Adjusting valves

[JohnChilders]

First off, I do not own a manual yet. My valves are in need of adjusting my friend says. They click loud and fast. Twice as fast as the exhaust. How hard is it to fix this? What all would I have to do? I have a 2000 300ex. Thanks in advance for any help.

[wilkin250r]

I think I can walk you through this without a manual. The valves themselves are not difficult, but you have to remove all the stuff in the way, like the fenders and gas tank. You'll also need to have your engine at Top Dead Center. This ensures your valves are totally closed, and there's no tension on them. You can't adjust them while they're open.

Read this article here "400EX valve adjustment (http://www.exriders.com/techarticles/valves.html) " and pay special attention to the last few pictures. The 300EX will look slightly different, but the basic method is the same, they adjust the same way. (most of the article describes how to remove the fenders, so ignore that part)

The last picture of the article looks like this, and the 300EX is really similar, except you'll see two of them, and it won't have the slot on the top for a flathead screwdriver.

http://www.exriders.com/techarticles/images/fig_10.jpg

As for special tools, you'll need a flat feeler gauge 0.004 inch, like the one shown in the picture, and the smallest adjustable wrench you can find, because like I said, the 300EX won't have the slot on the top for a screwdriver, so you'll need a wrench on it. I think it's 4mm.

Always adjust valves when the engine is cold, not because of safety, but because you're compensating for heat expansion. If you adjust while it's hot, or even warm, they won't be adjusted properly.

Start by setting your engine to Top Dead Center, it's going to be similar to the method described in the article. (don't worry, it actually doesn't have to be exact, but you need it close).

Remove the fenders and gas tank, I don't think you'll need a manual for this. That will give you nearly unrestricted access to the top of the engine.

The top of the 300EX doesn't look quite the same as the 400EX. You should see two oval covers on top of the engine, each held on with two bolts.

Under those covers, you should see something that looks similar to the photo, only there will be two of them. These are your valve lash adjustments. Basically an adjusting nut (that's your little 4mm guy) and a locknut (10mm). The adjustment should be evident by now, you loosen the locknut, turn the inner screw to adjust, and then tighten the locknut down. It's actually fairly simple.

For your first time, you might want to remove both covers (keep them organized so you don't mix them up) and put the feeler gauge in between just like it's shown in the picture, before any adjustment. If you can't even get a 0.002 feeler in there, then you're not at Top Dead Center. It means you're pushing on the valve. It's safe to rotate the engine to TDC without putting it all back together, but be sure not to knock any dirt into those openings.

Loosen the locknut, (pay attention to the aproximate amount of torque on that nut) and adjust the inner screw in or out until there is a slight drag on the feeler guage. Tighten the locknut while holding the adjuster screw (because otherwise it will move). After tightening, recheck the clearance to make sure it's still the same, you should feel a slight drag on the 0.004 feeler gauge.

Both intake and exhaust are set at 0.004 inches, and reassemble (make sure not to over-torque those little bolts on the valve covers.)