Author Topic: Starting B33  (Read 406 times)

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David Johnson

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Starting B33
« on: 12 August, 2021, 15:41:12 »
Hi.
Just bought a B33, 1955, but I think it may be earlier as it's a plunger. Has stood for 4 years. Several hours and people and googling etc and a it won't come near running. A very weird thing is happening...when it fires (which it only does occasionally) the rotor arm rotates suddenly in the opposite direction, not just momentarily but for a second or two until the turning-over stops! Does this mean the engine is trying to run backwards? Could the timing, for example , be 180 degrees out? Please, any ideas so welcome. Thanks.

Jim S

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Re: Starting B33
« Reply #1 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.

David Johnson

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Re: Starting B33
« Reply #2 on: 12 August, 2021, 17:40:20 »
Thank you very much Jim. That's right; as far as we could glean, the setting requires just a slight Retard, which we took as full advance and then slight Retard.

This is also the only position it seems to fire in at all. But will now retry, and confirm the lever orientation IAW with your advice. It's a gorgeous bike in all other respects, fully restored, so well worth all efforts. Thanks again
David

Pete C

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Re: Starting B33
« Reply #3 on: 13 August, 2021, 08:24:29 »
I too would suggest checking / setting the timing so that you are sure that is not an issue. Then for starting I go for about half way retarded to start but every bike is different in how much retard is needed. If it still will not start and you have good compression then the carb may be dirty, having stood for a few years.

idie

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Re: Starting B33
« Reply #4 on: 13 August, 2021, 09:08:35 »
Make sure that it hasn't wet sumped. The oil drag on the flywheel will stop you swinging the engine over fast enough to start. I have problems with mine unless I drain the surplus oil off first.

David Johnson

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Re: Starting B33
« Reply #5 on: 13 August, 2021, 10:58:40 »
Thank you both very much. We are with it now, and will do those things later today or tomorrow.
Thank you.

Rog1

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Re: Starting B33
« Reply #6 on: 13 August, 2021, 13:14:33 »
Is it possible that the previous owner, knowing the bike wasn't going to be used, poured several ounces of oil into the combustion chamber to protect the bore and rings? The oil wouldn't compress so the piston can't quite get past top dead centre; the air and fuel mixture it has just compressed that's on top of the oil then expands and pushes the engine backwards. When turning the engine over in preparation to start, you'd use the decompressor lever so wouldn't notice.

It seems unlikely but it's easy to check.

David Johnson

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Re: Starting B33
« Reply #7 on: 14 August, 2021, 11:59:09 »
Thank you Rog, that certainly sounds feasible, and would explain all the symptoms. Makes me wonder if there's another way that could have happened, although the plug doesn't seem excessively oily. We didn't get on it yesterday as planned, so will investigate asap. Thanks again.

Rog1

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Re: Starting B33
« Reply #8 on: 23 August, 2021, 18:25:36 »
Hi, any progress?