Posts
192
Joined
7/13/2014
Location
GB
Edited Date/Time
6/19/2018 10:10am
Hi guys I've recently bought an rm 125 2003 model. The bike is a really good bike. All fully rebuilt etc. The only issue is. The first time I rode it the gear shifter went very floppy after a couple of gear changes. I've stripped it down and the locating pin that sticks through the selector fork has snapped of from the casing. I'm not sure what this part is called I'm sorry. I'm just after some advise.....
Can this part of the bike be welded or is it going to have to be a new crankcase. I'm really annoyed as the bike is absolutely immaculate apart from this problem.
Any help/ advise would be greatly appreciated
Can this part of the bike be welded or is it going to have to be a new crankcase. I'm really annoyed as the bike is absolutely immaculate apart from this problem.
Any help/ advise would be greatly appreciated
I would not have that welded. Its too critical of an area, the weld would need to penetrate a good ways to hold which could cause warping... and that could cause other shifting problems. Not worth the risk in my 2 cent opinion.
Now with all that said, new cases are $700+ if you can find them and used cases are hard to find on ebay. You might get lucky and find a parts bike on CL.
Or I hope you know a very good welder. Good luck. keep us posted.
-Bob
The Shop
OP, good luck on the search for a set of case halves or a massive effort to have it welded and repaired.
The reason they don't weld easily is contamination (from oil, etc) and the type of alloy used in those castings (high silicon).
OP, you should just find a case, or a complete used engine. If that's not possible, welding & machining won't be inexpensive, but it will work if the job is done correctly.
Baking the casting for a few hours (when your wife isn't home) can help, then clean it a few times with a good non-toxic de-greaser (don't use chlorinated brake cleaners, etc. where you'll weld).
Get a guy who is skilled on the TIG welder and has experience with aluminum castings.
You'll have good luck with 4047 or 4043 alloy filler rod.
Rather than weld that piece back in, you need to build it up and then have a machinist mill it flat, drill, then tap the hole.
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