Transmission chain omission no more..

[Sir Sidney Ruffdiamond]

Just fitted new rubbers on my Corsa clutch - and replaced the single chains ( new chain had much less deflection both worn similarly - old rubbers were a bit barrel shaped - new ones needed a little oil and a rubber mallet - new gaskets from Phill Todd , rubbers from Wolfgang

 

[Andy]

I was impressed at the difference new rubbers made. Previous owner appropriately referred to the bike as “the chaff cutter”, that changed with new chains and rubbers.

 

[Paul Marx]

Be careful punching the rivets out.
It's easy to split the post.
I also follow Piet's recommendation and ease the rivet by drilling it.
Paul

 

[CLEMTOG]

I have never ground off the rivets without first stripping the components and doing it on the bench/drill stand. I have used heat in one form or other, propane lamp, or the kitchen oven (but only if it is clean enough to eat off) perhaps there is a difference in running simplex chains on the factory supplied two row sprockets over using the outside ones on the earler three row type? I have seen them broken but dont remember much about the sprockets, I know it has happened but I have never seen a broken triplex and I dont think there has ever been a broken duplex reported, the factory race bikes (some) used quadraplex chains with a spacer in the primary chain case and most likley a different end on the crank, unless the four row sprocket was "dished"
CLEM

 

[sfcpiet]

I have never ground off the rivets without first stripping the components and doing it on the bench/drill stand. I have used heat in one form or other, propane lamp, or the kitchen oven (but only if it is clean enough to eat off) perhaps there is a difference in running simplex chains on the factory supplied two row sprockets over using the outside ones on the earler three row type? I have seen them broken but dont remember much about the sprockets, I know it has happened but I have never seen a broken triplex and I dont think there has ever been a broken duplex reported, the factory race bikes (some) used quadraplex chains with a spacer in the primary chain case and most likley a different end on the crank, unless the four row sprocket was "dished"
CLEM

I've managed to break a triplex...

Last turn, last lap Sunday afternoon at Spa, 2012. At least I got my moneys' worth of the participation fees.

Turned out it was a 2nd. rate chain, at best. Duplex Iwis fitted since then. Can't actually go back as I removed the outer row of teeth on both sprockets, while I was at it... Happily, the primary cover was salvaged thanks to some clever laser weding.

Here's the crank stub of the works triples that used the 4-row chain, Clem. Completely different clutch sprocket to be seen lower right.

piet

 

[Paul Marx]

I've managed to break a triplex...

Last turn, last lap Sunday afternoon at Spa, 2012. At least I got my moneys' worth of the participation fees.

Turned out it was a 2nd. rate chain, at best. Duplex Iwis fitted since then. Can't actually go back as I removed the outer row of teeth on both sprockets, while I was at it... Happily, the primary cover was salvaged thanks to some clever laser weding.

Here's the crank stub of the works triples that used the 4-row chain, Clem. Completely different clutch sprocket to be seen lower right.

piet
View attachment 87732

Without a "tensioner".
Also used on some twins though I can't find the reference.

 

[sfcpiet]

Without a "tensioner".
Also used on some twins though I can't find the reference.

Only used on the '73 works engines. These also used a duplex chain! All other 750s had tensioners.

piet

 

[LAVERDA54]

I've managed to break a triplex...

Last turn, last lap Sunday afternoon at Spa, 2012. At least I got my moneys' worth of the participation fees.

Turned out it was a 2nd. rate chain, at best. Duplex Iwis fitted since then. Can't actually go back as I removed the outer row of teeth on both sprockets, while I was at it... Happily, the primary cover was salvaged thanks to some clever laser weding.

Here's the crank stub of the works triples that used the 4-row chain, Clem. Completely different clutch sprocket to be seen lower right.

piet
View attachment 87732

 

[sfcpiet]

Just fitted new rubbers on my Corsa clutch - and replaced the single chains ( new chain had much less deflection both worn similarly View attachment 87730View attachment 87731- old rubbers were a bit barrel shaped - new ones needed a little oil and a rubber mallet - new gaskets from Phill Todd , rubbers from Wolfgang

OE cush rubbers were slightly barrel-shaped! Most aftermarket ones are simply cylindrical...

piet

 

[MarnixSFC]

Only used on the '73 works engines. These also used a duplex chain!

That engine is the only 1973 SFC engine that I know with a duplex chain, which is almost certainly one of the mods that were done later, most likely by Roberto Gallina. All the other engines that I saw had the traditional triplex chain, in combination with a similar chain guide, but which of course was 3 row and was always made of steel.
With all the engines that I have seen, there is not much hope left of ever finding one with the unique alternator still present, but I won’t stop searching, still hoping for a miracle.

Marnix

 

[sfcpiet]

That engine is the only 1973 SFC engine that I know with a duplex chain, which is almost certainly one of the mods that were done later, most likely by Roberto Gallina. All the other engines that I saw had the traditional triplex chain, in combination with a similar chain guide, but which of course was 3 row and was always made of steel.
With all the engines that I have seen, there is not much hope left of ever finding one with the unique alternator still present, but I won’t stop searching, still hoping for a miracle.

Marnix

Marnix,

Sorry, somehow I missed your reply.

The slippers were not retro-fitted, or Roberto built this particular engine from un-finished cases. Unlikely, but possible.

Neither the bore for the tensioner pivot nor the bore for the adjuster screw are machined, this engine has never had the conventional tensioner fitted.

piet

 

[MarnixSFC]

Piet,
That's not what I tried to explain.
All the chain guides that I have seen were as in the picture in my previous post, made of steel and for triplex chains. No slipper tensioners were used in combination with the guide, so indeed there was no hole drilled in the lower crankcase half for the slipper tensioner.
Two holes were drilled and tapped for the guide though, one with M12 thread where normally the spindle for the slipper sits and a second M8 hole for the the other mounting bolt of the guide.

Marnix