2010 valve adjustment discoveries!!!

I was checking my valves tonight to see if I needed to do an adjustment or not. The bike is a month and a half old with 24 hours on the engine.

I ride woods with a lot of low-mid RPM lugging (this engine is all about low end torque, high RPMs are rarely used) through all kinds of mud, dirt etc.

For the first ten hours of the bikes life I was overly religious about oil changes and filter changes, changing the oil every 2 hours and the filter with it!

In the end it was just costing me a bit to much money in oil filters so after the ten hour mark I followed a new schedule.

Every 3 hours an oil change, and every 3rd oil change a new filter. I also always warm the bike up to about 85-90 degrees before I drain to get all the crap suspended so it comes out with the oil instead of sitting in the cases etc.

Pulled the tank and found that you don't have to worry about fuel spilling anywhere cause the pump blocks fuel flow when it's off. Pulled the plastic cover and then removed the plug and set the engine to TDC through the peep hole on the stator cover.

Pulled the valve cover and found that the factory used sealant right near the camshaft gears on the left side of the head. This might explain why my valve cover gasket doesn't like like 50% of the other owners on here. They might be starting to do this with the later production models to solve the oil leaking issue...

Point being the bike was brand new and no one but me has taken it apart, so the sealant is def from the factory. It was only on the left side of the cover, no where else.

Checked my valves and they were perfect, intake was .1mm and the exhaust was .2mm, couldn't fit the .15/.25 gauges in...

Found out that the breather tube DOES ALLOW DIRT INTO THE ENGINE.

Yes, it does, here are pics for proof!


You can see the dirt specs/clumps here as well in the cover


I noticed that the breather is isolated from the camshafts and directs the air underneath to where the oil goes back to the stator. Maybe Yamaha knows that a small amount of dirt makes it through the breather and instead of the dirt dumping onto the cams, it's collected to the return line. From there I'm not to sure where it goes, but the cams are most likely really really sensitive to any dirt. If the dirt is directed away from them and collected to the return, then it should go back to the sump and then to the filter and stopped there.

Not to sure if it goes to the bearings in the tranny/crank first before then though.. probably does...

THe breather by design and hose length shouldn't let any dirt in, but it does at some point. Maybe when your starting the bike in dust conditions, I don't know, but it's not 100% contaminant proof.

Installing a high flow filter might not be such a bad idea...

Wow thanks for the heads up and info. My boy has a '10. But he doesn't get on it hard enough to have to go into the valves yet. But, I'll keep my eyes peeled.

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