Author Topic: Exhaust valve lifter  (Read 904 times)

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DADSBIKE

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Exhaust valve lifter
« on: 15 February, 2017, 09:24:48 »
Hi Chaps,
does anyone have a drawing or close-up photo of the exhaust valve lifter (decompression) on the engine of an S28 BSA (1928 493cc single)?
Mine just has a plate bolted between the tappets, where 'something' has broken off.

Thanks

john

JulianS

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Re: Exhaust valve lifter
« Reply #1 on: 15 February, 2017, 19:57:49 »
John

Could you post a photo of the broken bit?

JulianS

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Re: Exhaust valve lifter
« Reply #2 on: 15 February, 2017, 20:57:02 »
Does this look photo look about right?

I think the part is the "tappet guide plate with bush" part 24 420 which was a common part for the 1926/27/28/29/30 engines.

I think its the 1926 engine in the photo which comes from Pitmans Book of BSA by Waysider 1930 edition.

The second photo is from the 1926 parts book.

DADSBIKE

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Re: Exhaust valve lifter
« Reply #3 on: 18 February, 2017, 09:11:07 »
Many thanks Julian,
 that's exactly the parts I need. I have made another plate but have yet to make the spindle, with some sort of cam at the tappet end. I was wondering about using the lifter spindle only from the M21......unless someone has the correct bit?!

Where do I find the 1926 parts book?

john

DADSBIKE

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Re: Exhaust valve lifter
« Reply #4 on: 18 February, 2017, 10:21:09 »
Just found and ordered the parts book for 1928 from Draganfly.....

JulianS

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Re: Exhaust valve lifter
« Reply #5 on: 18 February, 2017, 11:33:07 »
Most parts books can be downloaded by BSAOC members in the Club website members area. Unfortunately not the 1928 issue.

The 1928 issue is a short issue of just about 100 pages. It needs to be used in conjunction with the 1927 issue which has over 300 pages. Some of the parts for your bike may will not show in the 1928 issue.

I have added the front page of 1928 so you can see what BSA said.

Second photo shows the valve lifter cam and lever from parts book. Your parts are 27 423 and 24 79.

DADSBIKE

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Re: Exhaust valve lifter
« Reply #6 on: 18 February, 2017, 11:57:52 »
Thanks again Julian, pity there are no dimensions shown, but I suppose it's not 'rocket science' to make something up.


DADSBIKE

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Re: Exhaust valve lifter
« Reply #8 on: 18 February, 2017, 19:27:21 »
Yes thanks ....I just got it!  it looks to be the correct part this time, as I got one (splined, longer and unuseable) from the same seller last week.
Just need to make the shaft and bushing, but the drawings helped a lot.  :)