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#586815 - 02/22/15 7:02 am Twin port BSA Sloper parts needed  
Joined: Oct 2001
Posts: 1,059
Shane in Oz Online content
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Shane in Oz  Online Content
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Sydney, Oz
I've been looking for a new piston and valves for a 1931 twin port o.h.v. Sloper (S31-9) without a lot of success.

I'm reasonably certain that JP pistons can supply the piston and rings (apparently it's a 2 ring piston, 24-676), but the valves are proving rather elusive. According to the parts book, the inlet and exhaust are both 24-490.

Can anybody suggest a source for the piston and / or valves?
How about alternative valves which could be modified for the job? B50 inlet valves are very close to the dimensions but would the steel be suitable? I suspect that late 1960s inlet valves are more than capable of working as 1920s exhaust valves, but it's better to ask than just charge in.
How about Black Diamond B50 inlet valves?
The valve guides are totally shot, so going to a 5/16" stem diameter isn't a problem.
How about alternative pistons? I've been told that there's a car (Austin, I think) piston which is very similar, but surely the eccentricity would be different for a water cooled motor?

While I'm chasing hen's teeth, does anybody have a rocker box that hasn't had the mounting lugs broken off?

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#586821 - 02/22/15 8:03 am Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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rocketgoldie Online content
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rocketgoldie  Online Content
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North Wales Uk
Hi try mikesclassics@bigpond.com he is in QLD his phonr no 0061738040055 tell him val told you.

#586907 - 02/22/15 3:41 pm Re: Twin port BSA Sloper parts needed [Re: rocketgoldie]  
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Shane in Oz Online content
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Shane in Oz  Online Content
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Thanks Val. I don't think Mike has anything pre-War, but I'll ask him.

#587001 - 02/23/15 1:16 am Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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Gordo in Comox Offline
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Comox BC Canada
Did you try Draganfly in the UK? They used to have a lot of NOS BSA stock.

Gordo


Without frequent roadside repairs there is no fun in riding!
#587050 - 02/23/15 12:38 pm Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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Alex Offline
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Seattle
With this sort of thing, if the parts cannot be found, I usually go for a "find something close and adapt" approach. For the valves I am in a similar situation on my M23 and my plan is to cut down M20 valves. Since they are sidevalves, the stems are very long letting you adjust the length and turn in any feature needed for the keepers. Draganfly can supply stainless M20 valves. The head diameter of the inlet looks to be close enough to your sloper valves (1.759 vs. 1.750 in). The stem diameter is .025" smaller on the M20 valves so guides would either have to be K-lined or new guides made.

For the piston, I would try to find a more modern substitute. For my rudge, I've found an HC goldie piston to substitute and those have oil rings (oil rings are nice to have). Do you have an existing or old piston to measure bore, wrist pin height and wrist pin diameter on?


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#587139 - 02/24/15 5:50 am Re: Twin port BSA Sloper parts needed [Re: Alex]  
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Shane in Oz Online content
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Shane in Oz  Online Content
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Thanks for the suggestions, gents.

Alex, the original pistons were 2 ring, so I'll see how well the JP version work. That should give me a starting point for finding a 3 ring piston if the 2 ring is too smoky.
I wouldn't trust the 3 ring piston currently fitted as any sort of guide to what it should be.

The best match I've found for the valves so far is a Ford Boss exhaust valve, which has an 11/32" stem instead of the original 3/8", so the collets might be "interesting". To be fair, the guides were absolutely stuffed and need to be replaced. The head diameter is 1.76", which is as near to 1.559 as to make no difference. They will obviously need to be shortened and have new collet grooves machined.
The valves in there at the moment look to be roughly modified car or truck valves; the exhaust valve is burnt and the stems are extremely worn.

#587174 - 02/24/15 1:50 pm Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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Rickman Offline
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Ohio
Originally Posted By Shane in Oz
The head diameter is 1.76", which is as near to 1.559 as to make no difference. They will obviously need to be shortened and have new collet grooves machined.


Are you saying this tongue-in-cheek???

Or is this a serious remark?

.201" NOT serious on the diameter of a valve head??? One fifth of an inch???

#587183 - 02/24/15 3:31 pm Re: Twin port BSA Sloper parts needed [Re: Rickman]  
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Shane in Oz Online content
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Shane in Oz  Online Content
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Sydney, Oz
Originally Posted By Rickman
Originally Posted By Shane in Oz
The head diameter is 1.76", which is as near to 1.559 as to make no difference. They will obviously need to be shortened and have new collet grooves machined.


Are you saying this tongue-in-cheek???

Or is this a serious remark?

.201" NOT serious on the diameter of a valve head??? One fifth of an inch???


Typo frown

The Sloper valves are 1.759" head diameter, with a 3/8" diameter stem.

#587186 - 02/24/15 4:19 pm Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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Alex Offline
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Seattle
I've made replacement guides out of blanks from Goodson:

http://www.goodson.com/Universal-Repair-Valve-Guides/

...with good results FWIW.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#587200 - 02/24/15 6:03 pm Re: Twin port BSA Sloper parts needed [Re: Alex]  
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Rickman Offline
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Rickman  Offline
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Ohio
Now, this was several, no, many years ago, but, I found a business in the back pages of Cycle news, a newspaper type publication, who made me a set of SS valves, swirl polished, slightly oversized from a sample I sent them [ .050" ].

Sorry, I cannot remember their biz name...

#587201 - 02/24/15 6:09 pm Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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downhere Offline
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Australia
If you were in Melbourne, Headworks would sort it out for you. He's in the Murrumbeena area.

#587223 - 02/24/15 8:12 pm Re: Twin port BSA Sloper parts needed [Re: downhere]  
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Shane in Oz Online content
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Shane in Oz  Online Content
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Sydney, Oz
Originally Posted By downhere
If you were in Melbourne, Headworks would sort it out for you. He's in the Murrumbeena area.


Thanks. I just spoke to Basil - he doesn't seem daunted by it.

I owe you a beer or 2 at the All British.

Last edited by Shane in Oz; 02/24/15 8:22 pm. Reason: updated after speaking to Headworks
#643379 - 03/08/16 11:11 am Re: Twin port BSA Sloper parts needed [Re: Shane in Oz]  
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calvin Offline
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calvin  Offline
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Chigwell, Essex, UK
Hi Shane, this is a shot in the dark as your post was years ago but I am in a similar situation requiring new valves for my 1930 Sloper 500ohv. Did you ever find a suitable alternative valve?
Thanks
Calvin

#667408 - 09/12/16 6:25 pm Re: Twin port BSA Sloper parts needed [Re: calvin]  
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Shane in Oz Online content
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Shane in Oz  Online Content
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Sydney, Oz
Originally Posted By calvin
Hi Shane, this is a shot in the dark as your post was years ago but I am in a similar situation requiring new valves for my 1930 Sloper 500ohv. Did you ever find a suitable alternative valve?
Thanks
Calvin

I clean missed this earlier, sorry.

My original head was apparently unsalvageable, but I managed to dig up a less worse one and send it down to Basil. He's working on it now, so I'll update everybody when I get it back.
I think he said some time ago that he modifies Chev valves.


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