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Messages - Jim S

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Singles / Re: B31 ignition
« on: 31 May, 2022, 13:08:53 »
That could be gearbox oil also.


Singles / Re: BSA Gearbox ratios - BSA M33/B33 etc
« on: 22 March, 2022, 12:52:21 »
If you feel the engine is reving too high, compare your sprocket tooth count vs the manual. On my 1949 B33 I had a 48 tooth rear sprocket which I changed for a 44 tooth. This resulted in a 9% reduction in rpm. Now the bike cruises comfortably at 50mph and as an added bonus, the speedometer gives the correct reading.

Singles / Re: B33 Clutch and Gearbox work
« on: 05 November, 2021, 16:01:37 »
I would have a go at salvaging the original part that you have using a modified bolt.

Singles / Re: B33 Clutch and Gearbox work
« on: 04 November, 2021, 22:59:28 »
Hi Wayne
The parts book is a little confusing, but 66-3906 Is for a B31 and 66-3903 Is for B32, B33 B34 and Clubmans. I don't have any experience with running a B33 with 1 less set of clutch plates, but I would try to stay with the parts book configuration.

What is wrong with your old clutch center? If it is the photo on left, it looks good to me.

Singles / Re: BSA B33 Petrol Tank
« on: 30 October, 2021, 13:58:22 »
As Idie says, pay attention to the bottom of the tank. On my 1949 B33 plunger, there is an offset recess on the bottom to clear the engine valve rockers. On the tanks shown on eBay sites, the recess appears to go across the complete bottom of the tank, but there appears to be ridges extending down on each side of the tunnel.
Attached is a picture of the bottom of my tank and a picture from the bottom of an eBay tank. Has anyone installed a tank from eBay onto a plunger B33 with a tank bottom as configured in the photo?

Singles / Re: M21 rear sprocket change
« on: 17 October, 2021, 14:15:32 »
I went from 46 to 42 teeth on the rear sprocket of my B33. 42 teeth is the standard configuration. It made a huge difference. Engine revs are 10% lower. I can easily ride at 50 mph without worry about high engine revs.
On my bike, the sprocket and drum are also integral but it my be harder to find an M21 part. I bought mine from British Cycle Supply in Nova Scotia.

Singles / 1949 B33 Fuel Tank
« on: 17 September, 2021, 01:23:31 »
I have decided to not put any more effort and money into maintaining my current 1949 B33 fuel tank. It is full of lead and solder repairs that have developed small leaks that destroy the paint and create a fire hazard. I am looking to buy another tank.

When I look at the photos of the bottom of the tanks, there is a significant difference between my tank and the ones being sold from India. On my tank the bottom right side has a recess the full width and on the left side the recess is only half the width. On the Indian tanks, the recess is the full width on both sides.

Has anyone found a tank from India with an underside that looks like my tank? I am looking at tanks that have the screw-on emblems, which my tank has.

Does anyone have a positive experience with a particular supplier? I have seen in other forums that Pummy has a good feedback.

Singles / Re: Starting B33
« on: 12 August, 2021, 17:13:06 »
Maybe you are trying to start it with the ignition fully advanced? Some magneto configurations are advanced with a pull on the cable and some advanced by a push. To verify your configuration, remove the points cover and observe the rotation of the face cam when you actuate the advance/retard lever. Fully advanced is when the face cam is rotated fully counter clockwise.
I start my B33 about 1/2 advanced.
If you still have problems then you probably need to set the magneto timing. See service sheet 604.

Singles / Re: Burman gearbox
« on: 14 July, 2021, 13:47:19 »
Hi Wayne
There are lots of previous posts concerning the B31/33 gearbox including this one:
Do a search on b33 gearbox for more info.
I doubt that changing primary or gearbox oil type is going to help your problem, but most people put a lighter oil in the primary.

Twins / Re: 1954 A10 Clutch
« on: 12 July, 2021, 12:44:00 »
Hi Idle
I checked my notes from a previous clutch rebuild. After replacing a defective backplate, I had 0.019in run out on the backplate face, and by indexing I was able to get it down to 0.009in. You are measuring about 0.030in in your most recent build.

In your last post you say that you now have a functioning clutch but still have chainwheel wobble. Maybe the 0.030 backplate run out is contributing to that.

When adjusting the springs after the clutch is assembled, I disengage the clutch (tie wrap around the clutch hand lever), put a dial gauge on the outer face of the outside plate and use the kick start to rotate the clutch. I then adjust the springs to get minimum run out.

A dial gauge and magnetic base are a good investment imo. It was less than $50cdn on Amazon several years ago.

Anyway, if your clutch is working with no grinding when changing gears, that is great!

Singles / Re: B33 mystery Ratteling noise
« on: 25 June, 2021, 14:10:43 »
I had a similar problem with my B33 fuel tank for several years.

To address the problem at the front mount I have a rubber sleeve (rubber hose) over the fixing bolt and I drilled out the holes in the tank so the sleeve passes through. I also made rubber bushings and washers to eliminate any tank to frame metal contact. My fixing bolt is actually a stud threaded both ends and the rubber bushings are sandwiched between large washers on each side of the tank.

At the rear of the tank I basically used the parts book configuration, ensuring there is no metal to metal contact, however the rear bolts are only hand tight and lockwired so they don't fall out. I can slightly rock the tank by hand with this arrangement.

I also originally had a 46 tooth rear sprocket which I changed for a 42 tooth. The 42 tooth is standard. This results in a 9% reduction in engine speed. Maybe since the bike is reving lower it isn't coming close to the tank resonance?

I no longer have the anoying tank buzzing.

Twins / Re: metallic knocking sound
« on: 21 June, 2021, 14:47:08 »
The fuel tank can also make quite a noise if it starts to resonate and is not properly secured on firm rubber pads.

Twins / Re: Baffled with gearbox clutch
« on: 05 June, 2021, 12:56:21 »
Hi Mike
Maybe the studs on the clutch basket are contacting the inside of the cover?


Twins / Re: 1954 A10 Clutch
« on: 24 May, 2021, 01:39:27 »
Hi Restorer
I have found that clutch dragging and chainwheel wobble is caused by excessive run out on the face of the clutch backplate when installed.
With the correct clutch center installed on the gearbox shaft, install the backplate, bearing inner race, basket and nut (hand tight). With a dial gauge, measure the run out on the face of the backplate. I had one backplate giving in excess of 0.060in run out which was causing "drag" between the backplate and the chainwheel. In this case I replaced the backplate, but maybe it could have been salvaged by a machinist. Once you have a backplate with a reasonable run out ( 0.015in ?) You may improve it more by indexing the backplate on the clutch center to find the optimum position for minimum run out.

Concerning chainwheel corks, they can be made from wine corks and there are previous posts concerning how to make them. For sure they need to protrude beyond the faces of the chainwheel by about 0.060 in.


Singles / Re: B31 'snatching' in gear
« on: 18 May, 2021, 14:18:18 »
Hi Calum
Looks like you have found the problem. When you do the rebuild, make sure the shifter forks are not contacting the dogged wheel after any gear or neutral is selected. You may need to do several iterations of partial rebuild.
As for gear selector shaft end float, I rebuilt mine with 0.015in of end float and shifting is very good.

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