Need Help Someone (poorly) welded a sprocket on this bike..

Wolfweyr

New Member
Hey guys, new to the forum.. I recently purchased two FZ6 bikes (2006, and 2004) one had blown head gaskets and a lot of other issues but good frame with a title, the other had a "good" motor but no title for the frame. (VIN verified, it's not stolen)

Anyway, I was doing an engine swap and cleaning up the titled frame, got as far as dropping the good motor out of one of the bikes and then found that someone literally welded a nut, very badly, to the threads to hold the front sprocket on.. is there anything short of tearing this motor down that I can do to fix this?

I'm not a new mechanic, but I'm definitely still learning..
 

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TownsendsFJR1300

2007 FZ6
Site Supporter
That IS nasty.....

Obviously the correct way to repair is a tear down and replace the shaft.

If your really careful with a cut off wheel, you can grind that "weld" off till you get to fresh metal.
Shouldn't be too bad as it's very bad...

I would replace that sprocket(with steel) and have it re-welded by a competent welder. I would also try to rig up something to keep pressure on the sprocket when the welder goes at it..

That'll get ya another 25K miles if maintained
 

Wolfweyr

New Member
Thanks man. I think that's not a bad idea tbh. I was planning to rebuild the other engine properly for a good swap. I think having a competent welder get a good weld on a new sprocket is the way to go for now until I get the other engine built as well.
 

TownsendsFJR1300

2007 FZ6
Site Supporter
For welding, if the engine is out, it'd be MUCH easier for the welder.

The shaft splines take the brunt of the torque, the nut just keeps it attached to the shaft from falling off. That's apparently what happened previously..

.
 

Gary in NJ

Junior Member
Site Supporter
I think that weld has monkeypox. Every time I think I'm a bad welder...I'm gonna just look at that photo to make me feel better. Scott has given a good suggestion. Use the engine with the rewelded sprocket until your rebuilt engine is ready and available.

The suggestion I was going to make was to carefully remove the weld & sprocket, and then recut the shaft for a smaller nut, maybe two sizes smaller. So if the OEM nut is an M20 (that's a guses), see if you can cut the shaft for an M16. You'd also have to find a washer with an M16 that has the correct diameter - like a fender washer. A machine shop may have to cut the washer for you.
 

Motogiro

Vrrroooooom!
Staff member
Moderator
Elite Member
Site Supporter
I'm wondering if you could grind it center punch,drill and tap it for a bolt. red thread locker or if there's enough shaft left drill for a wire tie or cotter pin.
 

gnyce

Site Supporter
Soooooooooo.... funny you bring this up. I discovered a few years back that my '87 FZR1000 has the same situation (but a much better weld, I'm pleased to say). To-date I have ignored it, since the front sprocket was still in decent enough shape that I didn't have to address it immediately, but - I really shouldn't put it off too much longer. I recall that @TownsendsFJR1300 - I think on another forum? - addressed something similar so I'm pretty sure he's "seen some sh*t"". I'm encouraged no one is saying to throw it away.
 

TownsendsFJR1300

2007 FZ6
Site Supporter
The welded/loose/falling off sprocket, for me, has only been seen/read about on this forum..
The S1's, I believe had a re-call on it..

The only other MC site I occasionally visit is an FJR site which doesn't have sprockets. :)
 
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