A quick glance at the despatch book shows that BSA started the 1939 season by continuing with the 1938 design of M22 engine, and up to 5/39 had produced about 350 of these engines with numbers prefixed KJM22.
Following on from that about 60 M22 engines with the redesigned crankcases; outrigger plate for the cams etc, were produced with engine number prefix KM22. The highest number I could see being KM22 192.
Some of the B series models also continued into 1939 with the earlier type crankcases, probably just a case of BSA using up what was already on the shelf first.

I can confirm the existence of engine KM22-190.

Kalle,
is the engine you mention the same as the one advertised on ebay ?
(I have some doubts about its side cover...)

Engine for sale on eBay appears to have engine number KM22.108.

Engine number showing on eBay engine appears to be KM22 108

Engine KM22 108 and the frame it was fitted in is shown in the despatch book. Probably best I don't give more details as I don't own it or have been asked to by it's owner.
Fair to say that almost all of the bikes fitted with KM22 engines were exported.
Easy to swap the timing cover for a later example...

And six or so KM22 engined bikes were snapped up by the War Office in September 1939, along with everything else they found lying around at BSA...

There are quite a few in the wartime Australian military ledgers.

Rob

13322 KJM19 4073 KJM22 423
31027 KJM19 4130 KJM22 487
31150 JM19 3265 KJM22 139
31245 JM19 132 KJM22 414
31265 JM19 4593 KJM22 404
31353 KJM19 3401 KJM22 134
31406 KJM19 3887 KJM22 256
31528 KJM19 3113 KJM22 189
31536 JM19 3374 KJM22 130
31558 KJM19 3901 KJM22 258
32083 KJM19 3900 KJM22 260
32135 KJM19 3878 KJM22 254
32142 KJM19 4115 KJM22 468
32218 KJM19 3966 KJM22 279
32236 JM19 3673 KJM22 135
32468 KJM19 3920 KJM22 257
32613 KJM19 3881 KJM22 231
32636 KJM19 2905 KJM22 235
33496 KJM19 3533 KJM22 114
33547 KJM19 348 KJM22 111
33638 JM19 3151 KJM22 118
33673 JM19 3542 KJM22 164
33703 JM19 3352 KJM22 110
33718 KJM19 3924 KJM22 362
33849 JM19 3389 KJM22 116
34690 JM19 3301 KJM22 113
35130 ? ? KJM22 210
35277 ? ? KJM22 419
35355 HM19 4154 KJM22 410
35372 HM19 4277 KJM22 417
35420 JM19 4093 KJM22 405
35524 KJM19 4010 KJM22 353
35526 JM19 3090 KJM22 174
35544 JM19 3976 KJM22 328
35545 JM19 2179 KJM22 178
35548 JM19 3329 KJM22 176
35561 JM19 3295 KJM22 173
35601 JM19 5348 KJM22 177
35608 KJM19 3969 KJM22 314
35631 KJM19 3975 KJM22 336
35660 JM19 3158 KJM22 163
35665 KJM19 4112 KJM22 434
35666 KJM19 3941 KJM22 280
35676 KJM19 3919 KJM22 2263
35681 JM19 3292 KJM22 214
35749 KJM19 4006 KJM22 376
35798 KJM19 3852 KJM22 223
35799 KJM19 3638 KJM22 203
35837 KJM19 3995 KJM22 2361
35854 KJM19 6968 KJM22 339
36010 ? ? KJM22 329
35061 ? ? KJM22 264
36110 ? ? KJM22 435
36157 ? ? KJM22 9181
36159 ? ? KJM22 387
36320 ? ? KJM22 283
86002 JM19 3435 KJM22 165

31809 KM20 4756 KM22 135
32073 KM20 4731 KM22 739
32176 KM20 4757 KM22 168
32216 KM20 4756 KM22 125
32444 KM20 4765 KM22 163
33057 KM19 4257 KM22 412
33495 KM20 4732 KM22 167
33946 KM20 4773 KM22 141
34811 ? ? KM22 140
34838 ? ? KM22 144
35706 HM19 1261 KM22 315
35891 ? ? KM22 463
35935 ? ? KM22 474
35987 ? ? KM22 178

email (option): robmiller11(a)yahoo.co.uk

Looks like they were putting all sorts of frames and engines together!!

Hi
Engine KM22 190 is in Estonia and was in WM20 frame when found.