The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: bsa-bill on 29.05. 2015 13:30

Title: rocker feed
Post by: bsa-bill on 29.05. 2015 13:30
anyone know what is the correct size of the copper pipe to the rockers, mine measures 4.7 ish mm but maybe it's an imperial size or just worn a bit.
Mine is a little short, requires a bit too much rubber pipe to connect it, I'll replace it with a longer piece or replace the rubber with some clear reinforced plastic, tho I prefer the polished copper
Title: Re: rocker feed
Post by: chaterlea25 on 29.05. 2015 14:09
Hi Bill,
its 3/16ths of an inch in old money  ;)

Title: Re: rocker feed
Post by: bsa-bill on 29.05. 2015 14:59
Cheers John I'll see whats on line or we have a good machine shop come supplier in Berwick (Jimmy Woods)
Title: Re: rocker feed
Post by: sparx on 29.05. 2015 21:13
I used 3/16" copper brake pipe. It's inexpensive and readily available. I drilled the old pipe out of the banjos and T piece then soldered the new in. If you give it a light coat of clear engine lacquer it stays nice and bright.
Title: Re: rocker feed
Post by: trevinoz on 30.05. 2015 01:13
You are better off silver soldering the pipes in place. Soft solder has a tendency to crack.
Title: Re: rocker feed
Post by: bsa-bill on 30.05. 2015 10:37
thanks Trev, I'll need to get some

still on topic - it's quite hard to blow through the feed pipe once it's connected to the rockers, it's down to the small hole in the feed bolts I guess air does get through with an airline but blow by mouth it requires a fair bit of puff, going to do a bit of measuring sometime today to see just where the small hole ends up, wondering if their blocked by the brass union onto the box.
Title: Re: rocker feed
Post by: bsa-bill on 30.05. 2015 20:04
No - nothing really wrong just the size of the hole, obviously works but I can see why people would think putting a bigger hole (Goldie type) would be a good move - NOT
Title: Re: rocker feed
Post by: bsa-bill on 06.06. 2015 21:26
right all fired up with some nice new copper pipe to make a new rocker feed using a spare one I have, I managed very easily to remove the old chopped off pipe from the oil tank union with a butane torch and camping gas, but the rocker end isn't  keen to melt (except for the end of my finger ).
Do I need to use propane, I'm thinking maybe it was brazed as I can tin the end of the new pipe with the camping gas (it a mix of butane and something else that escapes me at the mo)
Will need another torch i suppose

Title: Re: rocker feed
Post by: kiwipom on 06.06. 2015 21:48
Hi Bill, your butane torch should do the job you don't want too much heat or you will melt the brass connector. If ithe old copper tube doesn't come out easily it may be better to drill it out, good luck, cheers
Title: Re: rocker feed
Post by: bsa-bill on 06.06. 2015 21:56
OK cheers  kiwipom
Title: Re: rocker feed
Post by: duTch on 06.06. 2015 23:59

 Bill, you may be thinking of MAPP gas...?
"MAPP gas" is a trademarked name, belonging to The Linde Group, and previously belonging to the Dow Chemical Company, for a fuel gas based on a stabilized mixture of methylacetylene (propyne) and propadiene. The name comes from the original chemical composition, methylacetylene-propadiene propane.
Full story here; (

 Re the size of the pipe, I may be wrong, but'm thinking that in industry terms (plumbing,refrigeration, gas fitting), while 3/16" is the OD size,  it's referred to 1/8" as in I.D. size.....because when I went looking for some for mine and asked for 3/16, I think they came back with 1/4"...mostly only used in refrigeration these days... *????* feel free to tell me if I'm wrong..

Title: Re: rocker feed
Post by: terryg on 07.06. 2015 06:37
That sounds familiar re. pipe versus tube.

I believe pipe is specified by inner diameter while tubing is specified by outer diameter.

For example, 2 inch diameter pipe will take a 2 inch diameter ball. A 2 inch tube won't.

In either case the wall thickness must be separately specified.

I found this out when buying materials for my canister oil filter, which remains to be finished.
Title: Re: rocker feed
Post by: kiwipom on 07.06. 2015 07:33
Hi guys, you could be right Terry, I use copper pipe/tube in my work , it's ordered by (I. D.) or (O. D.) depending what is required, cheers
Title: Re: rocker feed
Post by: duTch on 07.06. 2015 08:37

 Usually called 'nominal bore' and also in irrigation which varies slightly from plumbing and/or drainage....
Title: Re: rocker feed
Post by: bsa-bill on 07.06. 2015 10:24
the Pipe was advertised  and marked (3/16 x 2g)  which it's OD is, it is around < 0.1 mm bigger then the original pipe on the rockers which won't be problematic if I'm drilling the old pipe out.
Gas is Butane Propane mix but if it melted the old pipe out of the tank union should be ok to solder the new pipe in.

Need to tidy up the shed before torching or if the wind dies down will be safer in the garage  ;)
Title: Re: rocker feed
Post by: bsa-bill on 10.06. 2015 17:53
Well all seemed to goto plan, torch if anything could get too hot right enough and had a tendency to blow the solder off the pipe, so once I'd sussed that and turned it down a good bit it was fine.
Drilled the old pipe out as suggested, brass being harder than the copper it was easy to feel when the drill had got to the brass, looked like the original had been brazed in which might explain why I found it difficult to melt out.
I have a pot of silver solder flux, used that on the pipe, the silver solder I got is quite fine, could have done with a thicker gauge I reckon.
Anyway anyone faced with renewing the pipe and not sure about it - go and give it a go I found it not too difficult, I also took the opportunity to reroute the pipe so less bends, probably where it's supposed to be  *smiley4*
Title: Re: rocker feed
Post by: KiwiGF on 17.06. 2015 11:53
Thanks for posting the pics and advice Bill  *smile*, I have done a similar but not so good job on my a10 and b31 (but using soft solder as I do not have the right torch to use silver solder) Fingers crossed it lasts! (4000 miles so far).

I was surprised how easy it was to get an oil tight joint but I guess there is very little pressure in these pipes.
Title: Re: rocker feed
Post by: Topdad on 17.06. 2015 13:23
Seems to have been an outbreak of rocker feed problems over the last few days .My bike went very incontinent last Wednesday ,waterproofed Sues boot by the time we got home . thought I'd just lost my touch with the rocker oil connections so was very surprised when I'd taken of one of the connecting bolts and half of the feed pipe fell onto the engine ( I use a pipe as supply ) a nice clean break . I tried to drill the broken side out as per bills method but didn't want to know very hard ,so then tried to melt it again no chance . Must be brazed ?? anyway the day was saved by a redundant original rocker feed that I'd had in the parts bin for over 40 yrs ! it just needed cleaning on the top feed connection ,used the drill to buzz it out and has I haven't any silver solder used normal stuff but got everything spotless and it went together wonderfully result a nice dry engine ,must have been cracked for some time, TWIT  *pull hair out* *red*. Bob