Montesa M7 case screws: Why??

[farmer58za]

Hi All

Is there an underlying engineering reason why Montesa adopted M7 case screws and bolts for their engines? Or did General Franco's cousin have a huge shipment of the things going for a "very special price" ?

Regards
David

[Mike52]

Why did the Russians invent their own metric thread system for the Belarus tractor.
To piss off anyone trying to fix them or because they could ?
Ah the mysterys of life

[David Lahey]

While we are having a bleat about Montesas how about:
The cylinder hold down nuts being an odd size internal hex
The gearbox output sprocket being mounted on a taper
The primary gear being mounted on a taper

The M7 thing is not confined to Montesas either, I seem to recall that OSSAs have them too

[farmer58za]

Ah, Franco's cousin was in there too...........

The M7 thing is not confined to Montesas either, I seem to recall that OSSAs have them too

[mx250]

I though M7 must be the perfect size giving strength, durability and weight.

[dutchtwinshock]

M7 is a normale size italy france and spain
You can get them in every homeworkshop

[Davey Crocket]

YZA's and B's (250/360) use 7mm bolts in the cases around the crankshaft....extra stenght around the crank I guess without having to make the cases thicker if they went to 8mm.

[Slakewell]

KTM use them on sprocket bolts