WR450 06 Cam chain noise?

Im a newby to this site. I was wondering if you guys can help me. I seem to have a random rattle from around the cylinder head area of my 06 WR450F.It only happens on part throttle load. It`s quiet(ish) on tickover and the noise dissapears if I nail it hard. I have only just bought this bike 2nd hand. Its always done this. The bike starts really easy and goes like stink when nailed.

So far i`ve pulled the left side generator cover off. All seams well. And i`ve also removed the cam chain tensioner and checked that it winds back by itself under spring tension...all is well. I`ve pulled the cam cover off and checked the cam chain. It looks tight - even when kicked over slowly. So i`m stuck. Is it possible that the tensioner can wind back under certain conditions. Also is it common for the camchain to wear on this bike? And lastly can anyone recomend an online supplier of camchains/tensioners here in the UK. Sorry for the long post.

these bikes are noisy , im surprised thats all your hearing . lots of thin lightweight alloys . pretty much the nature of the beast i would not worry about it .

Hi, the noise from the motor on the WR's is a bit frightening. I came from a DR-Z that I knew was about to blow, and the Yam sounds nearly as bad. Like you, I've pulled the tensioner, checked everything there is to check, and all is well. I really do think it's the nature of the beast - they are noisy! I've checked with a couple of other WR's and they all seem to sound the same.

There is a rattle at light loads/ mid revs thats sounds just like a camchain that's too loose, I think it's a case of get used to it.....

To be honest, I think it's piston slap. They have a very short skirt and a high compression ratio, and are not designed for gentle running or for noise regs. It's a lot of power to get out of a small(ish) engine and noise is a by-product.

Do you know how many hours are on the bike - one thing that is important is to replace the cam chain any time you do anything to the top end (Rings/valves/piston - maybe every 75-100 hours)

next time you check your valve shim gap, take the cam chain tensioner off and lift the chain between the cams, if there is a lot of play, I would say it's time to replace it, when installing a cam chain, a new chain fits VERY tight even without the tensioner.

I've had an 03 and 07wr 450,both were noisy but never let me down.Brad's right between the thin,light engine castings and the high power output some mechanical noise is the trade off.

Is it possible that you are just hearing the drive chain?

Thanks for the replies guys. I don`t think its the final drive chain -too high up in the engine. I use this bike on the road so I sometimes do need to go part throttle. I`m a car spanner man by trade and it still dont sound right to me. So I think i`m gonna get a cam chain and throw that in. Also, i forgot to mention in the 1st post, it backfires like mad on over run through the Leo Vice X3 pipe...i`m not so bothered about this but wounded if the 2 symptoms where linked. I`l post the results on the cam chain swop when i`ve done it.

:bonk: Well guys, it appears im a bit too over enthuiastic with the spanners. I feel such a fool. Crispy1207 was right. Tightened the final drive chain and the noise dissapeared. :bonk: Thanks again for your imputs lads :bonk: :bonk: :bonk:

Backfires like mad?

Is the AIS removed or are you on the stock jetting?

Yeah the AIS is remove. Was`nt on the bike when I bought it 2nd hand. Dont know what jetting is fitted as I have not removed the carb as yet. The tickover speed is a bit up and down so me thinks the jetting is the next thing i`m gonna look at. I can live with the backfiring on overrun really. Don`t know if my neighbours can though:ride: :bonk: :bonk: :bonk:

Backfiring makes piston and valves very unhappy...

Now if its just a little "popping" when you decelerate thats not a big deal but if you are backfiring on the gas you need to get that sorted ASAP!

Could be the ACV (air cut valve) on the left side of the carb was disabled by the previous owner which causes popping on decel. Its easy to access while on the bike. Search ACV valve mods on thins sight.

My Wr450 03' has the exact same problem. But when you say Final Drive Chain.... do you mean the chain that drives the rear wheel? Or some other chain

If it is the chain that drives the rear wheel where abouts did u tighten up?

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