Engine noise

Hi Everyone,

Hopin' yall can help with a concern I have with my '03 WR450.

The engine has quite a loud knocking sound which seems to come from the upper part of the engine.

It's there all the time, ie when hot, cold, idling. If I lean over the handlebars, I can even hear it while riding at low speeds.

After making a few local enquiries, I'm told that these engines are quite noisy and this was quite normal.

I've checked the valve clearances.......... :thumbsup:

Examined the cam lobes and followers..... :lame:

Checked the timing chain and tensioner... :p

Changed the oil using correct spec......... :bonk:

I can't work out for the life of me, where this noise comes from.

I'm pulling the barrel off tomorrow to check the piston.

To all you WR owners out there, are these engines quite knocky or is it just mine.

Other than the noise, the bike's fine.

Any help much appreciated,


Mine doesnt have any major knocks going on in it, Ive put 7200kms on it hard ridding.

How many kms have you got on yours? im wondering if you got piston slap?

they are all loud!!!!!

thin engine walls to save wight!

mine is loud as well

i went to dealers and asked as well they told me it sounded normal

rode several of buddys o3's as well same noise

iv been riding mine for about a year now and still alive

:thumbsup: and :lame:

Yep they are noisy. A bit scary till you get use to it .I have ridden 2 other wr450s and a yzf450 they sound the same as mine. But mine with a alloy bash plate makes a lot more noise. On the last rebuild I did find the small piston pin wasn't flash replaced with the new piston and rings. And the crank bearings were replaced .Still noisy. While i had the motor apart I flicked the bore with my finger it sounds like porcerlain it is very thin. Bike has 6000 km on it now still going great. :thumbsup:

Thanks for the replies so far guys.

My bike's done around 6-7000 km I guess.

I've removed the cylinder and piston now. The cylinder is in perfect condition but the piston is confusing me. :thumbsup:

If I measure the piston near the bottom of the skirt, its on spec at 95.00mm......

but if I measure it near the top, it appears tapered, and measures 94.60mm.

Is this wear or are they meant to be tapered?

If it is wear, maybe I am hearing piston slap.

If the piston is normal.......

Your thoughts guys..........


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