Laverda Tiddlers cam and crank questions

C

chris78jota

Senior member
Location
England
Hi, some questions about tiddler camshafts on my 1953 and 1954 bikes:

Q1 - the 1953 engine came with a cam marked " S " - photo attached - I'm suspicious this has been falsely marked as a Sport cam by some impish person as it looks a very similar profile to a turismo cam. Can anyone clarify this from my poor photo (sorry) or is there some other way to measure it?

Q2 - The later crank on the left has a CFM conrod (with helpful casting logo :D) and crankpin. The earlier one looks like it has been rebuilt at some time and has a crankpin marked DE-MI, and has been engraved DE-MI 977.4. Anyone know what this means? It doesn't seem to match any of the dimensions of the crank or rod.

sorry for the really obscure questions but some-one might know! (any1)

Thanks, Chris
 

Attachments

  • rsz_1p1010014.jpg
    rsz_1p1010014.jpg
    54.8 KB · Views: 43
  • rsz_p1010017.jpg
    rsz_p1010017.jpg
    33.9 KB · Views: 30
Last edited:
Chris,

Cannot identify the cam, sorry.  But the 100 Sport and Tourismo cams show only very slight differences.  Check lobe height, may give a clue.

Apparently conrods were available from several aftermarket suppliers, I think I have 4 diffent 100 rods, all dimensionally the same.  Difference between 75 and 100 rods is the small end bush, 13.5mm for the 75, 14mm for the 100.  As far as I can see both have the same length.  Seems the earliest 100s were based on the 75 engine, ie, 75 barrel but with larger 100 liner fitted.  These are identified by the barrel studs in the open and smaller finning, the later barrels had enclosed studs.

Looks like the CMM rod is missing its' bush.

piet
 
I don't know anything about Laverda tiddlers so this is pure speculation.
There appears to be only one lobe on the cam, so I assume there are two such cam wheels in the engine.
That lead me to think that the "S" stamp on the cam might refer to "scarico" (exhaust).
Does the other cam have an "A" stamped on it? Aspirazione (inlet)
 
chrisk said:
Oh, I think the one in front of the picture was Demi Moores crank ......... (oh, a nasty thought just entered my mind :-X )
Click to expand...
Nah it can't be - my rod would be a much sloppier fit  :-[


Dellortoman said:
I don't know anything about Laverda tiddlers so this is pure speculation.
There appears to be only one lobe on the cam, so I assume there are two such cam wheels in the engine.
That lead me to think that the "S" stamp on the cam might refer to "scarico" (exhaust).
Does the other cam have an "A" stamped on it? Aspirazione (inlet)
Click to expand...
By jove, I think you might have it!  I don't have the other cam unfortunately, but this is indeed an exhaust cam.  My 1954 cams aren't marked, (other than the line at 90degrees which is actually a timing mark) but perhaps by then the factory thought there was no point marking them as the cams look pretty different and people would have got used to them?

I've measured the cams as Piet suggested and there is very very little difference in height so it must be a Turismo cam  :(
The wheelies will have to wait for the nitrous kit I suppose....

Chris
 
In the several Tourismo and GT spec 100s I've seen the cams have only been marked with the lined mark for the timing. The "S" markings have always been stamped on the hotted up on the Sport spec bikes. The D19 spec cams as supposedly used in the factory bikes are a complete different animal altogether with regards to lift and timing.

Tom
 
You must log in or register to reply here.
Back
Top