need help with motor noise

[73watermutt]

I just looked at a pretty clean '07 YFZ and I noticed a faint sound when I reved it up kinda like a car fan belt squeak or similar noise. Anyone know that that could be? The quad is clean with little tire wear but that noise is putting me off.

[Pack]

Maybe it's your valves. They say you need them set after it's broke in, or when they start making noise. That's what it sounds like to me.

[73watermutt]

I was told it could also be a rod bearing?

[Pack]

If it was a rod bearing, it'd be more like a metal against metal knocking noise, rather than the noise you described.

[squadie]

When I did the exhaust cam mod the timing chain guide got out of position. When I revved the engine it made a high pitched metal squeaking sound. Was the sound of the timing chain rubbing against other metal -- unfortunately...

[73watermutt]

The seller said it does not have the cam mod. It does have an FMF exhaust but that's it. It is just a faint squeak only when reved a bit. It sounds just like a squeaky fan belt. I was interested in this quad but I looked at another YFZ with the same squeak but alot louder and was told it could be the rod bearing so that is why I was thinking that.

[73watermutt]

Maybe this is just a YFZ thing? I have been looking at alot of YFZ's and all of them have this sound when reving up with some being louder than others.

[XcYFZRacer]

I am on my 3rd YFZ 05, 06, and 08 and they have all had motor noises but never a failure. Most if not all YFZ owners will tell you their motor makes noises that cant always be explained, and I am sure this holds true with other manufactures High Rev 450 engines.

[BrettOaktree]

does he have the airbox lid off, because on my yfz if you take the seat off and rev it and just listen u can hear a similar sound from it sucking air, i can also notice it when riding. it may sound stupid but that would be my guess.

[Toadz400]

Originally posted by BrettOaktree
does he have the airbox lid off, because on my yfz if you take the seat off and rev it and just listen u can hear a similar sound from it sucking air, i can also notice it when riding. it may sound stupid but that would be my guess.

YFZ's do make some very peculiar noises. With the air box lid off you will hear an odd, higher pitched noise when hitting the throttle.

Pack- whoever "they" is that is telling you that you need to "set" your valves after break-in, I suggest not paying attention to them.

[Pack]

Originally posted by Toadz400
YFZ's do make some very peculiar noises. With the air box lid off you will hear an odd, higher pitched noise when hitting the throttle.

Pack- whoever "they" is that is telling you that you need to "set" your valves after break-in, I suggest not paying attention to them.
I have an '07 that I bought brand new out of the crate, and haven't set my valves yet. "They" were the ones at the dealer and a few other mechanics that I'm sure were just trying to get some easy money from me. When I looked more into it, I figured I'll get it done when they start making noise.

But thanks anyway.

[XcYFZRacer]

The only problem with not taking 1/2 an hour to atleast check your valve clearences is with these types of motors the valves don't get loose, as they will only get tighter, and if they get to tight bad things happen quickly.

[JR3]

im on a built motor and yes very noisy motors these are

[Toadz400]

Originally posted by Pack
I have an '07 that I bought brand new out of the crate, and haven't set my valves yet. "They" were the ones at the dealer and a few other mechanics that I'm sure were just trying to get some easy money from me. When I looked more into it, I figured I'll get it done when they start making noise.

But thanks anyway.

I would definitely not listen to them then. You can not simply adjust the valves like you can on a 400EX. These are shim valves that require measuring and using the correct shims to put them in the right clearance.

It is easy to check them though. Check out the link at YFZCentral. I would check them probably every 10-15 hours if you want to be on the safe side. I've got at least 200+ hours if not much, much more on my all stock '05 engine and my valves are still within spec.

[YFZLOVER07]

it sounds like u need a valve set done asap cuz i never did one on my 07 till about 4 months after break in and it sounded like that and it might be the pipe not sealing on the head all the way so when u rev it up it has blow by