Motorcycle header crack fix

[hmhoek]

I have an old BMW boxer with a circumferential crack in the exhaust tubing about 8 inches from the head. I also happen to have a spool of .045" silicon-bronze MIG wire laying around. I'm wondering if this is suitable for filling the crack and what kind of prep would be required.

I have some pure argon, and a big tank of c25 available. I've read that argon is the way to go with silicon-bronze. I'm also thinking of grinding out the crack with a dremel wheel, which would leave a gap of around 1mm or a bit more. The crack doesn't go all the way around, so ideally I'd tack it in place, then remove the exhaust and finish the job on the welding table.

I have MIG and TIG, but I'm leaning towards TIG for this job.

[Guest]

Sil bronze isn't very strong, for your application...it'd crack soon. Try to use the same metal as the base material, and you'll be good to go.

[SidecarFlip]

If I'm not mistaken, the older Beemer pipes were mandrel bent HRP with a welded and ground butt seam then triple chromed.

British Customs in Garden City, Michigan would probably be able to get you a new one, or Engles in Kansas City. The heat/cool cycles over the years have embrittled the grain structure. I don't believe any repair will be long lasting and it won't be 'pretty' either, but then I'm into vintage restorations.

[Zrexxer]

If you have a crack like that the material wall thickness has eroded in the bend so much that there's nothing left to weld to anyway. You can get nice replacement aftermarket header setups for about $200 and that's definitely the way to go.

I had a set of Mac's on my R100/7 and they were as nice as OEM.