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  • motorcycle frame

    Pardon me this might be a bit wordy...

    I have started a new project chopping a old Suzuki GS450. This will be my first project where the welds need to be strong AND look good. It is also something that I will not have many chances to practice doing before I actually have to do the real thing. I might have 1 or 2 practice attempts with the materials I have. In the past either my welds didn't have to be so pretty or I had plenty of time to practice to get it dialed in correctly. So I'm coming here looking for advice from people that may have done this before or something similar hoping to gain as much knowledge as I can before I start.

    So here's the situation. I'm extending the downtubes on this stock frame by 1 1/2". I've cut out 2 1/2" and I will be replacing that with 4" extensions. The stock frame is very thin, 1 1/8" outside diameter with a 1" inside diameter and is probably made out of ERW tubing as it definitely has a seam. The extensions are DOM tubing but with a thicker wall, 1 1/8" outside diameter and a .875 inside. I made slugs out of solid 1018 mild steel and turned them down so they would fit inside the extensions and stock frame. The extensions and stock frame will be drilled for rosette welding to the slugs and the seam where the extensions meet the frame will be beveled.

    My question to you folks is what settings would you start with to accomplish this using a Hobart 187?

    Here are some pictures to illustrate what I am talking about.

    Downtubes on frame cut:

    Extensions with the slugs sleeved in. Extensions are now drilled for rosette welding to slugs but that is not pictured:

  • #2
    Ok...I'll start the discussion. I think I'm going to start with 3/50 for the settings. Discuss!


    • #3
      The slugs look good! Just go by the chart on the door of the welder for the thickness of the slugs. Just be sure to clean and bevel the frame tubes also.


      • #4
        Originally posted by Tinymx View Post
        The slugs look good! Just go by the chart on the door of the welder for the thickness of the slugs. Just be sure to clean and bevel the frame tubes also.
        I think you mean the thickness of the extensions, the slugs are solid between 1 inch and 7/8 thick. I think you would want to set something higher than the thick wall tube settings since the slug will draw a lot of heat out of the area.

        Make adjustments after your test weld and walk away form the project if you fail your test.


        • #5
          Have you stretched a frame before? I suggest hauling in a couple junkers to practice on first. Its not only the welds (which are VERY important), but the resulting alignment and geometry

          I call your 'Rosette Welds' "Plug Welds", but call' em whatever, they are the same. I am no expert, but offer these suggestions with about the same authority as the kibbetzers encountered at any Swap Meet or car Show (the guys I refer to as "The Judges")

          Be sure to clean out the inside of the tubes (a round wire brush should do it) to get those as clean as possible.

          Just like Ferntj suggests, a setting higher than the tube's thickness, but you don't have a lot to play with here. The trick will be to get a good 'melt' going on the slug in the center of each hole, letting it migrate outwards to the tube at those plugs. The same setting should accomplish your edge welds...

          I assume that motor is going to be removed first for access, to permit one continuous weld around the tube.
          "Good Enough Never Is"


          • #6
            Considering the slug is a fairly healthy chunk of solid stock, I wouldn't recommend using short circuit transfer or a self shielded fluxcore for producing the plug welds. TIG would be my recommendation.

            BTW, its hard to discus machine settings of 3/50 without including such info as what diameter wire your running, and whether you're running solid or fluxcore wire. If you're running solid wire which shielding gas are you using?
            MigMaster 250- Smooth arc with a good touch of softness to it. Good weld puddle wetout. Light spatter producer.
            Ironman 230 - Soft arc with a touch of agressiveness to it. Very good weld puddle wet out. Light spatter producer.

            PM 180C

            HH 125 EZ - impressive little fluxcore only unit


            • #7
              Thanks everyone. I apologize for not including the wire size and whether or not I was using gas. I was checking this forum regularly for a few days and then got sidetracked and figured if I had a response I would get an email. Unfortunately I did not have it set up that way. I am using solid .030 wire and C25 gas. My test welds went well and I'm confident things are going to work out well. The welds will most likely not be done as one continuous weld. To answer the question on whether I have done this before, no I haven't. I have however done a considerable amount of reading on how to do it by people who have done it before. You are right, alignment is very important but by keeping the motor in the frame while working on the downtubes will help keep things aligned and as long as I'm careful to stretch each tube the same that shouldn't be an issue. It will certainly not be my biggest worry, I'm sure that will come when I weld the hardtail on it and cut out the swing arm. Also, I do realize that TIG might offer more control and precision but it's simply not what I own or know how to do at the moment.

              So with my test welds I learned a few things. I learned that I probably shouldn't have beveled the edges of the tube so much. The angle was probably near 90 degrees. This wasn't ideal and made me move a bit slower than I would have liked for the weld puddle to fill it in completely and for me to achieve the proper overlap. I had to turn the wire feed down a bit. I learned that it's fairly difficult to weld around something so small in diameter. And also the importance of having the gun slightly angled up.

              I'm gonna try to finish the extensions this weekend. I'll post pictures when I do.

              Thanks for the responses.


              • #8
                My suggestion is, "Don't even attempt what you're planning".

                If you ignore said advice and proceed anyway, call your insurance agent and take out additional life insurance. No reason the family should have to suffer from your misguided actions.

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                • #9
                  Originally posted by SundownIII View Post
                  My suggestion is, "Don't even attempt what you're planning".

                  If you ignore said advice and proceed anyway, call your insurance agent and take out additional life insurance. No reason the family should have to suffer from your misguided actions.
                  Can you explain why you think that what I'm planning is so extremely dangerous? Better yet explain to me how my actions are so "misguided". If you have experience with this and want to share why what I'm doing is wrong please do so, I'd really like to hear it. But to tell me I'm misguided and not explain why doesn't sit well with me.


                  • #10
                    Hey dedfish,
                    Just want to provide personal input as to your project & just some simple "food-for-thought". Don't misunderstand SundownIII's response or feel castigated about it....the truth is found in the intent.

                    First, as a hardcore biker(54yrs) & weldor(47yrs), I would interpret your initial posting as a query to validate your procedure. I also noted that there were over 100 views of your posting before a response. Looking at your project, parameters of modification, & your intended procedure, I would also agree with SundownIII.... reconsider prior to engaging. Get some professional offerings from a knowledgeable source, not some postings from forums of those experimenting/learning a quite dangerous alteration to a frames' structural integrity. Do you have any knowledge of the lateral/weight/stress/flex parameters of a frame? All these factors must be engineered to insure SAFETY! Any modification of any of the parameters change the motorcycles' operation. Just do some serious homework..... you may learn something not considered. Even with all my experience, I have never welded on a motorcycle frame.....that's my choice. You have to live with your choices & decisions & results of those.

                    Complete weld/mach./fab shop
                    Mobile unit

                    "A man's word is his honor...without honor, there is nothing."

                    "Words are like bullets.... once they leave your muzzle, you cannot get them back."

                    "I have no hesitation to kill nor reservation to die for the American Flag & the US Constitution."


                    • #11
                      I'm not sure why some folks are wary of welding on a motorcycle frame.

                      A motorcycle frame is every bit as essential for safety as a car frame which backyard weldors have been doing for years. I've seen some built from scratch car frames that were welded in a backyard that were works of art and as strong or stronger than a factory welded frame.

                      If you know what you are doing and have a good welder, then welding on a motorcycle frame is not that hard to do and will be as strong or stronger than a factory frame. And don't forget some of the Suzuki frames that were prone to fall apart at the welds from the factory. So if done right, there is no problem welding a frame for a motorcycle.

                      Your inserts are a good idea but how are you going to put an insert into tubing that is longer than the space where it is to go into? Problem is the inserts are longer than the space that they are to bridge. Not too sure that your inserts are going to be able to be inserted!

                      I did the same thing a few years back. What I did was find a tube that fit inside the frame tubing. I bent the frame a bit to fit the tube into the bottom of the frame tubing and then bent the frame back. I then was able to move the insert tube into the upper part of the frame and then welded it in place. I then took a tube that matched the outside diameter of the frame tubing and cut it in half. I then placed the two halves over the insert and tig welded it. I then ground the weld down and you could not tell that the frame was even welded.

                      Everyone has their firsts. Their first welding machine. Their first car.
                      You've got to start somewhere and extending a frame with a Hobart 187 is doable and not that difficult.
                      Cobra 2000 A/O torch ( all USA made)
                      Everlast Powertig 250EX (US company, Chinese MFG)
                      Everlast Powerplasma 50 (US company, Chinese MFG)
                      Hobart Handler 210 (US company, Chinese parts)
                      GoWeld portable mig (US company, Chinese parts)
                      Evolution rage 2 cold saw (USA company, USA parts)
                      various other metal working tools


                      • #12
                        I'm staying out of this except to say that the old 'zuki is a worthy candidate to experiment on.

                        That motor has seen some serious white rust.

                        That era bike already has some 'gobby' welds on the frame lugs. The Japanese were 'practicing' as well early on.


                        • #13
                          You are on the right track.

                          I would not make this repair the way you are doing it.

                          I would not use solid slugs.
                          I would use a die grinder and remove that welding seam as best as possible inside the tubes.

                          The Outside of the tubes need to be sanded to clean shinny metal.SANDED not grinded!!!

                          Then get a TUBE that fits inside the 1.125 frame tube. Make sure it is CLEAN shinny metal. Where the weld seam is located you may have to grind a little groove on the insert to accommodate the weld seam.

                          The reason to use the tube inside instead of a solid bar is it has more area surface and is strong and will weld very well.

                          This is a very common motorcycle frame modification.

                          I would TIG weld it. Just tack it with your MIG and take it to a pro.
                          If you weld it with your MIG turn it all the way up. 1.125 is the limit for that 110v welder.

                          Make sure to drill a hole for a 1/4 inch rod to go through the tubes on each side of the tranverse weld. Weld both ends of the 1/4 inch rod.
                          Last edited by donald branscom; 03-19-2011, 07:52 PM.


                          • #14
                            I used to run a bike shop in the early eightys. I did the same project using a 500 Suzuki Titan. I welded everything up in stick (7018 3/32) then ground the welds smooth before paint. The old ratzuki is still on the road today with no issues. I didnt use slugs,just butt welded everything together.The only issue I have with your project,is the use of your baby mig.I think more heat would be a better choice. Like I tell the guys that I teach to weld on the boat in the winter......penetration is everything

                            just my opinion