Electronics and Welding Advice

ok i need to weld a mount for a muffler onto a swing arm, i have a wire feed MIG welder

which is direct current from the electrode connection to the weld spot. so i am thinking it would be ok with the bikes electronics if i don't remove the swing arm from the frame

does anyone have experience with this and what are the issues with magnetos and electronic welding also another issue is i plan on draining the gas completely before i do this from the in frame tank but are there any other fuel system concerns except getting the fuel out

Thanks for any advice

Re: Electronics and Welding Advice

it's usually advisable to disconnect things like an electronic ignition module or other sensitive electronics.. although i welded a bunch of stuff on the frame of my car to get a trailer hitch on there, disconnected absolutely nothing and had no problems.

i'd be far more concerned with starting a fire.. Draining gasoline from some cavity that held fuel is not enough.. the remaining vapors are what will get ya.. Most welders wont touch any container that once held fuel .. The pores of the metal itself adsorb fuel and is released when heated. .. sometimes they fill it with water or do other stuff .. but it's still scary no matter what you do.

I'd think a swingarm would never hold fuel or be exposed to it so it seems safe enough... no reason to drain the fuel tank as long as it's protected from spatter or high heat.

(Insert long, boring legaleeze disclaimer here.. don't kill yourself or set fire to the neighborhood)

Re: Electronics and Welding Advice

ive welded something on to my ped and nothing happened

Re: Electronics and Welding Advice

I think it'd be safer to remove your swingarm and rear wheel, but I've never welded anything with electronics connected. I've heard of bearings being damaged from welding, something about pitting on the bearing surfaces, but I don't know for sure. Disconnect your battery if you have one, and possibly your ground.

+1 from joew, fire is probably more dangerous. You're heating metal up to 3,000 degrees C, with splatter going places, so don't burn the house down.

Didn't some kid blow himself up recently when using a propane torch on his 'ped?

Re: Electronics and Welding Advice

yeah .. it hit the papers.. in the General forum.

i've done lots of welding on my bikes but there's no CDI ignition or anything.

As far as damage to bearings, there's a chance of that but only if you ground the welder to one side of the bearing race and are welding on something electrically connected to the other side of the race..

The greased balls in between can make a momentary, poor electrical contact and there's an arc and something in the bearing gets burned and pitted.

Re: Electronics and Welding Advice

Jeff Strahle /

i welded a broken pipe mount on my tomos and absolutley nothing happened to it. i grounded the bike from the welder but still nothing went wrong.


Re: Electronics and Welding Advice

Clint Allison /

just make sure you ground the welder as close to the work as possible and you should be fine.


Re: Electronics and Welding Advice

As Clint mentioned, keep the ground clamp as close to the weld as possible or at the very least, make sure nothing electrical is in the path between the welding wire and ground clamp.

Welding near fuel tanks can be dangerous but just be cautious and remember that it's best to keep the tank downwind from the weld (hey, you're welding outside right?)... at the very least put an electric fan near the bike so that it blows any potentially leaking vapors away from the weld.

Although welding a gas tank can be dangerous I have done it several times but with the proper precautions taken. Flushing the tank several times with denatured alcohol (still flammable but cooler burning and not as violent as fuel) and then putting it in a 4-sided enclosure with an open top and then flooding the inside of the tank and enclosure with an inert gas like argon or CO2 (that wire-feed welder is set up for MIG too, not just flux core wire, right?) while welding will prevent residual fuel from igniting.

Re: Electronics and Welding Advice

Allen Murphy /

Yep--I had the gas tank from my Yamaha welded, and we put dry ice inside, and TIG welded to our little heart's content.

Worked great, and no more leak!

Al Murphy

Re: Electronics and Welding Advice

are you actually welding on the tank itself?

dont forget to cover everything in the surrounding areas with a fire retardant cloth. most especially if you are using flux cored wire instead of gas. spatter will get what the heat wont.


Re: Electronics and Welding Advice

No I'm not actually welding to the tank. i am extending the exhaust mount and yes it is a MIG setup as well. by the sounds of it it is ok to do as long as i have the ground positioned before any electrical contacts on the bike. and I'm not to worried about splatter as this will just be a few short burst to tac on an extension.

Thanks everybody

Re: Electronics and Welding Advice

Be careful putting a exhaust mount on the swing arm. The swing arm (obviously) goes up and down as you go over bumps. If the exhaust is attached to it, it will want to go up and down too, which will break the exhaust mount on the cylinder.

(I have had that happen)

You're brave to Weld Gas Tank

Wow, you're one brave dude. Maybe I'm just not good enough a welder but I'd take it to a pro. The risk of welding and blowing up the tank (and sending me to a hospital) is too great for me. I'll stick to welding inert objects.

Do be careful, dude, and all the power to you for advanced welding.

Re: You're brave to Weld Gas Tank

Normally when the moped isnt running, there is NO current going through it. Therefore, you CAN use the moped as a ground no problem.

If, however your moped has a battery grounded to the frame, then disconnect the hot-wire. Just make sure it doesnt hit the frame or you'll short something out.

Like caleb said, be careful welding exhausts and such to the swing-arm if you're using a spring/shock suspension. If, however you're using a hard-tail (suspensionless rear end) then you'll be all set.

Go nuts.


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