ASK THE MXPERTS:
2007 YAMAHA YZ250F FRAME CRACK
My 2007 YZ250F has a crack in the frame near the head tube. It follows the factory weld going down the down tube about one inch long. Is this common? I have been TIG welding aluminum for years, but will it weaken the frame if I try to fix it myself?
In our opinion, this is cold weld issue at the factory level.we don’t consider it common, but MXA has personally seen four frames with this issue (and that is enough to convince us that everyone needs to inspect their head tubes regularly).
Yamaha does not recommend welding the frame and before we suggest that you weld it, you should go to your local Yamaha dealer and try to see what Yamaha Customer Service will do for you. There have been cold weld issues on Yamaha frames in the exact spot that you are describing.
If you want to weld the crack, here are some tips from Yamaha (although we suggest you consult an experienced welder in your area). Drill small pilot holes at each end of the crack and use a grinder to chamfer the holes. This will stop the crack from spreading underneath your new weld. Before welding the crack, take the time to preheat the frame over a fairly large area. You should be able to heliarc the crack with little or no trouble. The series-7000 aluminum will heat-treat as it ages. This should only be attempted by a certified welder and with the correct rod. In other words, we don’t recommend that you do it without professional advice.
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