AJS G2 - Engine Design Changes; 250 c.c. Model

TABLE OF CHAINS
Chain Sizes (Heavyweight Model)
Front chain
Rear chain
Magneto chain
Dyno chain
½" + .305"
s" + .380"
a" + .225"
a" + .225"
1957 Models
Front
Rear
Magneto
Dyno
350 c.c
67 links
98 „
46 „
50 „
350 c.c
Trials
66 links
97 „
46 „
50 „
500 c.c
68 links
98 „
46 „
50 „
500 c.c
Scrambler
67 links
97 „
46 „
50 „
1958 Models
Front
Rear
Magneto
Dyno
350 c,c
67 links
98 „
46 „
50 „
350 c.c
Trials
66 links
97 „
46 „
50 „
500 c.c
68 links
98 „
46 „
50 „
500 c.c
Scrambler
67 links
97 „
46 „
50 „
1959 Models
Front
Rear
Magneto
350 c.c
67 links
98 „
350 c.c
Trials
66 links
94 „
46 „
500 c.c
68 links
98 „
500 c.c
Scrambler
67 links
97 „
46 „
1960-1962 Models
Front
Rear
Magneto
350 c.c
67 links
98 „
350 c.c
Trials
66 links
94 „
46 „
500 c.c
69 links
98 „
500 c.c
Scrambler
67 links
98 „
ENGINE DESIGN CHANGES
250 c.c. Model
The GSR model was first introduced in 1962 starting with engine
number 12128. The alterations made to the engine were;
(1) Steel flywheel—to replace iron type,
(2) Large diameter crank pin—to allow use of the high compression
piston.
(3) Larger inlet valve similar to the valve used on the lightweight 350
engine to improve volumetric efficiency of the engine.
(4) Engines with number from 12828 have a modified oiling system with
the stroke of the pump altered to increase oil circulation. Earlier
engines cannot be modified as a new crank case is required. With
this system oil was fed to the cam followers for better lubrication.
(5) Compression ratio increased from 8 to 1 to 9.5 to 1 made possible
by the introduction of steel flywheels and the large crank pin for
the big end.
Engine noises. A light rattle audible when running without a load, and
disappearing when the engine is under load, is due to slight movement in
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