Broken exhaust rocker arm.

Yesterday we were out and about on the trails. About and hour into the ride my '03 started to make a very loud noise from the top-end. The noise increased/decreased with RPM. Shut the bike off immediately so see if there was an obvious issues, (loose exhaust etc...) Nothing obvious. Did a "quick" check to see if a tappet locknut came loose; nope not that.

Removed the valve cover today to find that the exhaust rocker shaft has fractured. I installed new intake and exhaust rocker arms, bearing etc... about 5 rides or so ago. When I installed them, I made sure so measure the play with a feeler gauge.

exhaust rocker shaft

DaleEO said:

kzoo said:

. When I installed them, I made sure so measure the play with a feeler gauge.

exhaust rocker shaft

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Just so I'm clear on what you set with the feeler gauge, did you set the axial play on the arm, or the lash from the adjuster to the valve stem?

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Both.... When I installed the rocker arm I set the axial play, and when I set the lash I used a feeler gauge. The feel on the tappets were new so there shouldn't have been issues with dished feet etc...

steve said:

Oil supply. Did your new rockers have an oil feed or not? What is it supposed to have? I think 03s have pressurized oil feeds to the rocker shafts and no holes, because if you use 03 rockers on something else as an upgrade you have to put the holes in.

Steve

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The '03 rocker shafts have holes for the oil feed. As do the one's I put in. I removed the rocker shaft and there's no excessive wear on the shafts.

Here is a photo of the rocker shaft showing the shaft holes - Rocker Shaft

When I saw that the shaft was messed up, I thought I'd forgotten to install that tiny o-ring on the head before I put the valve cover on, but it was where it was supposed to be...

berger said:

What was the reason for the last rocker change?

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For the heck of it. I had near 150 hours on the bike when I replaced the auto-decomp so I figured while I had the cam out and all, I'd replace the cam bearings, rockers and shafts, cam chain etc...

The bike was running fine leading up to this. I'd shut the bike off to wait for a slower rider, when I hit the start button it labored to turn the bike over. I kicked it and it started, but shortly thereafter the noise started.

Smorgasbord said:

Have you checked the valve springs if they are still good?

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No, not yet. I've just gotten this far.

ElSnorro said:

If needed i have a cheap replacement rocker arm (2002 model).

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I appreciate it. I have the originals that I removed when I installed this one, but I definitely appreciate the offer.