07 YZ450 Louder engine noise then normal?

I have about 5-7 hours on mine and I just started to notice this louder noise when I am in first gear going pretty slow (about 5mph). I am used to the normal rattle noise but now I am hearing an extra rattle just around this speed under a small load and it is definetly louder than it was the last time I rode before this last time when I first starting hearing the noise. It only happens around this speed and load but goes away as soon as I get on it and get out of that area in the rpm range and the small load. Its loud enough to hear with my helmet on and over my exhaust. It sounds like something is loose and making a noticably louder rattle sound so I checked all the bolts around the engine and exhaust and everything was good. It almost sounds like I don't have enough oil if that makes sense (louder valve noises), but I double checked the oil level and all was good. Anybody have any ideas?

If the chain is too loose it will rub on the subframe and it happens to me usually in first gear under low torque so maybe thats what your hearing?

All the 06/07's are noisy. I thought my 06 was in trouble also at 5/7hrs as I was noticing the noise also for the first time.

I solved it by adding a WC skidplate and using the foam element they supply to muffle the noise. The clutches are somewhat noisy too. Pull in the clutch and see if it gets quieter.

Many more hrs later......motor still going strong....noise and all. :thumbsup:

There are many threads on the 06 and 07 engine noise. Mine was so loud, I tore it down just to check it. I found nothing wrong in the bottom or top end of the motor. I put in a new forged piston and shimmed the valves. You should hear it now. It literally sounds to me like it will let go at any time but nothing is wrong with it. One change for 08 was different piston and gear clearances to quiet the noise. It's in the sales brochure that they wanted to quiet the engine down because so many people are convinced they are going to blow up when they hear them. You just have to live with it and believe in it....

Ok thanks guys. I have read the threads and know they are pretty noisy. I have a YFZ450 (pretty much same motor) with probabaly around 80-100 hours on it and still runs great and had a 250f before this bike and they are/were both pretty noisy, but not really like this sound I am hearing. Maybe it just me :crazy: I will check into the skid plate and see. I adjusted my chain slack before this so that is all good to go.

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