Retarded YZF Timing? Help!

I decided to check the valves on my bike today and was baffled at what I found. It appears to me that someone tried to go in and give it YZF timing. Somewhere during the process they got both cams off by one tooth ending up with EX cam in the stock position and the IN cam 1 tooth retarded. Resulting in what would be retarded YZF timing.

Before I go moving things around I thought it best if I post photos here and ask for opinions.

The bike is a 2000 WR400. I believe it to be stock other than bolt on and free mods like pipe, airbox mod, throttle stop. There ARE tooling marks on the head bolts so for all I know there's a hi-comp piston in there.

The jetting seems fat to me with a 180 main but it runs fine with it. It likes to get hot at slower speeds- more so than other WRs I ride with. I believe retarded cam timing would explain both of those.

Ok.. on to the photos. What should I do from here?

100_2829.jpg

100_2836.jpg

Anyone? Is the timing off or am I dumb?

Solo-WR400

From the photo of the cams I can tell you that the exhaust cam is a YZ cam by the tooth count from the top dot mark to the dot mark on the left. The timing chain pin count between the cams is correct for a YZ setup. The timing marks for the exhaust looks correct at 9:00 and the intake is correct at 3:00. It looks like everything is timed correctly.

Use a pencil to make sure your at T.D.C.

I'm an idiot. I read the manual wrong and freaked out. The cam sprockets are all where they belong.

What's this about it being a YZ cam? Where can I research this to verify it. (I was taught to question sources)

On the bright side I did a leak down test and she's good at 10-15%. Now if I could just figure out why there are tooling marks on the head bolts. Anyone know an easy way to tell what piston is in there?

When I bought my 03 WR 250 I soon afterwards changed out the exhaust cam to a YZ cam. At that time I compared the two cams to see what the differences were. The WR cam had 6-1/2 teeth from the top dot mark to the lower left timing mark, while the YZ cam had 7-1/2 teeth between marks. I don't know if this is published in any of the Yamaha manuals or tech manuals but thats how I know the difference.

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