Author Topic: BROKEN BARREL FIN REPAIR  (Read 2983 times)

Offline brissy_bsa

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BROKEN BARREL FIN REPAIR
« on: 19.01. 2007 05:30 »
Hi all,
Just took the A10 barrel to be refurbished (part of the top fin of the barrel is missing). The guy at the bike shop said he wouldnt weld it, as by doing so, the barrel could be damaged. He suggested that I grind back the remaining edges and then by laying some cardboard down on top of the next fin (to create the gap), I could use automotive putty and build a new fin, sanding and grinding the edges to match the shape. In other words a cosmetic repair. I am seeking your thoughts on this. Seems a bit shronky to me !
Cheers Ian

Offline fido

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Re: BROKEN BARREL FIN REPAIR
« Reply #1 on: 19.01. 2007 08:24 »
I suggest you take it elsewhere. Fins can be welded using cast iron welding rods or they are sometimes brazed. The whole casting would need to be preheated as intense localised heat could indeed cause damage to a cold barrel. You need to find someone familiar with restoration work.

Offline LJ.

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Re: BROKEN BARREL FIN REPAIR
« Reply #2 on: 19.01. 2007 09:17 »

I have had mine done sucessfully and I've seen others done successfully too. Try to get an old cheap cylinder head or barrels that are in very bad condition cheap. You can then break off some fins and shape ready to weld on. Preparing this yourself is easy ready to get an expert to weld the prepared piece on.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline Pollock

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Re: BROKEN BARREL FIN REPAIR
« Reply #3 on: 19.01. 2007 23:26 »
I have used this method on an old 72 shovelhead. Looked okay but only lasted a season.  I agree I have a guy who did a good job welding on mine. It was a cast iron head. Looked good. I can't believe the heat from welding would distore the barrel. Especially on the top where it is where they are broken. My 2 Cents.
Pollock

Hi all,
Just took the A10 barrel to be refurbished (part of the top fin of the barrel is missing). The guy at the bike shop said he wouldnt weld it, as by doing so, the barrel could be damaged. He suggested that I grind back the remaining edges and then by laying some cardboard down on top of the next fin (to create the gap), I could use automotive putty and build a new fin, sanding and grinding the edges to match the shape. In other words a cosmetic repair. I am seeking your thoughts on this. Seems a bit shronky to me !
Cheers Ian

Online trevinoz

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Re: BROKEN BARREL FIN REPAIR
« Reply #4 on: 20.01. 2007 00:49 »
Hi Ian, I have had barrels repaired as described above. Find a sacrificial barrel and do as suggested. I get mine brazed but do this work before rebore as the bores will distort. Good luck.  Trev.

Offline terryk

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Re: BROKEN BARREL FIN REPAIR
« Reply #5 on: 20.01. 2007 12:35 »
I have repaired fins on barrels and heads with no worries. Brazing is the way to go use old barrel fins and shape them to broken fins then find small nuts at correct thickness to put under the new fin to hold it at the right height dont try and hold fins with fingers. Trev is correct bore it after all work is done because it could distort. If you have good bores you can spot braze it just enough to hold it. From the side you cant see it anyway and it shouldnt distort but check bores with mics. Terry
1950-53 A10 rigid/plungers, 1958-61 A10 super rockets, 1947-50 A7 longstrokes, 1949 Star twin,
1951-54 A7 plungers, 1940s M21, WDM20s,
1948-50s B33s rigid/plunger/swingarm, 1948-50s b31s rigid/plunger/swingarm