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Aluminum Weldability -CR 250 Trans cover

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  • MIKEDOGG
    started a topic Aluminum Weldability -CR 250 Trans cover

    Aluminum Weldability -CR 250 Trans cover

    I believe that the trans cover on my Honda CR 250 is made of a cast aluminum (correct me if i am wrong) and I am wondering if i can tig a small crack that has developed.

  • bob_e95482
    replied
    I just welded a Kawasaki cylinder head, with excellent results, with my Dialarc HF.

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  • zmotorsports
    replied
    MikeDogg, this is not a bad repair if you take your time and don't get in a hurry. I do quite a few of these on bikes and especially ATVs where the front sprocket is close to the transmission/engine case. The clients will try to skimp on chain quality and/or maintenance and the chain will break and wedge between the sprocket and trans and blow a hole in the case.

    Usually the customer will still have the piece or it is somewhat still attached and can be put back in place with little effort. Sometimes I have to fabricate a new piece to fill the void.

    Either way cleanliness is the key. I haven't had the best luck of V-ing the already thin casting. I generally clean in the solvent tank after disassembly, spray with a non-clorinated (make sure it is non-clorinated) cleaner, lighlty run a Roloc disk over the area to remove the surface irregularities and then I will use a heat gun to try to extract as much oil from the casting as possible.

    I then make a small bead alongside the crack preferably on both sides to "float" the impurities to the surface. One thing I have had great results with is to set the machine to pulse at a high rate if you have access to an advanced squarewave machine. This greatly helps to get the impurities to the surface. After making the preliminary passes, wire brush the surface very well and then fuse the area together generally 4043 rod seems to work the best.

    Also, depending on the size of the case half (some are quite large and do a good job of dissipating the heat and others are very small and can warp fairly easy. If the part is on the smaller side I clamp it to my welding table to act as a large heat sink and also to help it hold it's shape with less chance of distortion.

    After the part has cooled and the repair looks solid I run it across some sandpaper that I tape down to my surface table and lap the part to make sure it is perfectly flat. No sense in going through all that work on one leak and create another.

    Good luck, Mike.

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  • FusionKing
    replied
    Originally posted by MR.57 View Post
    FK if you've got the "secret sauce recipe" for Honda's motorcycle case alloy I'm all ears. I've had good results with H-D and Kawasaki, but Honda seems to be a different animal.

    It corrodes to a Dark gray like Magnesium, but it isn't Magnesium. How do you correctly match a filler when you have no idea what alloy it is? Honda does occasionally use pure Magnesium for outer case parts on their racing bikes (HRC), but this was a factory part.
    Seriously I haven't had much trouble with bike parts either. The main thing I do is after clean I run a puddle on all the edges of the crack and re-brush any crud that floats to the top. Then flow again and if the puddle is shiny, then it is fine to weld. Mag or aluminum either way. Just the mag ones are a bit scary IMO because I don't do it everyday but actually I have had great luck on mag parts for years. I like to use sine wave on castings and keep the balance and hz down as well to take full advantage of the cleaning the machine can do.
    4043 is all I've used on almost all those and seriously I don't recall the mag rod I have had forever, but it is very expensive.
    Now all that said I'll give you a bit of wiggle room here. I have done bunches of Honda stuff but I may have never done the exact case you are referring to.
    From my perspective, if a guy brings me a part, I am gonna do my dangdest to get his money. We did have one local welder that would weld your pontoon and then coat his work with JB. I pretty much took every customer he had that hadn't run him off.
    I truly wonder if that cast was very high in mag and if so how a mag richer filler would work. That I have NOT tried but as of yet never needed to. I cannot find anywhere something like 5356 is recommended for a casting, altho I have heard people speak of it. Temp would make it a problem anyway.
    You can bet I will be looking specifically for a CR250 repair now just because I am curious. I fix loads of their other stuff. Like outboard lower units, PWC engine parts, and small motor and ATV engine stuff.
    BTW, I'm never sure what any casting I am dealing with as far as actual composition. It would be nice to know but seldom practical to pursue on my part.
    If you (or anyone) finds Honda's composition info on this I would love to here the answer myself. Always looking for an edge.

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  • Portable Welder
    replied
    Aerometal worker please elaborate about yor little machine, What size part does it hold.

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  • MR.57
    replied
    Originally posted by FusionKing View Post
    OMG!!!!! Is there a JB Welding forum out there???? Any crap that hinders welding stops good epoxy adhesion as well.
    If you only knew how much of that CRAP I have removed by folks with good intentions only to find they have simply making the job they should have done in the first place much more dificult.
    FK if you've got the "secret sauce recipe" for Honda's motorcycle case alloy I'm all ears. I've had good results with H-D and Kawasaki, but Honda seems to be a different animal.

    It corrodes to a Dark gray like Magnesium, but it isn't Magnesium. How do you correctly match a filler when you have no idea what alloy it is? Honda does occasionally use pure Magnesium for outer case parts on their racing bikes (HRC), but this was a factory part.

    Leave a comment:


  • Aerometalworker
    replied
    Ive never had any issues with bike parts. Last cover I checked had somewhere around 12% zinc ( easy to believe with a die cast part ). 4043 or 4047 were appropriate in that case. One of the best investments I ever made was getting an ultrasonic heated cleaner to rattle aluminum castings clean, its a night a day difference. Always used one at work....finally had to shell out for one.

    Leave a comment:


  • Portable Welder
    replied
    Fushion King, Evidently we must be lucky welders.

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  • jardine
    replied
    I'm with MR.57. JB weld it. I've HAD to do it to quite a few of them over the years. I've tried to weld a few of them with poor results due to contamination and warpage. Once they warp you'll never get them flat enough to seal. I built a jig for one, 1/2" steel plate that allowed me to bolt down and weld and sit till it cooled. Worked great. It was for my own bike. The only problem is it wasn't any better than the JB fix and I had quite a bit of time invested. The other option is just to buy a new one or find one in a junk yard. Tons of CR 250s out there and chances are you'll have to anyway once you start welding on it.
    I don't think I've owned a bike, or my family that dosen't have a little JB some where. There's places for JB and places where welding is a better solution.
    Jerod.

    Leave a comment:


  • Portable Welder
    replied
    Mr. 57,

    Did you send your parts out to a metalurgist to find out that they have a high magnesium content.

    You may also want to research ( Welding dirty aluminum )

    Fushion king is right, I also get alot of people trying to save money with JB Weld and by the time it gets to me the repair cost is double because 1/2 my time is spent cleaning the JB weld out of the crevice.

    Leave a comment:


  • FusionKing
    replied
    Originally posted by MR.57 View Post
    Most of the Honda motorcycle "aluminum" castings I have worked with seem to have an unusually high magnesium content. Whatever exact alloy Honda's using, it doesn't weld like the A356 that most automotive stuff is cast from. Oil contamination just adds one more problem variable. Call me a chicken, but I'd stop-drill the crack, epoxy over the thing and call it done. It isn't structural so a 100% strength repair isn't necessary.
    OMG!!!!! Is there a JB Welding forum out there???? Any crap that hinders welding stops good epoxy adhesion as well.
    If you only knew how much of that CRAP I have removed by folks with good intentions only to find they have simply making the job they should have done in the first place much more dificult.

    Leave a comment:


  • MR.57
    replied
    Most of the Honda motorcycle "aluminum" castings I have worked with seem to have an unusually high magnesium content. Whatever exact alloy Honda's using, it doesn't weld like the A356 that most automotive stuff is cast from. Oil contamination just adds one more problem variable. Call me a chicken, but I'd stop-drill the crack, epoxy over the thing and call it done. It isn't structural so a 100% strength repair isn't necessary.

    Leave a comment:


  • Portable Welder
    replied
    Mike Dogg, You might want to search welding dirty aluminum.

    The dirt on the welding rod is nothing in comparison to the dirty oil soaked aluminum.

    I never clean my alum. welding rod, I never let it get dirty.

    Magnesium is the only rod I clean because it oxidizes in my sealed rod holders.

    I dont recommend vee grooving thin covers beforehand, it will naturaly vee groove as your cleaning the black sut out of the crack when trying to pull the contamination out of the aluminum.

    Leave a comment:


  • MIKEDOGG
    replied
    Right on, good news. I appreciate your responses because today I am taking the bike apart. Excellent advice on thoroughly cleaning the cover after disassembly and before prepping bevel. Also thank you for the words of wisdom with regards to electrode stickout, post flow minimum and cleaning of filler metal with acetone. I will post pictures of the crack and the weld. Thanks.

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  • Suvi
    replied
    When welding aluminum with TIG, don't let tungsten stick out of the cup too much. Try no more than the diameter of the tungsen. And use atleast 1sec of post flow for every 10amps. So you will not contaminate the tunsten. I use these procedures and works for me every time. And ofcourse keep workpiece and weldingrods clean. Right before welding wipe the rod clean with acetone and clean the piece with stainless steel wirebrush.

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