Valve shims

Reunited Chris

Reunited Chris

Senior member
Location
Sydney
I recently read in a magazine featuring an article on Laverda's that the valve shims are a direct copy of a Honda motorcycle.
Can anyone verify this, know what Honda?
Also who/where is a good source for these shims in Aus.
 
Reunited Chris said:
I recently read in a magazine featuring an article on Laverda's that the valve shims are a direct copy of a Honda motorcycle.
Can anyone verify this, know what Honda?
Also who/where is a good source for these shims in Aus.
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I very much doubt it. I don't know of any public Honda using shims in 72-73 but I may be wrong.
Maybe the information passed on through decades relates to the big twins being "copied" on the CB 72 and 77.
Paul
 
Honda didn't use shims back then did they? They had locknut and screw tappets. They may have used shims in their racers but I doubt Laverda copied those.
 
In my experience Honda has never used shims which sit down over the tip of a valve
They have used flat shims and continue to do so.

I made my own for the few Laverdas I saw. The last of my stock was taken by a Christchurch based owner who I've never seen since.
 
GregT said:
In my experience Honda has never used shims which sit down over the tip of a valve
They have used flat shims and continue to do so.

I made my own for the few Laverdas I saw. The last of my stock was taken by a Christchurch based owner who I've never seen since.
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Thought the same... but it seems quite a few CBR 4-valvers use the valve tip type shim. But they're all 6mm, or thereabouts, so pretty useless info.

piet
 
Tippie said:
All the CBR6s I have seen have flat shims sitting in the valve spring retainer.
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Didn't recognise that from the parts diagrams Lee.

So what we actually need for an endless shim supply is new spring retainers? Pretty easy...

piet
 
The retainer has a recess the shim sits in - resting on top of the valve.The recess simply locates the shim laterally.
I've used aftermarket Ti retainers made for Nissan SR20 engines and using 10mm dia shims on a GS1000 Suzuki.
I'm sure a suitable retainer can be found -or spat out in numbers from a CNC lathe.

The current state of the art is buckets with an integral stem which bears direct on the valve tip.
They come in large kits for the engines using them. Clearance is set by swapping buckets.
I don't know if they are available in a suitable bucket size. The only ones I've seen fitted the Z1
and I think were again Nissan.
 
Surely Laverda must have used an existing car shim back in the day? I can remember Hesketh having shims made at great expense only to find out the motor was designed using British Leyand shims. I once saw a GS1000 that spat an exhaust shim straight through the head leaving a letter box shaped hole.
 
Exmoor beast said:
Surely Laverda must have used an existing car shim back in the day? I can remember Hesketh having shims made at great expense only to find out the motor was designed using British Leyand shims. I once saw a GS1000 that spat an exhaust shim straight through the head leaving a letter box shaped hole.
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Probably not. Most car valve stems back then were at least 8mm, 7mm was quite unusual.

Even if it were a car shim, would probably also be obsolete by now....

piet
 
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