aluminum crank case repair?

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Hi I was wondering if you guys can enlighten me on how to repair the cracked aluminum on my yamaha dirt bike crank case. I was wondering if this can be aluminum brazed.Thanks.Richard Attached Images
Reply:You sure its Aluminum?  Could be Magnesium. Magnesium is sacrificial in the electrolosis/galvanization dissimilar metals reaction.  Mag doesnt spark but someone here recently had a better test. I think he scraped some mag off and checked to see if it ignited.I know KTM's use Mag for that part.OOps, I meant cover not case but if you know how to tig it , then possibly.Last edited by Insaneride; 03-31-2015 at 11:19 PM.
Reply:I have a tig but it does not do ac welding so I was thinking of maybe brazing.
Reply:I dont think theres much pressure in the crank  so I think brazing should work . Do you have a way to machine it after brazing? A file would probly work if you have a surface plate. Also, I would make sure it is aluminum
Reply:I am almost sure it is aluminum as it is a soft material but what do you mean by pressure. BTW the case is from a yz250 2 stroke.
Reply:Never mind about pressure, theres always a crank ventilation or pcv . Iwas confused. Ive road a yz250. Weak suspension caused me to bottom out about the same place as yours. Wasnt mine tho, dude wanted to try my KTM. Cant beat upside down Whitepower or OHLINS suspension on a bike.I would do a test to see if its ally before you braze. I dont think alluminum rod will stick to Mag. If it is mag (probly not) , I would find a scrap magnesium from a bike shop and cut it into filler rod and TIG with Helium if your confident at TIG.
Reply:So is brazing easy to do?
Reply:If you have an OA rig with the rite tips stuf. VICTOR has a free book that tells what tips/pressure etc for metal thickness and all.  I think everyone would agree to TIG tho.Im no expert but wanted to give you heads up on magnesium.
Reply:Originally Posted by bridgeport13bI am almost sure it is aluminum as it is a soft material
Reply:Probably aluminum but some of the covers are magnesium. If I recall magnesium has a green tint when TIG welding. I can say that it for sure can be TIG welded good as new by a qualified welder. I know a guy that does stuff like that all the time.
Reply:Did you check ebay for a used replacement half?Often under $100 depending on model and year.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:pull out the white vinegar and pour some on the case..if it bubbles its magnesium, if it just looks wet like water its aluminum.....Of all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:Originally Posted by bridgeport13bSo is brazing easy to do?
Reply:To the OP. If you put your location maybe others might be able to help locally.www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:Originally Posted by roadkillbobbpull out the white vinegar and pour some on the case..if it bubbles its magnesium, if it just looks wet like water its aluminum.....
Reply:Originally Posted by TJSTo the OP. If you put your location maybe others might be able to help locally.
Reply:That you can just jb weld becuase that's the ignition side. Just try to keep it water tight. Put extra on and fill it down then use silicone on the gasket when putting it back together. Why did you take the whole thing apart?
Reply:I might be able to help you out...if the part is spankin' new clean.  I can't help on machining after the weld repair though.  I am in Lakewood.-AaronJet 17.5" Drill Press1942 South Bend 16x84 Lathe1980s Miller 320A / BP --- 2013 Power Mig 2562012 Jet 7x12 Horizontal BandsawVictor O/A Setup
Reply:Put some silicone in where the shifter seal goes throught. That looks like it almost won't leak anyway
Reply:Thanks for all the help everyone, I may take up your offer rabidchimp but I may try to braze it.ThanksRichard
Reply:97-98 cases? 93-98 should work as a replacement.  They are all aluminum.Don't try to braze it, weld the missing stator chunk. Just epoxy the chain rash, Welding may distort the bore. Though If you can re machine it go ahead and weld it as well.