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Jonbikes

07 yz450 valve check and adjustment

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Bought a used 07 yz450 from a dealer at the beginning of the season and the valves were checked before it left the showroom floor. I've since put around 20-25 hours on the bike. I decided to check the valves the other day and they checked out perfectly within spec so no need to adjust yet but my question is how often do you guys actually check them and how often are you supposed to check them. And should they need to be adjusted, are the pads expensive?

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I have a 06 YZ450 and I checked the valves at 25hrs. No movement. I then checked them again at 100hrs. No movement. I checked them at 150hrs. No movement. I checked them at 200hrs. no movement. I did a rebuild at 246hrs just as a precautionary thing and I shimed my middle intake from a 190 to a 185 I now have 336.5hrs on her and she still runs great on original head. I did change the valve seals when I rebuilt her at 246hrs though. I check them about every 50hrs and the shims are like $5 each but most dealers will swap them straight across.

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+1 40-50 hrs. I had to shim one valve on my 99' after 2 yrs.

Honda shims are in 1/4 sizes too, ex 182 & 187.

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I would worry more about your timing chain $16. Change once a year and check valves then. Bike will start drinking oil and need piston and rings before intake valves start to pancake, check them then.

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Sounds good to me, thanks for the advice guys! I had a pretty good look at the timing chain and it passes the good old visual inspection so far. I was sort of thinking about changing it anyway just to be sure, perhaps if they have one in stock when I go to pick up a tire and some other stuff tonight I will get a timing chain as well since the bike is still half torn apart.

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250+ hours on my '08 and the valves have yet to need adjustment.

I change out the timing chain about every 50 hours, change the oil every 6-10 hours depending on the type of riding I have been doing (Amsoil MCF) and keep a clean air filter on at all times.

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I use the OEM Cam chain from TT store as a replacement. I replace mine every year, which usually amounts to less that 40 hours. The only one I've had show any signs of kinking was the original, otherwise, they have looked fine but for the price, I replace.

BTW, I haven't gone to the trouble to actually measure their stretch because it's so cheap just to replace that darn thing.

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What about smoking. I notice if I rev the bike fairly high in the rpm range with a quick aggressive twist of the throttle in neutral I get a slight grey tinge in the exhaust gasses. It dissipates once it gets about a foot or a bit less from the end of the silencer unlike the smoke you get from a car engine which is burning oil, and it is barely noticeable. It ONLY does this at the upper region of the RPM range and you have to really crank it to load the engine up a touch, if you just slowly roll the throttle on till rev limiter there is no visible exhaust gas. Is this a sign of rings going bad or is it somewhat normal? I'm not even sure you would be able to see it on a video its such little color to the exhaust. The bike has somewhere around 40 hours on it, and only about half that being hard hours.

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I notice if I rev the bike fairly high in the rpm range with a quick aggressive twist of the throttle in neutral I get a slight grey tinge in the exhaust gasses.
Most likely a result of the extra rich mixture produced by the accelerator pump.

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My 06 needed a small adjustment to the intake in 5 years. These yamaha engines are reliable and are not ticking bombs waiting to happen like the 2 smoker crowd like to point out. :ride:

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