cylinder or barrel

[Zina Vandevelde]

Did BSA make a B40 with a square aluminum cylinder or only a cast iron round one?

[john.k]

B40 was a 350 with an iron barrel and were commonly used as army bikes.......B44 had a alloy barrel ,and was a 440.....IIRC.

[Zina Vandevelde]

thanks, so I assume that the 440 you mention is actually a 441 like a  Victor. So there is no alluminum cylinder for the 350 cc . Dick

[john.k]

In the far distant past i bought a BSA Victor. 441 Scrambler.....the big end knocked out in about 5 minutes.I bodged it,and sold the bike.All I know............As for the 350s,I used to buy them at the army sales.......double pallet with 8 bikes strapped on for $300-$400.... about early 80 s,I reckon....B40GA ,they called em.....The army found them to be rubbish,and replaced them with Suzuki 400 twins,all painted green......They used to sell for about $300 for 8 strapped to a double pallet.

[Zina Vandevelde]

thanks John

[Zina Vandevelde]

I have a 1969 250 Triumph. It needs a rebuild so I want to put an 850 Norton sleeve in it and use the 750 Triumph zipkit in it. It has the same pin diameter as the Triumph and is almost the same weight which I think will come out to about 310 cc. It should have similar compression ration as the Triumph, about 10-1. Do you think this is a bad idea? thanks, Dick

[TGR90B]

That question reminds me of the problems page in a 1960s edition of Motorcycle Mechanics. If it hasn't been done before you can't expect a definitive answer. I don't think those engines were that robust; from what I've read.

[john.k]

I think the 69 will have a 500 twin rod and plain bearing and a one piece crank...from memory....i also think that the plain bearing setup cured the bigend failures that were common ......but I dont know.......my memory of those days is getting sketchy......You are probably best to contact someone like SRM.who are still in business.

[Rex]

Had a 1961 B40, one of the first 1000 made according to the engine number. It had the round iron barrel and was as reliable as anyone could wish for. Simple and strong, and as long as the rider didn't think it was a motorway cruiser it would last and last.
Never into trials but as I recall the B40 was sought-after by those who like to get cold and wet, though one of the biggest drawbacks was the heavy iron barrel so I guess there never was an alloy pot for the 350.

[mini-me]

Engines noted for their ability to self destruct;  Grass track lads used to tune the balls off them when they'd go really well before they went bang.

I sold them new, never known so many Guarantee claims. Crap bikes, crap engines, crap all round.

Personally I would not give one room in a skip.

 WD B40 made a nice soft engine for a trials bike.

The there was the 500cc version of the 250, B50, sold those new as well, what a pile of crap, if you could get them started. Did well on the tracks for a bit though.

[Zina Vandevelde]

John K you are right. It is a one piece crank with alluminum rod. What does SRM stand for?  This bike was raced in the Baha and piston seized. I am not planning to race with it though, I just want a little more torque. Dick

[john.k]

Ah..you are in the US of A.......Mexifornia?....BSA s were big there once.....not so much now,I suppose.

[TGR90B]

A 60 cc increase in capacity should give you more torque. Not sure about the 10-1 C/R though.