Cam shaft caps problem. Help needed.


I'm new in 4 strokes but I have mechanical experience. Today I decided to adjust my valve clearances. They was 0,09 on one intake, 0,17 and 0,19 on exhaust so not bad but the job has to be done. So I removed cams and mesured shims and then I took a look on my cam shaft caps and ..take a look on pictures.

I bought this bike month ago changed the oil and had 4 rides so that's not my fault.

The cams are ideal , bearings to.

Cam seats in cylinder head are ideal to.

Tell me what to do?

What I have to replace?

These scratches aren't deep. On the intake I would say that the surface doesn't look like a mirror that's everything. And on the exhoust I removed this black burnt oil with my finger nail.

pictures don't work

Thanks. Now pictures works

looks OK, but pick up some plasti gages and measure cap to cam clearance to be sure. The bearings on my 04 were way worse and I am still running them with no problems.

The scratching looks very minor, and I'd probably remove them by hand using a ScotchBrite pad. These, if you are not familiar with them, are an abrasive pad resembling steel wool, but made from plastic. The advantage is that they don't shed grit or pieces of wire. If there are none available, use steel wool or fine sandpaper and dress the scratches up just enough to remove the metal that is raised above the original surface. Clean THOROUGHLY and reassemble it.

The cam caps are not replaceable, as they are bolted in place when the cam bores are cut, and they are only available as a part of the head. There are machine shops here that can refinish the cam bores, even if they are rather badly damaged.

As for your valves, you should plan to re-inspect them soon after you adjust them. If your bike is a 2001 or newer, it will have titanium valves. Ti valves are hard enough for the job only because of a hard coating that is applied to the valve face, and the coating is very thin. If the wear that caused your valves to close up is on the valve seat only, you will find that the valves stay at the clearance you set them to for some time. But if the wear is to the valve face, the coating will have failed, and the valves will be tighter than what you set them to very quickly. That will mean that it's time to replace them.

I had the same thing happen when my bike was new(03) only it was really bad and I had to take the head to Engine dynamics in Petaluma CA to have the head

repaired.....Mike said that all the Hondas and Yamahas were coming from the factory with too tight of clearance and extended high rpm use was killing the cam bearings.......


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now