a bag of three cam chain guides. Part number 14611-300-970. As you can see in the photo, they are slightly different from the standard part. Could it be a CR750 part? Is it better than the standard one?

[turboguzzi]

just out curiosity googled that part number and turns out that it belongs to a CR kit, but for a completely different tensioner mechanism introduced in 1972, looks more like a CB500 mechanism with a spring compressing a curved tensioning slide.
im not a CR expert by any means, but this guys seems to be quite into them, the section picture in the third row is certainly very interesting....

https://translate.google.com/translate?sl=de&tl=en&u=http%3A%2F%2Fwww.tr4-rally.com%2Fmotorcr.html

[napoleonb]

It is indeed a proper CR750 part and as TG said for the later type of tensioner.
I have a NOS cylinder, chain and bracket that goes with this guide (which I also have NOS) but if you want to get rid off it...

[Phil]

I have 3 - all new. I have offered one to Carsten Conrad but if you can use one, let me know. Nice to have but absolutely no use to me as I shall be using Messnermoto parts.

Thanks for the information about the CR parts - all very interesting!

[bwaller]

Have I had my head in the sand for 45 years?? I think this is the first time I've see this tensioner system that is stated was made available as an upgrade to the race kits in 1974.

Has anyone held one in their hands?

[turboguzzi]

met today mirko while i was in milan and he thought that this also required a special cyl block.... i think he is right but dont know enough about 750s to spot the difference... see here

[MessnerMoto]

met today mirko while i was in milan and he thought that this also required a special cyl block.... i think he is right but dont know enough about 750s to spot the difference... see here

definitely special block. Also I think RC was using similar cam tensioner and also similar block ?

[napoleonb]

The cylinder block is quite different indeed, not only the machining but the casting as well.

[gschuld]

met today mirko while i was in milan and he thought that this also required a special cyl block.... i think he is right but dont know enough about 750s to spot the difference... see here

definitely special block. Also I think RC was using similar cam tensioner and also similar block ?

RC Engineering kept to factory spec regarding tensioners on their cast cylinder blocks.

I have one here.

George

[MessnerMoto]

the reason I did not make simple two guides tensioner design for my cam tensioner....
I could not make it without modification to cylinders and head..... that would be not a plug and play solution

...also interesting thing is that CR design is not supporting the chain in all the length on tension side... probably they did not have knowledge about importance 

[napoleonb]

@Phil I'm not quite sure if my private message came thru

[Phil]

I just received your message - have replied