Differences in cg125 m1 engine vs pre 2001

[cairnsie13]

I bought a non running cg which came with spare engine. Original engine had no conrod or piston in. I bought this as a project and a winter bike.

I swapped the engines and and noticed the top end was getting no oil. Previous owners had gasket sealed up the oil ways. I sorted the issue, reassembled the engine and ran it over winter. I only put about 200-300 miles on it. Its been smokey, burning oil, hunting on idle, low compression and generally not running well despite swapping carbs checking settings etc.

Ive took the engine apart to put new rings in etc and realised they put a pre 2001 barrel, piston and head on the bike.

This means part of the oil ways have not been connected.

What is the other oil way feeding on the newer type engine as its done at least 300mile with no oil feed.

Is there anyway of making a pre 2001 barrel fit or can i run a newer barrel with old style head and piston.

I was originally going to put a 150cc overbore on and this is when i realised there was a difference between the new and old engines.

Any help appreciated.