It looks like I am buying a B33 this weekend. I once owned an A10, which I dearly loved. Any advice concerning the B33? Weaknesses, things to look for that may indicate imminent failure? Safe top speed?
Thanks in advance to all who respond.
Hate is a poison which one consumes hoping for another to die.
Hi Stubbicatt, I've run a '58 Alternator Model B31 since 1974 and found them to be generally over-engineered and bulletproof. The B33 is a better bike for distance cruising but engine parts are becoming scarce compared to the B31's.
The only weaknesses to speak of are the magneto's (if it hasn't had a recent overhaul) and distributors on the later models (1958-on). A mag rewind with new condenser will sort that problem but if it is an Alternator Model with a distributor check that there is no play by trying to move the contact points housing. If there is movement it is normally caused by wear in the main body of the distributor and/or the long shaft that goes all the way through from the drive pinion to the contact points. Replacements of both the shafts and the bodies are few and far between but they do turn up on eBay from time to time.
The B33 was good for about 84mph when new so I reckon that 60/65mph would be an adequate cruising speed. I cruise my B31 at that speed but I have played about with the engine somewhat.
Good luck with it and let us know how you get on??
I've got a 56 engine B33 in a 53 rigid frame. Never have come close to 84 mph, but it will hold 60 pretty easy on the level. I always wonder how well I really have it running, its a different breed of cat from my other bikes. I do like it a lot and wouldn't mind dragging another one home someday.
If my shagged out Smiths speedo is to be believed, 65mph is the sweet spot for my 54 B33 in a swing arm frame with a mono bloc carb. Any higher than that mine gets it gets a bit vibracious (if there is such a word)
It's got the mag/dyno set up but no issues yet in that dept but it is something to consider buying an un known machine as Beezageeza mentioned.
The engine itself is bullet proof with lots of low end torque
I have no experience with the plunger frame set up but have read that it's a bit lighter in over all weight than the swing arm set up
I tend to wear a shit eating grin when I ride my B33
well i restored one that must have been well used or abused.it cost me the national debt to complete in parts alone. i liked it when it was done. it also was a 54 swing arm. id look for a alternator model mag dynos dont impress me.the platform wear they are talking about is the two milled slots in the crankcase that accept the dowels pressed into the dyno base. the resulting point contact and vibration do the rest in notching those grooves.this screws up drive gear alignment. mine also had cracks adjacent to the main bearing bore in the case. fairly common i was told.so are beat out bores too.the next thing was the oil pump drive bore isnt bushed and the thrust wears out the bore. run a gold star big end.be aware that zb and bb engines have different length rods and different deck height pistons. this further complicates sourcing very scarce (in the u,s.)parts. draganfly and and the fellas in new zealand for spares but British Only sold me a new but rusty barrel. its a lot emails and phone calls.tin as like all the rest of the line is very scarce.this isnt a cheap bike to do if it has the guts run out of it i know. and you wont know until you buy and take it apart the fairness of the sale. like i say i liked it but id think twice before i did another. just my two cents worth
I used to run a B33 before upgarding to Goldstar, the B33 is very solid, but not fast in standard trim, the B33 is very tuneable using various Goldi bits, like cams, rods, pistons,etc. Stsndsrd a B33 will do 80-85 mph when in good condition, a tuned B33 can do the ton. Weak points is the magdyno (and expensive to fix) if its not overhauled recentely,
You are asking about plunger, personally I rate the svinging arm first, the ridgid no two and last the plunger.
There is no damping and the plunger suspension and with smallest amount of wear the rear wheel are all over the place...
Per Goldi Clubmans Goldi Scrambler Rob North R3 OIF A65
Hm. Perhaps I should re-think this transaction. If I understand correctly, parts are difficult to find and expensive. There are design or material defects at critical places, such as the oil pump, the mating of the magdyno and crank cases, and the crank case main bores.
The speedometer shows 75000 miles on it, which if correct, suggest to me that either the engine has been through overhaul or it will be in need of the same soon. The plunger rear end is squirrely if even slightly worn. Top speed is limited by vibrations above 60 mph, so all told it isn't a good choice?
If I test ride this thing, what am I looking for re: the plunger suspension? Is it something I can push/pull the rear wheel to determine wear, or is it something one has to ride, tilt into a corner, and be surprised?
I understand the oil pumps are similar to that of the A10 I owned, which wet sumped enough to be annoying. Is there anything that can be done re: the oil pump to improve its performance and its resistance to wet sumping?
I reckon if it comes time to round out the egg shaped dowel holes from the magdyno, I'll reweld and bush that location. Perhaps it will make a difference, and if possible, bush the oil pump drive. As far as out of round main bores... Groan.
Last edited by stubbicatt; 10/15/138:35 am.
Hate is a poison which one consumes hoping for another to die.
Stubbicatt....you seem to have taken a fairly pessimistic view of what was one of BSAs most popular bikes designed to handle sensible owners for a vast length of time ...of course there are things which could have been improved but generally speaking those tend to come to light if you neglect maintenance and ring the ***k out of it every time you take it out.
Start "upgrading" bits and pieces is where you run into big bucks. Get it running right and you will have years of fun with it.
Ive got a plunger set up on an A10 and they are very nice to ride and THEY LOOK GOOD.
For my money the B33 plunger is a dam fine old bike and one of the most reliable.
the gearboxes are bomb proof it should have the M series box (the one with the screw on plug over the clutch pivot) That gearbox has been known to have a problem 2nd ==> 3rd but if its working fine NOW it will probably only last another 60 years
it all depends on the condition its in when you get it . any way you can post a few pics or give some more info on its current state?
Oh yeah ...they handle very well on the open road and are a pleasure to "manoeuvre" through traffic.
I followed a dude on one on some twisty back roads and that guy was flicking that thing about with full confidence that it would go where he placed it! . I seriously struggled to keep him in sight on the A65 even with some straights to catch sight of him , at least ( I dint know where we were going!) admittedly that guy was a racer and sure knew the roads but the point is the handing!!!!!!!! PS he was running std set up.
Last edited by Ignoramus; 10/15/135:17 pm.
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