3CL pistons marked Cann 75

[paulincayman]

Rusty, your pictures are inspiring! Thank you.

 

[Dellortoman]

" Centre punch, drill and tap to M6."   


What do you do with your 7mm bolts? 

Are they M7? If so I stand corrected.  I didn't drill and tap mine so I was only guessing.

 

[Vince]

So are rear-wheel adjuster bolts and exhaust studs. Not exactly a common size.

 

[piranha-bro2]

And SF sidecover screws ... and tappet adjusters (I think!).

 

[Rusty Spokes]

Rusty, your pictures are inspiring! Thank you.

Paul, No hay nada que agradecer. Be safe

 

[Paul Marx]

And SF sidecover screws ... and tappet adjusters (I think!).

And practically all the bolts and studs on singles, and exhaust studs on a lot of Laverda.

Paul

 

[Ventodue]

So are rear-wheel adjuster bolts and exhaust studs. Not exactly a common size.

7mm is a 'second choice' or 'non-preferred' size under the two relevant ISOs (261 and 262, "General purpose metric screw threads").

But preferred or not, the Italian motorcycle industry seemed to like it ... 

 

[sfcpiet]

7mm is a 'second choice' or 'non-preferred' size under the two relevant ISOs (261 and 262, "General purpose metric screw threads").

But preferred or not, the Italian motorcycle industry seemed to like it ... 

Very common on German vehicles as well.  Post-war BMW and NSU cars have dozens of them.

May be a "second choice" these days, it was a very common choice where M6 was insufficient but M8 too large back then.  The size is used in just such applications on Laverdas, some were later changed to M8 (supplementary head studs on early 750s) as requirements changed.

piet

 

[paulincayman]

Back my cam wheels,
thanks again Cam for that encouraging and comprehensive description ,  and for all the helpful replie as I said previously its a very steep  learning curve. Redrilling sounds quite doable with some care and attention .
  Next mystery.. according to the green book when fitting the cam wheels the little  punch mark  on each wheel  should be facing the mounting flange face, wheel A =inlet , wheel S exhaust..  mine of course has to be different,    wheel A is on the exhaust  cam and installed with the punch mark away from the flange  face so it is back to front as well on the wrong cam ,  the S wheel is on the inlet cam with punch mark facing in towards flange so it is mounted correctly albeit on the wrong cam . Has any one seen anything like this before? was wondering if it was a cunning attempt to retime the valves for the 4c cam. ?  I'm only asking out of curiosity as I will be re drilling the wheels as per instructions , that way I'll know where I'm at from the get go.
PS Happy Easter.
Paul
 

 

[breganzane]

Too hard to guess really, you'll only know when it goes back together and you time it up. But from the drawings, the a11 holes are offset 4deg and that's 8 crank deg, so no amount of flipping and swapping will get that close to in line with the tooth.
It might be worth checking the thickness of your head though, if it's been skimmed then that affects the cam timing.  Head should be 94.0mm.
Cheers
Steveb

 

[Rob]

was wondering if it was a cunning attempt to retime the valves for the 4c cam. ?

Probably.  Flipping the sprocket is not unheard of.  Nor is making your own timing marks.  As those with loads of experience will tell you, Laverda cam timing was sometimes not very accurate ex factory.  I remember Phil Todd saying he's found one bike 23 degrees out!
https://www.laverdaforum.com/forum/index.php/topic,54311.msg101459.html#msg101459

 

[piranha-bro2]

I know that dialling cams in is a good practice when building motors, but is there a particular reason the factory produced different cams that required different cam sprockets??? Why would they make them in such a way that a std pair of A and S cam sprockets weren't basically correct - and at least close enough that a bit of slot work with a file got them spot-on? Non comprendo.