If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

- George Washington

Thursday, 2 June 2011

Chain Reaction

I mentioned that the MoT tester had advisoried me that the drive chain was well buggered on the XT. He was not wrong. Here is one end of the old chain next to the new:

It's a full inch shorter, which translates to about 1.5% of the total length. The manual says the chain is dead when it becomes longer then the original by ... 1.5%. It is sloppy and full of tight spots, so it definitely needed doing.

The gearbox sprocket was badly worn too:

New one on the left, old one on the right. The teeth were getting badly hooked. I'm glad he told me about it when he did, as I don't think I would have given it a proper inspection for a while. After all, it's only 4500 miles since the old one was new.

I have been wondering why the set has only lasted as long as this. Many people get 20-30,000 miles out of a chain, and even with a big thudding single I don't see why it shouldn't have lasted for 15,000 or so. It was lubed every week until I fitted the Scottoiler, although I admit that otherwise it was neglected. As the sprocket is as badly worn as the chain, I don't think I can blame a poor quality chain. (The rear sprocket showed no signs of wear, but then it has three times the number of teeth as the front, so it lives an easier life.)

There's a new set on there now. Let's hope this one lasts a bit better. Some family turned up just as I was finishing off, so I didn't get the chance to give it a test ride. I am looking forward to that, though. The last time I replaced the chain, it was like having a new bike.


  1. Hi Richard, the scottoiler is working well. I didn't get the chance to thank you again for the help, so thanks again. Though I agree that the chain and sprockets should have lasted a lot longer, I've known a lot worse, and in my poor days I'd take off the sprockets and turn them over to get a few more miles. I also could obtain chain off the roll at the local Honda dealers. Ah, the wonders of the split link! I never used the same method as you to gauge wear on the chain. My method was to bend it around, and if it formed one third of a circle it was ready for replacing. The stretch length doesn't matter quite as much since there's plenty of adjustment left and also I've known a new chain to stretch more than a link's length within a couple of weeks. I think the accelerated wear on your parts may be mainly due to them not being original (and very expensive) parts? Patterned parts made by third party manufacturers don't go through the same hardening and tempering processes. Strangely though, years ago I had an off road alloy rear sprocket on a Yamaha SR250 that seemingly couldn't be worn out as long as I kept it properly adjusted.

  2. Are you taking a break? Not heard from you in a while

  3. Anon: thanks, and glad to help. I've replaced the chain now, and it is much improved. The old one was well battered. We shall see how this one lasts. I'm keeping a record, again.

    Bucko: I've had a few days off from blogging. No particular reason, just needed a breather. I'm sure the effluent flow will be back on stream afaore long. Thanks for asking :)

  4. Understandable. Good to see you're not gone though


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