V75/VA 250 cylinder differences

[JC]

Can anybody (Jared??) tell me if there was any difference between the V75 & VA250 cylinder porting? Like wise the pipe.

[cappra]

Porting was the same on both models, however, the exhaust bridge was eliminated on the VA
and the exhaust port was enlarged to a more oval shape.  It is the best flowing of the VR/V75/VA
series.  Pipe was the same as the V75.  The 360VA pipe looks the same, but on closer examination,
the centre section is larger.

[JC]

Thanks Jared.

I tho't the unbridged ex port came in on the V75 & that bridged ex was only on VRs. Was I wrong?

[cappra]

I can't be 100% certain, but going by the parts books, the V75's
starting from 73M8089 call for the same cylinder liner (7360.027) as the
earlier VR's.  Starting at 73M9690 which would be the 1st VA model, the
parts book calls for the cylinder liner part number 7360.02702.
What is somewhat confusing, is where is part number 7360.02701? liner.
Montesa usually adds a 01 or higher number at the end of the part number to
indicate a different part or an upgrade to a specific part, although this is not
true all the time.  For anyone interested, here is how Montesa breaks down it's
parts numbering system.  Example:  7320.204 -
73 is the model prefix (250mx)  20 is the frame group, and 204 is the individual part number (rubber hold down strap)
Here are the groups
20-frame
30-front fork
35-lower fork
40-rear suspension
50-wheel and hubs
55-brake
60-engine
61-ignition
62-carburetor
63-clutch
64-transmission
65-kickstarter
66-gearbox
70-lighting
80-speedo and horn
87-tools
90/99-nuts, bolts, seals, bearings etc

so, 2160.011?   (Cota 247 rod bearing)

and now you know the rest of the story........
 
                                                 

[JC]

Thanks Jared. Very interesting.

Also interesting, the 75 250 enduro also uses 7360.02702 liner - same as VA.

According to mag tests of the day, VA made gobs of power everywhere - low, mid, hi

[cappra]

Yes.  The VA 250 had the sweetest motor of the three. 
Except for the trans, flywheel, aux weight and 3mm more length
on the intake side of the piston, the enduro motor was all mxer!
At the Montesa shop that I worked at, we sponsored a local
lad on a VA250.  When he hit the trail to follow the Nationals
he took two spare motors with him.  You could buy a new motor (minus carb)
in the box ready to go for $500 USD.