Hi all, been offered a 39 m24 engine for my 39 m21, would the m21 gearbox be ok to use,any thoughts. curt

Hi Curt,

If you don't take that engine let me know. I would love to find an M24 engine.

Henk

email (option): ahum@quicknet.nl

henk, i will be having the engine to good to miss, but he also has some more m24 parts and some empire engines complete, cant get it for a couple of weeks, so will let you know whats for sale. curt

Only the 1938 M24 gearbox was Elekron Magnesium alloy casing, the 1939 model was just normal material as Civvy M21
both years standard ratio
1 st 14.3:1
2 nd 9.9:1
3 rd 6.3:1
4 th 4.8:1

But for 1939 you could chose an optional Close ratio box
1 st 11.85:1
2 nd 8.3:1
3 rd 5.25:1
4 th 4.8:1

in other words, a 1939 M21 would be perfectly acceptable obviously looks best if it has the correct tapering clutch arm rather than a WM20 one often seen & i think it would have a locating grove to hold the rubber cover ( covers on eBay for a fiver).

My M24 engine is a 38 & its very good fun, i was advised to forget the high compression 12.5:1 & standard compression 7.75:1 M24 pistons & run it on a M23 piston (not sure exact comp ratio) & good advise that was, its very happy on modern fuel & runs sweet with surprising performance.

thanks for that, my first job is to get the engine home, its not for sale on any web site, so have a good chance. cheers curt

Well hope you get it, if he wants more just pay more, heads & barrels alone are extremely sort after. particularly as both years are different heads & barrels.
good luck.

Hi Curt. Take a look please if he has m22 or m23 crankcases and barrel for sale both HM and JM are ok. Thanks.

Kalle

email (option): kalle.tikas@gmail.com

Curt if there are cylinderheads single or two ports and rockerboxes for sale let me know Gr. Theo Schipper

email (option): oldbikes@kpnmail.nl

can i join the queue for any km23 parts please ????

email (option): chris.astinbarker@btinternet.com

Hi curt,Iam after any M23 engine internals,timing gears,crankshaft,pushrod tunnel rockershafts,etc.Thanks Mick W .

email (option): michael.westlake@hotmail.co.uk

Hi Curt,

I am still looking for a JM22 (1938) M22 single port cylinder head with two holes per valve casting to attch the rocker box (later types have 3 holes).

Best regards,
Leon

email (option): leonhop3@planet.nl

hi all. will ask about other engines parts, he has just send me some pics of this m24 engine, it will need rebuilding and some alloy work,comes with a carb no mag, new piston and a gasket set. he's looking for 3k for it, which ok is a lot of money but, they dont come along every day, i did try and buy one last year on ebay, which went for 4600, which was not running, so could be in a deeper hole, i have checked on the m24 site, this engine is not listed on there.. heres some pics..please let me know what you think, warts and all.. cheers curt..

http://s305.photobucket.com/user/sevenup_photos/media/bsa%20m24%20goldstar%20engine/gs25_zpsa71d7ccc.png.html?sort=3&o=0

Curt, I can look up when and where J and KM24 engines went to if you let me know the engine number.

email (option): 79x100@gmail.com

will send you an email. cheers curt.

just interested to know if anyone has put the m24 engine in the m21 frame, and what issues they had...curt

this is a reply back from him with other parts for sale....

" parts for sale, engine in bits # KB 26 771, engine # KB 24 1191,
engine # KB 461, engine # KB 21 696 only bottom half, ZB 31 23823 with ally
ZB 350 head and barrel, ZB 31 frame. some to think about."

curt

It'll fit, but you will need a different tank with cutaway underneath.

this the underside of my tank, it has the cutaway i think, or is it more than this..curt

http://s305.photobucket.com/user/sevenup_photos/media/BSA%20M21%201939/bsam21parts2004.jpg.html?sort=3&o=37#/user/sevenup_photos/media/BSA%20M21%201939/bsam21parts2004.jpg.html?sort=3&o=37&_suid=1373751306250006500050452778572

Your tank might be OK for clearance i have a feeling that BSA made all the post war "M" tanks with clearance for OHV engines so may well be OK can't say definitely but try it first, the highest points are 2 bolts & the decompressor cable which are where the tunnel is anyway.
pics look fine nothing horrible .. typical rocker cover damage it must be where people don't slacken tappets off before removal etc because guess what.. mine have both also been welded there.
Piston needs identification (from number inside) as it looks low comp but prob makes it a good choice.
crankcases, cams, head, barrel all look correct for a KM24 (39)
Price is not greedy at all.

Exhaust downpipe shape is different to 38 also if he has one there, its flat at the front.
People wrongly point at the fins either side of the pushrod tunnel on mine assuming they are broken or modified.
All the "M" engines & frames widened 1939 onward so your engine will fit your M21 frame but you would actually have more trouble putting it in a 38 M24 frame.

cheers Cycle Fred, all info is a help.all being well should have by next week..curt

Well i really like riding my 1938 engined bike .... its on a 45" straight through pipe so you can hear all the bangs
: D
Still amused that they produced an engine that you have to guess the tappet clearances on.
But even considering they had to add those two bolts either side of the pushrod tunnel as an afterthought i really do think the head & particularly the barrel on these engines are nothing short of a work of art.

these engines along with some m20 frames will be for sale at stanford hall this coming sunday. stall F14 ask for eric... curt

Fred...At least you don't have to guess the valve guide clearances like the 16H... ...Ian

email (option): ian@wright52.plus.com