LCGB Forums

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.

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