This is a bit about 254G, love them.
Different jugs I've seen on them:
KS 073/1A and 1B, 11-86, thin ring piston, both year 87 week 17.
They changed from thin ring piston (1mm ring) to normal ring after serial number SG 7390091, SE 7400209.
KS 073/1A, 06-87, year 88 week 7
KS 073/2A, 02-89, year 89 week 37
KS 073/3B, 09-90, year 91 week 14
KS 073/1C, year 98 week 5
Mahle 45ZN7 W6, (placed on a 87, not the originale jug)
Mahle 45ZK12 W2, year 01 week 41
I think there is also Mahle without decomp valve.
Here is one lousy pictures off thin ring jug vs normal ring jug:
I'll shoot up some better pictures for the combustion chamber thin ring jug vs normal ring jug later:
More info from the 254 SG/XPG
There are three different G flywheel.
501 86 41 02, goes up to 88 model (non air injection system).
503 08 80 02, from 88 up to around 95 (same flywheel as 262 have)
503 52 94 02, from year 96 and newer.
There is two different oil pumps, same # number in IPL's but they are still different.
The old ones have 19mm hole for the crankshaft (bronse worm gear), newer ones have 22,5mm hole for the crankshaft (plastic worm gear). They are easy to modd so plastic worm oil gear can be used. On the backside of those who was made for plastic worm gear, one of the oil channels its marked with a H.
Picture of the difference:
Modded oil pumps:
254 IPL's (complete IPL's):
254 Workshop Manuals: