Weld advice... to grind & redo or not?

[Nitori]

Just got my '71 CL100 frame back from the sandblaster. Looking at the welds, some of them definitely have some contamination, but I was hoping the more welding savvy folks could dish out some advice on how to best handle some of these. Cosmetics vs functionality I'm also a bit hazy on. Would it be dumb to "cover up" ugly spots that are not structurally unsound?

Granted all of them have held just fine for the past 45 years, so maybe I should just leave 'em all be...

Swingarm:

Good to go all the way up till the end. I don't doubt this one's safety, but it's ugly and will be easy to see.

Battery Pan/Airbox area:

This one is probably the biggest whiff on the bike, but it's also going to be hidden under the seat.

I'll have some more pics tomorrow, I took some of the other problem areas but they turned out crappy and I'll re-do.

 

[my-79-750-k]

They don't look like they would cause a wreck, just ugly. The swingarm would take a welder about 10 minutes to grind down, fill up and smooth over. It will also keep it from rusting internally by sealing it up. The battery box is just ugly, plain and simple. I'd grind it down and re-weld it. It looks like a small weld area so again, a welder could do it in a matter of a few minutes. (Unless you weld, that is.)

 

[hillsy]

If that 2nd one is a factory weld its must have been done with a sticker welder on a Friday afternoon after a hot saki lunch....

 

[J-Rod10]

Glazing putty on the swingarm is a quick fix. The other, I'd grind and reweld.

 

[Nitori]

If that 2nd one is a factory weld its must have been done with a sticker welder on a Friday afternoon after a hot saki lunch....

It looks like the entire thing was stick welded. Funny how you look at the CL100 engine and it's this neato, slick engineered little mill that they kept relevant and alive well into the 80's, then the frame is just sort of... well here's some stamped steel and tubes stick welded together.

This one definitely needs a redo, as it's probably the most suspect one.

In all fairness I'm not trying to totally poop on welder-san, the majority of the bike is totally sound, if not the most aesthetically appealing:

 

[doc_rot]

Dunno what welding process you would plan on using but Tig does not like the Japanese mig welds from my experience. Personally I would Tig braze over them with some silicon bronze, it will wick into those pores nicely and it sands very well.

 

[Nitori]

Dunno what welding process you would plan on using but Tig does not like the Japanese mig welds from my experience. Personally I would Tig braze over them with some silicon bronze, it will wick into those pores nicely and it sands very well.

My only experience with welding is looking at welds, so go easy on me. I understand the basic concepts, how they can go wrong, and what a bad weld looks like, but I have exactly 0 minutes experience on a welding machine of any type.

You mentioned brazing, I know TIG brazing is a thing, but I'm going to guess that low temp brazing (like with a propane or oxy/mapp torch) isn't gonna cut it? If it would, I guess I could just grab some low temp brazing rod and go to town over the existing joints with just a quick pass of cleaning before I start?

I do know how to solder electronics, so that would be a semi familiar process for me, just with a torch and a rod instead of an iron and "rod" of lead/tin.

My other option is to take it to a body shop place that does work for me and throw myself at their mercy to see if I could get it done at a reasonable price, since most everything is just fixing 1/4 inches of welds here and there. I'll be sure to mention about the silicon bronze.

 

[doc_rot]

I'd be surprised if the body shop was doing any TIG brazing, its kinda tricky and a slow process compared to MIG, which is likely what they are using. I don't have any experience with traditional brazing so I can't help you there. If you dont have the tools/experience to braze it yourself I would just use some body filler and be done with it. its very unlikely that the welds would fail despite how they look, steel is VERY forgiving.

 

[xb33bsa]

those are just typical production welds for that era of jap bike,nothing to worry about, move along, just paint over them,be done

 

[Nitori]

OK so I guess the consensus is to just leave 'em be, but if I want to pretty them up a bit, which is more acceptable for powdercoating over- body filler or brazing?

I know both aren't exactly cheap, the filler is decent $ and so are the brazing rods, so I may just call it a day and get it powdercoated as it stands.

 

[xb33bsa]

pretty them up ? nobody will notice ,huge waste of energy
put the time effort and money into improving the motorcycle itself the rewards are actually something you can use

 

[jpmobius]

those are just typical production welds for that era of jap bike,nothing to worry about, move along, just paint over them,be done

Yup. Nothing whatever to worry about there. Those are MIG welds and the defects are likely from the shielding gas going missing for some reason.

However, a very little bit of work will go a very long way if you want the frame to look better. The first thing is to cover up that bare metal immediately! If it is humid where you are, this is really important. It is super humid where I live, and I epoxy my frames within minutes of sandblasting them or they get rust percolating through the paint years later. Spend an hour with a couple of files and smooth off the really bad welds, and then as already mentioned, smear some glazing putty (or polyester body filler like Bondo would be better) over those porosity holes with your finger and sand smooth. You don't have to be super fussy to get a big improvement - just depends on how picky you are. The manufacturer thought it was fine as is and just painted it, but just a little work will make it a lot nicer. If you powder coating talk to you vendor first as you likely will be wasting your time filling any defects.