Balance factor

[sheddweller]

I am considering having my motor dynamically balanced. Can anyone tell me the factory balance factor, and /or report on any factors used for sporty road use.

[simonnorthroad]

I had mine done by the last longstanding balancers Bassett Down who'd "never done a Morini before" and had no archive notes. Nor, I realised later, did they ask for my Primary/clutch components, which they should have.
The bike is pretty buzzy and harsh. Not sure it was a great success TBH

[3potjohn]

Bassett Down eh. When they were actually there it was about a 10 min cycle ride from my mum’s.
A long time ago now.
John

[Kamel]

Unfortunately I have heard some quite negative feedback about Basset Down.

[sheddweller]

Simon,
Thanks for your input. I don't have any concerns about the work of this company, based in Brisbane, and yes, they want everything that hangs off the crank. I was hoping that someone had some info about the balance factor these motors originally employed, as a starting position.

[smotorboy]

I think your best bet is to leave the factory crankshaft throw-weights alone, match up the piston/rods weights as best you can, and then have the primary gears, clutch basket, and Dynamo/flywheel spun balanced....

For the lowest bearing loading,,,, single cylinder engines use a 50% factor...

Old British vertical Twins and Harley narrow angle (45 degree) twins used up to about a 65% balance factor to change the vibration from up-down to fore and aft,,, which is much more pleasant for the rider.

Ducati (and other) wide angle twins (90 degree) can use a 100% balance factor as each cylinder can cancel the other....

72 degree twins are few and little information is available. I suspect that the 72 degree factor is some where between 65% and 100%, or it could be 50% to minimize main bearing loads...

If I find myself one day with nothing to do,,,,, it might be fun to set up the 350 Morini rotating assembly and determine an estimate of the factory balance factor...

Robert in California
Red Baron LSR

[simonnorthroad]

Bassett Down Balancing has changed hands at least once so whilst new owners of established businesses may have the founders' notebooks, no guarantee they will have the expertise