Cam Chain Tensioner Roller Refurb or replacement

[G-Man]

Because there was quite a bit of interest in the cam chain tensioner mods I did as part of my 1961 CB72 saga, I though I would pull out some useful pictures and thoughts into this new thread. The tensioner refurb idea started here in my CB72 restoration thread.

http://www.honda305.com/forums/1961-cb7 ... 1-574.html

In summary my original 'mod' was to grind off the original rivet for the centre pin and convert this to a bolted construction with an M7 thread cut into the pin.



I made a tool to hold the centre wheel so that I could re-true the degraded surface in my lathe.



The new M7 bolt has to have its head thinned to clear the aperture in the cylinder barrel and must be short enough not to block the oilway in the centre pin. When assembled, the oil holes in the centre pin and bush for the needle roller must face down so that the little oil scoop picks up oil falling down the cam chain tunnel and feeds it to the bearing.



Because of the poor state of most of the rollers, LM came up with the bright idea of re-purposing primary chain tensioner rollers. These have a different (plain bronze bearing) and need a bit of hand re-work of the tensioner arm to take the locating pegs of the centre pin. The centre rib of the wheel is too wide for the cam chain and must be thinned down.

[G-Man]

LM kindly gave me a bag of primary tensioner wheels and a small selection of tensioners so that I could 'perfect' the technique.



With a bit of work I was able to produce three tidy tensioners.



One of LM's tensioners was a later small-wheel tensioner with plain steel on steel centre bush.



Consensus is that these are later replacement parts from Honda as they come in all styles; left / right pinch bolt and wide / narrow flange.

When I was looking at these I started thinking about the Cappelini sprocket type conversion which is lovely but expensive. It was while I was looking for alternative rubber wheels I came across an idler 'sprocket' which was used on 900 and 650 Kawasaki DOHC fours. This part looked interesting so I bought a couple.

The sprocket is rubber mounted and has rubber lands for the chain to run on. It is the same diameter as the 'small' Honda wheel but the needle roller is a shade smaller than the Honda centre pin. A little bit of work is needed, but what a nice possibility?





More later..........

G

[Seadog]

Interesting. Can't wait to see how you'll make this work.

[G-Man]

Seadog

I just bough a small tool grinder for my lathe so I am either:

a) going to see if I can reduce the diameter of that centre bush OR
b) look at alternative needle bearings

Watch this space.

G

Interesting. Can't wait to see how you'll make this work.

[Seadog]

G, might there be commercially available idler sprockets that might fit the bill a bit better (e.g. http://chains.ustsubaki.com/viewitems/i ... ened-teeth)?

Seadog

I just bough a small tool grinder for my lather so I am either:

a) going to see if I can reduce the diameter of that centre bush OR
b) look at alternative needle bearings

Watch this space.

G

Interesting. Can't wait to see how you'll make this work.

[G-Man]

Seadog

Now you're making it too easy!

Food for thought.

G

[qguote="Seadog"]G, might there be commercially available idler sprockets that might fit the bill a bit better (e.g. http://chains.ustsubaki.com/viewitems/i ... ened-teeth)?

Seadog

I just bough a small tool grinder for my lather so I am either:

a) going to see if I can reduce the diameter of that centre bush OR
b) look at alternative needle bearings

Watch this space.

G

Interesting. Can't wait to see how you'll make this work.

[/quote]

[james robert]

Is there a way to mill your own sprockets.