Topic: Removing a tack weld

[eigenvector]

Come to find out the previous owner of my bike removed the stock baffles from the muffler and tack welded in their own open system.

Fair enough, but I want to put the original baffles back in - question is, what's the best way to remove a tack weld on a circular object like a muffler can?  Sure sure, I can/will grind off the surface mounds - but undoubtedly the insert and the shell have been welded inside.  I don't want to grind off huge chunks of muffler shell trying to break the weld - and one of those welds is REALLY ugly - like "I don't know what I'm doing, but I'll tack weld it anyway" ugly.  I only welded as part of my engineering curriculum - and I could have done better than what they did.

So my question - if I do grind off the surface weld, will that likely be enough to separate the shell from the baffle? 

I'll snap a photo and upload so you have an idea of what I'm talking about.

[eigenvector]

The welds in question

[madmtnmotors]

I think once you grind the surface down you will find that there was not much penetration of those welds. You should not have to go too deep, and it might fall out once you grind the surface off.

[chewbacca5000]

I agree.  Remember it is not legit unless there are some sparks.

[eigenvector]

Kind of why I was asking Cal.  But - no harm grinding them down flush with the top of the shell.

Funny you guys mentioned sparks - that "baffle" if that's what you can call it, was running so rich that the tip of the muffler was coated in about 1/4" of oil, sludge, gas, you name it.  No spark arrestor on this baby!

The other one isn't as bad as this one - I'm guessing the shell being out of shape made it difficult to tack.

The thing that annoys me - those small holes in the baffle are the mounting holes, why the heck didn't they just use them?  3 or 4 pop rivets and no need to tack it.

[eigenvector]

Well one of them is out.

Almost got the second one but I ran out of Dremel discs.  Will make a store run in a bit.  The first one is sitting in the Berryman's can to get rid of all that spooge that collected on it over the years.

Welds were pretty shallow all told, that big mountainous one went pretty deep, but it was also real gloppy and so once you started to cut through it the rest cracked and gave way.

Like I say - I don't have a clue why they didn't just use the mount holes - they're right there staring you in the face.  Instead they burned through the shell with terrible welds.

Glad I got the grinder - made short work of the surface welds, making it quicker to dremel out the cracks.  Also glad I wore my faceshield - dremel disc shattered throwing fragments into my face. 

The surface finish wasn't a concern for me Cal - the welder took care of that long before I ever got it.  That said - when it's done I'll need to thoroughly degrease, clean the metal of any remaining tack weld spots, and then hit it with high-temp paint.  Or it will rust.