Engine noise 450


27 replies to this topic
  • tony_dt

Posted July 09, 2007 - 04:26 AM

#21

I've heard of only a couple of incidents like this. Usually, the cause in earlier YZF's is camshafts partially, or momentarily, seizing in the head. I'd pull the cams and have a look at the journals and saddles, and also check the clearance.

I'm not aware of any issues with stretching chains, or of a tensioner weakness. The tensioner was suspected as a cause of the valve failures in the '06 250F, but the speculators turned out to be wrong about that. YZF tensioners are one of those things that are so simple that they're brilliant. Basically too simple not to work.


Thanks for the input grayracer. I did ask him that. I know that the cam caps are easy to overtighten. He says that he didn't pull them but maybe there is an issue there anyway. I will make sure that he pulls them though. Good thought.

I have never heard of the tensioner going bad on the YZF's but I have seen it happen on the big Kawi's and Zukes. I wasn't sure if something changed on the newere bikes.
Thanks!

  • ben_suhard

Posted July 09, 2007 - 07:11 AM

#22

does anyone have any issues with the motor kinda missing at the top end when it is muggy out? It kinda seems to act like it is hitting a rev limiter, or missing, I also dont have the same power as when it doesnt do it. Mostly noticed in 1st gear.

These bikes do have rev limiters and it will miss and have less power when you hit it 'cause it cuts the ignition(every second spark I think?). Or do you think it's not revving high enough to hit the limiter?

  • ben_suhard

Posted July 09, 2007 - 07:15 AM

#23

This is a 5 valve engine with two cams, these motors often make ticking noises at idle. If the noise gets worst or gets extremely loud when reeving the engine you may want to consider adjusting your valves. Make sure you have oil!

The ticking noises will be quieter if it needs a valve adjust because the gaps are smaller. Hard starting indicates that your valves need adjusting.

  • buzzgrizz

Posted July 09, 2007 - 07:24 AM

#24

what about that noise on a 426 mine does the same thing and it seems to have gotton louder

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  • Justin89

Posted July 14, 2007 - 11:11 AM

#25

I have an 06 yz450f and it is also loud. I also notice that if your bike is off and you hold the kill switch and slowly kick your bike over...you can here some noise too. I'm always afraid that it is going to grenade but that is just me.

  • Quack

Posted July 21, 2007 - 02:43 PM

#26

These bikes do have rev limiters and it will miss and have less power when you hit it 'cause it cuts the ignition(every second spark I think?). Or do you think it's not revving high enough to hit the limiter?


It really didnt seem like it was all the way up there, but maybe it was.

  • grayracer513

Posted July 21, 2007 - 03:43 PM

#27

In regard to the rev limit, there is one thing you could look into. One function of the neutral switch is to lower the rev limit in neutral from the normal 11,500 rpm to somewhere around 7k instead. If the blue wire going to the switch reads as grounded in any gear other than neutral, the switch or the wire itself is faulty, and this will cause a major loss of power and speed.

  • Quack

Posted July 21, 2007 - 05:28 PM

#28

In regard to the rev limit, there is one thing you could look into. One function of the neutral switch is to lower the rev limit in neutral from the normal 11,500 rpm to somewhere around 7k instead. If the blue wire going to the switch reads as grounded in any gear other than neutral, the switch or the wire itself is faulty, and this will cause a major loss of power and speed.


Thanks Gray I will see if I can take a look at this soon.





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