Not Your Typical Valve Question, I think...

So I got a 2002 426 yesterday, motor runs GREAT and sounds good! But anyways I opened it up and checked the valves just to see if they needed adjustment...

The previous owner has owned for 5 years and never did any work on it besides changing the oil and cleaning the filter. He only rode it 7 times (so he probably didnt need to do anything) and I beleive him, this thing Is clean! It has evidence of sitting in a garage for years! alot of gunk in the carb and stuff like that.

Just FYI the first owner was a Vet Class Racer, but didnt ever rebuild it (I knew the original owner)...

Anyways knowing that he didnt do any maintenance, I went about checking the valves, THEY WERE PERFECT both of the exhaust valves measured .22mm and the intake .14mm. So for a bike that is 9 years old is this normal? cam chain looks terrific too! idk Ive never seen a bike that has ever looked this good after this long...

If he only rode it 7 times, it doesn't matter how old it is.

For Yamaha four strokes, yes, this is normal. I just had to adjust the valves for the first time ever on my 2006 WR450 and I put a decent amount of miles on it every year. They were only .001mm out of spec too!

They were only .001mm out of spec too!
Be careful with your decimals, there....
If he only rode it 7 times, it doesn't matter how old it is.

The owner before him was a Vet class racer, I knew the first owner. He probably put about 200-250 hours on it. Ive just always heard that, "You need to adjust the vavles on these things and replace the cam chain every 60 hours" so I always assumed this meant your motor would be out of spec every 60 hours, not that It could be fine forever. (Now that might sound confusing, I have problems getting my thoughts to match the English language:thumbsup:, no im not foreign either...)

Now that thats clear as mud...

That's different. Still, not all that unusual for a YZF. The '03 I had before my current bike had well over 400 hours on it and never had a thing done other than oil changes and an annual cam chain.

That's different. Still, not all that unusual for a YZF. The '03 I had before my current bike had well over 400 hours on it and never had a thing done other than oil changes and an annual cam chain.

Man, Im hoping to have some luck like that!

Ok I got a question about that "annual cam chain" replacement... Why do you need to change the cam chain? Does it stretch out or get brittle?

JW I like to have an answer to back up my maintenance!

They do stretch, although chains don't literally stretch in the plastic sense. What happens is the pivot point wear, both at the pins and at the holes in the plates. The collective wear of all those pins makes the chain longer than it should be, and more importantly, makes it the wrong pitch for the sprockets it runs over. With roller chains, that leads to hooked or "pulled over" teeth on the sprockets. With Morse type chains like timing chains, it causes the plates to become staggered so that only half the plates bear on the driving surface of the sprocket teeth, and that leads to wear on the sprockets. Since replacing the sprocket on the crank of a YZF means replacing the entire crank, well, it's undesirable.

The other thing that happens occasionally is that the chain will develop tight, binding links as a result of plate galling and/or "balling up" debris from the oil. These stiffened links will fool the tensioner until one day when the engine kicks back or something else causes a bunch of them to pull out straight and the engine suddenly skips time and wipes out the head and top end. Also undesirable.

They do stretch, although chains don't literally stretch in the plastic sense. What happens is the pivot point wear, both at the pins and at the holes in the plates. The collective wear of all those pins makes the chain longer than it should be, and more importantly, makes it the wrong pitch for the sprockets it runs over. With roller chains, that leads to hooked or "pulled over" teeth on the sprockets. With Morse type chains like timing chains, it causes the plates to become staggered so that only half the plates bear on the driving surface of the sprocket teeth, and that leads to wear on the sprockets. Since replacing the sprocket on the crank of a YZF means replacing the entire crank, well, it's undesirable.

The other thing that happens occasionally is that the chain will develop tight, binding links as a result of plate galling and/or "balling up" debris from the oil. These stiffened links will fool the tensioner until one day when the engine kicks back or something else causes a bunch of them to pull out straight and the engine suddenly skips time and wipes out the head and top end. Also undesirable.

Thanks Dude!

Thats the answer I was suspecting, very thorough I appreciate your time!

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