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Can't remove sprockets on my vtr250

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by AndyJ, Sep 30, 2008.

  1. I tried searching, but nothing came up.

    I'm trying to remove the front and rear sprocket on a vtr250. The rear sprocket, connected to the wheel, is held on by allen key bolts. I tried removing these bolts, but they are on so tight that I ended up twisting the allen key out of shape -> now I need a new allen key :oops: And the bolts are no less tight :cry:

    Any ideas?



    The other issue is of course the front sprocket. It's got a centre bolt through the gearbox counter-shaft. When I try to turn the bolt loose it just turns the engine over, yes it's in gear. Do I jam something in between the sprocket teeth to stop it turning? Should I use WD40 or something?

    Was hoping to finish the change before the better half comes home and sees her bike in bits at week's end.
     
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  2. Yes. I few links of chain folded up ususally does the job, but make sure it's placed in a meaty bit of the casting.

    As for the rear, I'm not sure if there is a "trick" with this bike. Some bikes have folded tab washers, but I would have though you would have noticed those. It may be you need to get a lever arm going and bump them, but make sure there is no "trick" first.
     
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  3. 1st up, heat kills loctite, so if you suspect it has been threadlocked (as the rear definitely should have been) give it a lick with a torch before you go stripping the heads and compounding your problems. Impact driver also helps if it's really tight.

    Are there nuts on the back of the sprocket? Easier to undo these ones if that's the case.

    C/S Sprocket: leave the chain on, put the bike top gear, and have a mate put their foot on the brake. You can do this yourself but you'll feel like a goose after you fall arse over with the bike on top of you when the nut breaks loose. :LOL:
     
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  4. Words of experience there Devotard? :LOL:

    +1 on heat to kill loctite. If you don't have a torch, you can improvise all sorts of ways. Heat your hex key on the stove, holding the other end with pliers, then when it's nice and hot, stick it in the bolt and leave it there for 5 minutes.
     
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  5. Great suggestion, only one problem, I have an electric stove here :( hang on, I'll see if the bbq still works, it's been years though.
     
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  6. Hang on there. Any heat should be local to the bolt only. You don't want to wreck any seals etc.

    Locktite have a new product which freezes the bolt and breaks the bond (I haven't used it but the theory is sound). Maybe get a can of that if you don't have an Oxy set.
     
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  7. If you can cool the bolt significantly like that it's likely to make it shrink a bit too and loosen...

    But +1 on leaving the chain on to undo the front sprocket (may be too late for you by the sound of it without back-tracking a long way). You can apparently also stick a 2x4 between the (alloy) spokes of the back and position it in a good place on the swingarm if you're trying to do the job alone.
     
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  8. A tie down strap also works, and less likely to mark things. I've had to do this when removing the clutch cover means removing the brake lever, ergo no rear brake.

    All this because I don't have a rattle gun, which I guess should also really be included in the suggestions.
     
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  9. A length of coat hanger wire tied between the top and bottom runs of the chain can also do the job.
     
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  10. where in melbourne are you? somebody could probably give you a chop out with the right tools.
     
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  11. As an alternative to heat, :
    - spray the bolts with penetrine ( better than WD in this situation).
    - 'shock' the bolts with a hammer and drift ( don't damage the hex )
    - spray with a freezing agent ( Liquid Nitrogen ) they sell that stuff in a can at most Repco & Burson Stores.
    - Then try undoing them ( use something to give you a little leverage )
     
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