standard sprockets from Yamaha???

10 replies to this topic
  • flintlock28

Posted May 03, 2005 - 04:43 PM


I bought my 2004 Yz 450f from a guy with about 50 hours on it. The sprockets both look good and the chain looks pretty decent also. The rear sprocket is a Sunstar 48 teeth, and the chain is marked Japan with DID on it. Are these probably the standard equipment that the bike came with???? or are they probably replacemants that the previous owner put on??? He only trail rode the bike on the 40 acres that he owned. Let me know, thanks.....Don

  • Joe_Jet

Posted May 03, 2005 - 04:47 PM


Those are the stock items and they will last if you lube the chain prior to every moto or every 30" and maintain the tension per the manual.

  • saucebox

Posted May 03, 2005 - 05:00 PM


if he's got 50 hours on that chain its probably junk. my stock chain was/is shot after no time at all. i need a job :)

  • flintlock28

Posted May 03, 2005 - 05:33 PM


Thanks for the help, I do remember the previous owner said that he had to take out two links due to chain stretch. I took off the chain today and cleaned it in a tub of Kerosene, using a worn brush on it, and also on the sprockets. The sprockets showed a little wear on the one edge, but not too much. I than dried the chain and applied Maxima Chain wax. The chain play was within specs. I guess I'll just wait until the chain stretches furthur, and eventually put on Ironman sprockets and a good "o" or"x" chain at some later time. Don

  • sirthumpalot

Posted May 03, 2005 - 05:34 PM


50 hours is impressive on the stock hardware. Either he idled around in circles for 50 hours, or the bike has less time on it than he says. Either way it sounds good for you. :)

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  • yzmotocrossracing

Posted May 03, 2005 - 07:38 PM


I don't know if you had a reply on the sprockets yet but the YZ 450 stock gear is a 14 on the front and a 48 on the rear. I do believe the Chain is stock also. Now it depends what you what to do with the gearing or where your riding but I have messed with these alot. Now if you what speed then lets gear it up we just run Mexico and now you want to talk about speed I but a 15 on the front and a 42 on the rear it will run about 105 MPH. Now if you want it to jump out from under you put a 13 on the front and a 50 or a 52 on the rear. It just depend on what you want to do.

  • DigilubeJay

Posted May 07, 2005 - 04:06 AM


If the guy took out a couple of links due to chain elongation, then your chain is ready to snap. Once a chain is more than 2% of it's original length, it is fair game for failure.
Do not ride with it unless you don't mind a sudden dirt lunch.

114 links x .625" (chain pitch) = 71.25" (new total length)

Taking two links out means that a total of 2.5" was taken out of the chain. (when we remove one link, we are actually removing two reels or 1.25")
2% of 71.25" is 1.425"

So, if 2.5" has been taken out, then the chain is AT LEAST 3.5% longer than original length. And this is best case scenario....your situation is worse because I'm not even taking into account the wear that isn't being used in this figure.

Change chain and sprockets NOW!

  • DigilubeJay

Posted May 07, 2005 - 04:12 AM


50 hours is impressive on the stock hardware. Either he idled around in circles for 50 hours, or the bike has less time on it than he says. Either way it sounds good for you. :)

OR...they guy knew how to properly care for his sprockets and chain.
But from what I've read here, he didn't. I'm very suspect that the guy didn't really practice good maint. because he claimed he removed two links.

BUT...50 hours on stock chains and sprockets is completely reasonable, but only for those who know what they are doing and how to do it.

Those who depend on their equipment taking care of itself will never get much life out of anything less than titanium and kryptonite.

  • flintlock28

Posted May 07, 2005 - 07:13 AM


Thanks for the replies. The guy who owned it before, may have meant 1 link, I'm not sure. I'm going to take the time to measure 10 lengths according to the Yamaha manual and check it out. Don

  • grayracer513

Posted May 07, 2005 - 07:35 AM


When you're measuring for chain stretch, measure several 10 pin sections. You can have one good one in an otherwise bad chain and throw of your results if you just take one.

If you can lift the chain free of the rear sprocket at its rear edge enough to slip a 1/16" or 3/32" drill bit under it, and the sprocket looks fairly normal, the chain is too long, and will quickly wear out your sprockets (if it doesn't break first; OEM YZ chains are prety poor stuff).

  • SureBlue

Posted May 07, 2005 - 10:22 AM


The stock chain will and can never ever last for 50 hours. The previous owner has run a while with them, then replaced them with quality stuff and again put the originals back when selling the bike. That is how I do too.
On a big thumper you can putt around with the stock chain for only about 10 hours, then it is totally stretched and may snap and ruin your case.
Change it now with quality sprockets.

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