engine noise?

19 replies to this topic
  • Shane_Bettin

Posted October 09, 2004 - 05:36 PM


my yz400f motor is really noisy. theres a ticking noise coming from the lower right side of the engine. is there some kind of key or somethin down there thats loose. or is gonna blow up. theres 85 hours on the engine.
thanks shane

  • YZ250F_Rider

Posted October 09, 2004 - 08:02 PM


check the end of this thread.


  • Shane_Bettin

Posted October 10, 2004 - 10:30 AM


which side is it on just so i know exactly what im looken for. i don't know what this key looks like or anything but in the manuel theres small piece thats called the straight key on the right side, is that it. looks like it could be a [@#$%&*!] to replace. also what goes wrong with the key that it makes so much damn noise. does it have to be replaced or just tighened up some how. the shop is closed for the next few days so i can't get one. the bike won't blow up or anything if this key is a little worn will it, i was planning on riding all day today and tommorrow.

  • YZ250F_Rider

Posted October 10, 2004 - 10:32 AM


I believe it's on the same side as you are talking about, the waterpump side.

  • Fastest1

Posted October 10, 2004 - 12:39 PM


Pull the opposite side cover (left) there is a counterbalancer in view once you remove it. See if you can rock it by hand. If you can your key is notched.

  • Shane_Bettin

Posted October 10, 2004 - 06:15 PM


alright ill check it out. so if its notched then i gotta pull the right side cover and replace the key, right?

  • Fastest1

Posted October 10, 2004 - 07:02 PM


You will have to remove the clutch basket, hub and pressure plate. Then remove the nut on the end of the crank, slide off one splined gear and then the keyed gear, the key will fall out of the crank. Order a few while you are at it, or go to Sears I hear they have quite a wide variety of key stock.

  • Shane_Bettin

Posted October 10, 2004 - 07:24 PM


alright so i took the cover off, the balancer can be moved back and forth about 1mm. and as i moves i can here a knock everytime. so i guess that means that i need a new key. anyone know if any damage can happen if i ride with the key worn. haha never thought sears would carry somethin like that. anyway, thanks

  • Fastest1

Posted October 11, 2004 - 04:10 AM


You might be able to ride with it worn, I did for about a year, but if it breaks problems could occur. The keys from Sears might have to be sanded down to fit. They are like .97 from Yamaha. It shouldnt take but about an hour to change it. It will be alot quieter!

  • Shane_Bettin

Posted October 11, 2004 - 11:39 AM


ok right on. holy [@#$%&*!], a years a long time. hasn't been that long at all for me, couple months maybe. i guess ill just have to take that chance for today. thanks

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  • Shane_Bettin

Posted October 12, 2004 - 08:11 PM


well i pulled the right side cover today and turns out that knocking i heard from the other side was just the gear when they make contact as i rock the balancer. what else is down there that it could be. im really hopen its not the crank bearing. what kind of bearing is it, like a roller bearing. it has seamed to have gotten a little louder to with in the last ride as well.

  • Fastest1

Posted October 12, 2004 - 10:28 PM


Have you pulled out the clutch basket and the crank nut and gears to see the key? Yes the gears do have a bit of lash , but the noise is the key.

  • Shane_Bettin

Posted October 13, 2004 - 04:39 PM


no i haven't. i don't have the tool for holding the hub and the basket yet and i don't have any aluminum either.

  • Shane_Bettin

Posted October 15, 2004 - 06:42 PM


i got the basket and gears off. the key isn't worn at all, same as the new one. when i move the gear even with new one the play is in between the crank shaft slot and the key. the key fits tight in the gear. i really hope thats not the problem, anything else it could be.

  • Fastest1

Posted October 16, 2004 - 05:15 AM


Is the keyway in the crank worn? It should fit in the gear and the crank with no play. It is amazing what a couple of thousand RPM's can do to amplify noise. It could be many other things, rod? main bearing? timing chain?

  • Shane_Bettin

Posted October 16, 2004 - 04:18 PM


ya i guess the crank is worn then. it doesn't look it but theres play there. this &%$#@!en sucks. how the hell does it do that, ive only got 80 hours on it. anyone know the price on a crank, stock or after market, some kind of rebuild?. could i just put it back together and ride it, the crank wil probably just wear more, right. that pissed me right off.


Posted October 16, 2004 - 04:40 PM


If I were you I would just ride it and ignore the noise unless it gets worse.

  • Fastest1

Posted October 16, 2004 - 04:55 PM


You could actually buy the right side of a 2001 crank and the counter balancer gear for a splined crank and be cured forever. Or since you know the key isnt ready to break, put it back together and ride it. Just check it every now and then. Fix it when the replacement of the key wont work anymore.

  • Shane_Bettin

Posted October 16, 2004 - 07:16 PM


ok right on. im assuming the cranks are the same for 400 and 426? ill probably just put it back together for the winter. thanks

  • Fastest1

Posted October 17, 2004 - 10:52 AM


I forgot it was a 400, I dont know about the crank parts compatibility. I know the 2000 will accept the 2001 right side.

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