426 Engine Noise...


39 replies to this topic
  • creeker

Posted August 02, 2007 - 03:53 PM

#1

Just installed a 450 Cam in the 00' 426 I picked up a few months back and now it has a loud "tapping" sound.

Bike starts on the first kick, but it sounds like the valves are tapping or something. I can hear the noise at idle and it gets louder if I rev it at all.

The clearances are on the tight side, could this be my problem?

I also installed a new cam chain.

  • 642MX

Posted August 02, 2007 - 05:32 PM

#2

Typically tight valves are quiet. Loose valves are noisy. Where is the tapping coming from? Put a long screw driver up to your ear and take a listen. Try to track down the source and post back.

  • creeker

Posted August 02, 2007 - 05:35 PM

#3

The tapping sounds as if it is coming from the Left Side of the engine and it seems to be more noticeable around the head area rather than the Valve cover area.

  • 642MX

Posted August 02, 2007 - 05:53 PM

#4

The tapping sounds as if it is coming from the Left Side of the engine around the valve area.


Are you sure that the cam isn't in a bind? Its easy to do. I'd pull the valve cover and double check everything.

  • creeker

Posted August 02, 2007 - 06:27 PM

#5

I have pulled the head checked everything out and all appears to be well, but I will check again. I can't think of anything else it could be other than a bent valve...

  • 642MX

Posted August 02, 2007 - 06:32 PM

#6

I have pulled the head checked everything out and all appears to be well, but I will check again. I can't think of anything else it could be other than a bent valve...


While your in there checking things out, go ahead and set the valve clearance to the middle of the spec.

What makes you think it has a bent valve? Did you try to time it with the marks on the 450 cam?

  • creeker

Posted August 02, 2007 - 06:39 PM

#7

Well, originally I thought I had it timed properly and I kicked it over a couple of times and the bike didn't start. So, I took valve cover off and I noticed immediately I had it two pins off. I then set the timing correctly and kicked it and it started first crank, but then had the tapping noise. :crazy:

Could I have bent the valves?

  • 642MX

Posted August 02, 2007 - 06:43 PM

#8

Anythings possible, but I don't think it would be so willing to start with a bent valve. If the valve was bent, the compression would be low from it not sealing and it would be hard to start.

  • creeker

Posted August 02, 2007 - 07:02 PM

#9

I can't imagine that's it, but who knows. It starts first crank with no problems and it actually pretty smooth when kicking through.

Maybe the cam is just in a bind like you said, I will tear back into and double check everything once again.

Thanks!

  • crazyal426

Posted August 02, 2007 - 07:06 PM

#10

The cam stuff may or may not be related. I chased a noise in my 2000 426 for several years replacing cam chain, tensioner, clutch stuff, piston pin and other stuff. I got so fed up with noise I let it go. I figured if it was bad enough, it will break and really show where it was coming from. Turned out, after some time my crank went and I discovered the source of the knocking, it was not the crank. The primary drive gear nut on the right side of the crank had loosened up. The folding lock washer had not been folded over from the factory and allowed the nut to back off just a little bit and give the gears that run the oil pump and the clutch basket a little slop. The square keyway had almost sheared and I spun the nut off with my fingers, nevermind the 54 ft lbs required torque. If your cam swap did not start making noise right away, I would not bet that the problem is in your valvetrain. If my engine was not put together right from the factory there is a good chance there is another 426 out there with the same problem. Good luck.:thumbsup:

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  • creeker

Posted August 02, 2007 - 07:11 PM

#11

The engine never made the first noise until after the cam/cam chain install. That is what concerns me so... but thanks for the info!

  • creeker

Posted August 05, 2007 - 03:49 PM

#12

Okay... took the valve cover back off and checked everything out again. The only thing I notice at all that seems odd is that the chain doesn't fit nearly a snug on the new exhaust cam as it does the stock intake cam. Is this normal???

  • 642MX

Posted August 05, 2007 - 03:53 PM

#13

The only thing I notice at all that seems odd is that the chain doesn't fit nearly a snug on the new exhaust cam as it does the stock intake cam. Is this normal???


Yes, its normal. The 450 cam gear is a little different compared to the 426 gear. It doesn't hurt anything, but it does look odd.

Maybe the noise your hearing is just the way it sounds. I'd ride it around a little bit and then change the oil. Make sure the oil and filter look okay before you beat on it.

  • creeker

Posted August 05, 2007 - 03:56 PM

#14

That is what I am thinking too. So far I have only started it on the stand and tried to figure out what the heck the noise is... haven't actually rode it any. I just can't figure out what it could possibly be, everything looks perfect.

  • 642MX

Posted August 05, 2007 - 04:02 PM

#15

That is what I am thinking too. So far I have only started it on the stand and tried to figure out what the heck the noise is... haven't actually rode it any. I just can't figure out what it could possibly be, everything looks perfect.


It could be a classic "I did the work myself, but not sure it I did it right....... and now there is a noise" type of thing. :ride:

I've been there myself. The first time I rebuilt the top end of my 426 I didn't want to start it. And when I did, it had a noise in it, but the noise was just a little Wiseco piston slap. :prof:

Ride it a little bit. Its probably okay. :thumbsup:

  • creeker

Posted August 05, 2007 - 05:00 PM

#16

I hope you are right! :crazy:

The Wiseco High Comp is next on my list of things to do... THanks!

  • Fastest1

Posted August 06, 2007 - 05:24 AM

#17

What year is the motor? If it is a 2000 it sounds like a key on the counter balancer gear. If it is worn it will knock. If it is neglected it can cause some chaos.

  • creeker

Posted August 06, 2007 - 11:14 AM

#18

The motor is a 2000 model, but the noise wasn't there until AFTER the cam and cam chain install...

  • Fastest1

Posted August 07, 2007 - 04:55 PM

#19

Though I have heard noises also after changing something, I would look into the keyway problem if you have never checked it. It is prone to failure and in 2001 they went to a splined shaft instead. I just had Falicon balance 1 of mine and put a right side of a 2001 crank on it. You will just need a new key ($2.00 or so) and an hour or 2 of your time. It will give you peace of mind! If it is the problem and you neglect it, it could cause damage to the end of the crank and possibly more.

  • Gerry B

Posted August 07, 2007 - 09:21 PM

#20

Fastest1 has it right. I'll guarantee that is the problem. The 2000 YZ426's had a key on the counter balancer gear. They got rid of it in 01 and went to splines. I quarantee you take the side cover off on the clutch side and you will see that key pretty much messed up and possibly the gear also. The reason I know this is because it happened to me. It's a very common problem with the 2000 YZ426. I'll bet money on this!





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