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blue9red9

Last word on engine noise

12 posts in this topic

I noticed a thread a couple days ago... more on engine noise. My used 06 yz450 bothered me so much with the noise, I tore it down. New piston, rings, valves were at the tight end of good so I shimmed them back up to the fat end. Bottom end was tight. After putting it back together, it starts faster and runs just as good as ever. But it's making more of the tapping noise now at idle than ever. Goes away off idle. So the guy who said the valves being shimmed would make more noise, I hope he was right. I don't have the stomach for such a loud racket coming from my engine. I've been around this stuff for decades and I can't believe yamaha let the engine go out the door making that racket. I love the bike though.

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They are noisy as hell. One thing for sure about these new 4 strokes is they are hard to judge problems by engine noise.

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My used 06 yz450 bothered me so much with the noise, I tore it down. New piston, rings,

You didn't happen to install a Wiseco piston?

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I noticed a thread a couple days ago... more on engine noise. My used 06 yz450 bothered me so much with the noise, I tore it down. New piston, rings, valves were at the tight end of good so I shimmed them back up to the fat end. Bottom end was tight. After putting it back together, it starts faster and runs just as good as ever. But it's making more of the tapping noise now at idle than ever. Goes away off idle. So the guy who said the valves being shimmed would make more noise, I hope he was right. I don't have the stomach for such a loud racket coming from my engine. I've been around this stuff for decades and I can't believe yamaha let the engine go out the door making that racket. I love the bike though.

My bike got louder after i shimmed the valves.Still runs great.I even tried putting foam between the skid plate and the frame and its still ticks to death.I think next time i go riding i'm going with earplugs.:thumbsup:

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Although the noise does bother me, i can deal with it as long as the noise is not implicit of wear, poor design, cheap components, defects, failure, etc. Id rather have a motor that ticks and clanks for four years than a quiet motor that runs for 6 months!

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I did install a Wiseco piston. Why?

Wiseco's are forged and require more cylinder to piston clearance than the stock cast piston.

I have a Wiseco in my bike and the piston slap is a lot louder than stock, but its normal. :thumbsup:

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What happens when I go to sell this thing in another year or so and it's making all this damned racket. I get 2 minutes of quiet (relative term) until the oil warms up then nobody in their right mind would buy something that sounds like that. Looks like it's a keeper.

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That's partly true. Wisecos do fit looser, and they do slap because of it. It also used to be that this was categorically true of all forged pistons, but processes have improved to allow the use of more silicon in alloys for forging.

Silicon is added to aluminum to reduce its thermal expansion so that less clearance is needed in fitting an aluminum piston to a lesser expanding iron bore. But adding silicon used to make the metal too hard to be forged without cracking. That has changed. The last set of TRW forged pistons I used in a Chevy small block were fit at .002".

Another point is that the bore isn't iron or steel in a YZF, anyway, so in the end, there's little real reason for the loose fit of Wisecos other than it's how they choose to do it, and possibly the use of an older process or alloy.

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What happens when I go to sell this thing in another year or so and it's making all this damned racket. I get 2 minutes of quiet (relative term) until the oil warms up then nobody in their right mind would buy something that sounds like that. Looks like it's a keeper.

Show the potential buyer the invoice for the piston and tell them that it makes more noise and explain why. Or print this page and show it to them. :thumbsup:

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