More finds from inside the SF1 engine

Tippie said:
Yes they start as smooth round wheels with two raised sections to go between the runs of the duplex cam chain. They end up looking toothed after not very long, but I have found that the SFC items with needle rollers in them last far better.
Olly, have you checked the primary drive sprocket on the crankshaft left hand end yet?
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I reckon a steel sprocket as a tensioner wheel would be better than that crappy looking plastic roller. At least it wouldn't wear as quickly.
 
I brought a SF3 basket case in Melbourne back in the late 70s that had a set of steel sprockets in place replacing those nylon jobbies.
May even still have them somewhere in a box as I didn't reuse them.
 
If the chips from the nylon wheels are fine enough to get through the oil screen they can also block the oil hole in the rocker arm and deprive the cam lobe of oil from there. There must have been a reason why the factory used nylon instead of metal, despite the way they wear.
That rh crankshaft bearing looks like the spring from the seal got tangled up in it, maybe someone did a bad seal replacement at some time and ended up with the spring loose in there, they don't generally fall out of oil seals.
 
Tippie said:
If the chips from the nylon wheels are fine enough to get through the oil screen they can also block the oil hole in the rocker arm and deprive the cam lobe of oil from there. There must have been a reason why the factory used nylon instead of metal, despite the way they wear.
That rh crankshaft bearing looks like the spring from the seal got tangled up in it, maybe someone did a bad seal replacement at some time and ended up with the spring loose in there, they don't generally fall out of oil seals.
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I know we can't be certain but so much on the engine looks like it's never been taken apart. It could well be the original bearing. Hopefully one of the laverda specialists out there will have a good replacement for the tensioner wheel. I'm all for something sacrificial - but there are limits!
 
Plastic tensioner wheels vs steel: how about
- better damping
- less chain wear
- less vibrations
- less noise
- less cost
Just replace them every once in a while, probably together with the chain.

You may turn a set yourself from nylon or delrin stock, in that case an upgrade to those needle bearings would be a nice touch.

Tom
 
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TomL said:
Plastic tensioner wheels vs steel: how about
- better damping
- less chain wear
- less vibrations
- less noise
- less cost
Just replace them every once in a while, probably together with the chain.

You may turn a set yourself from nylon or delrin stock, in that case an upgrade to those needle bearings would be a nice touch.

Tom
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Replace a 750 cam chain?

Paul
 
Hmmmmm..... I did replace mine as it was certainly knackered. Sold the bike later and no idea how long it should last. Given the size of that duplex monster it will probably last very long but nothing lives forever. And then there's riding style, oil, maintenance...

Made a nice belt out of the old one, it looked pretty cool and given the slack it wasn't uncomfortable either. Still have that somewhere.

Tom
 
yust a question, how is the material spec. of the plastc rollers, maybe there a more advanced now on the market,
 
andre g said:
yust a question, how is the material spec. of the plastc rollers, maybe there a more advanced now on the market,
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Hello André,

whatever was used by the factory back then will hardly be of any interest today - materials have changed a lot. There should be better materials around nowadays.

I know that Uwe Witt made a batch of cam chain adjuster rollers, don't know though, which specification the material was he used ...

Cheers

Jo
 
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