Author Topic: B31 head onto B33 Barrel  (Read 378 times)

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sidewaysid

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B31 head onto B33 Barrel
« on: 20 February, 2018, 17:11:24 »
Hi

I'm sure Andy Ingham can put me straight. I have a B33 barrel and piston but my B31 head won't quite fit, would it be fine to turn a little out of the diameter (it's only about 2 mm) is this common practice ?

sidewaysid

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Re: B31 head onto B33 Barrel
« Reply #1 on: 20 February, 2018, 21:03:10 »
Sorry I mean Andy Higham, he seems to know a thing or two on the singles, I'm going to see if i can do that Suzuki clutch conversion like he has done.

ANDY HIGHAM

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Re: B31 head onto B33 Barrel
« Reply #2 on: 21 February, 2018, 13:33:47 »
I would say even if it was possible it would be undesirable. The compression ratio would be high and the valve sizes smaller than the B33

sidewaysid

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Re: B31 head onto B33 Barrel
« Reply #3 on: 22 February, 2018, 20:20:10 »
Andy you have put me right off putting a B33 barrel and piston onto my B31 engine, I am in the early stages of building my bike, I keep saying to myself it isn't going to be a concours winning example ( I have built these before, and have the trophies) it is going to be an old thumper to ride around the lanes, I did have a B31 swing arm model a long time ago, and it was a bit gutless, so i am thinking bump up the capacity (oh and bye the way I am not trying to emulate a Gold star, no interest) But with what you said Andy Higham, I have decided to go down the route of a T140 piston and overbore the B31 cylinder, I have 2 cylinders a small diameter fin and the large diameter fin, I'm going to use the large fin, it looks better suited to the head, I would gladly appreciate any help and constructive comments please, I am not a died in the wool BSA man, but I have always thought them solid as a rock since I had one to transport me to College in 1969, it was a C11G, what a lovely bike.
Andy I have purchased a Suzuki GS850 clutch, and would appreciate it if you could let me have some more detail of how you grafted it all together, I have a BSA centre hub, and I'm sure i have the clutch basket from an A10 or even a Triumph.

Please help

ANDY HIGHAM

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Re: B31 head onto B33 Barrel
« Reply #4 on: 23 February, 2018, 12:39:41 »
Follow this link and there is a full write up of the modifications I made to my B31
http://www.britbike.com/forums/ubbthreads.php/topics/640945/b31-clubman#Post640945