Pros and Cons of 58/110 crank vs 58/107

[phil23fair]

I am in the process of getting the bits together to build an iron barrelled ported 225 motor with 30mm carb and expansion box. I've never used anything other than a 107 crank rod when building an engine. The idea of being able to move port timings about does seem a good idea but how much of a job is it really to get the base packer and cylinder head gaskets right to give the correct cylinder height and squish. Does it involve a lot of special packers and gaskets or is it all pretty much off the shelf stuff and is it really worth all the effort.

[Meds]

You can use off the shelf packers and gaskets.
A standard set up, 58x107 with a 39mm piston - gives TDC, 29+107+39= 175mm from crank centre, BDC -29+107+39= 117mm
Your projected set up 58x110, 39mm piston- Gives TDC, 29+110+39= 178mm from crank centre, BDC -20+110+39=120mm
This allow up to 3mm of movement - which will need to be made up using packers/ head gasket.
A lot depends on what you want to achieve and the port timings on the cylinder.
This explains it much better than I could.
https://www.mbscooters.co.uk/info/mb-*- ... s+190.html