Took My Cylinders Off Today And Saw This!

[Steve S.]

Anyone have any explanation for why these would be welded like this?  I can't figure it out.  I have never seen anything like this before today.  They are only welded on one side of the flange, not all the way around.  With the cylinders installed, one weld is on the inside and one weld is on the outside. Any help would be great.  Thanks.

[moonpup]

My guess would be that it was the result of an accident that pushed both exhaust pipes in the same direction resulting in cracked flanges that needed repair. 

[Steve S.]

Yes.  On closer examination and more cleaning I can now see the extent of the repair.  The strange thing is not one finn was/is broken.  You can see just how far the repair goes in these pictures.  Any advice on what I should do, if anything?? 

[BS Mechanic]

Steve,
Could have been an accident, or it may have just been an overly aggressive tightening of the bolts, although you'd think whoever broke the first one would have figured it out before breaking another!
I must confess to cracking one once, but that was long ago when you could still buy cylinders from BS.

Those are the weaker style of exhaust flanges, at some point BS did design change that blends the flange in with the fins, sort of like the repair you have.  Made them much stronger and resistant to too much bolt torque.  This picture shows the difference between the two designs.

[Bikenstein]

The welds look pretty solid. You could clean them up some with a burr bit if you want. Looks like the welder didn't clean the inside port area very well before welding.

[Steve S.]

Wow.  I had no idea there were two different designs on the exhaust flange.  Sounds like they may have had a problem with early production versions.  It looks like a very old repair probably done back in the day.  I guess I will just clean up the welds, and try to blend them a little better.
Thanks for the input gentlemen.  I appreciate it.

[rocketman]

 Just be carefull not to remove too much material when smoothing them up Steve. The welds are likely to be superficial in areas. In other words like a bridge across the surface particularly around the fin areas.  Penetration might not be uniform and if the material is thinned excessively they may crack again.   Mark.

[Bikenstein]

The weld penetration looks good and it was back welded. The only problem I see is the interior port wall next to the weld was not filled properly. Be careful not to remove any more material adjacent to the weld in this area. You can use a JB putty stick as a filler here if you clean it well.