rocker arm disaster

I was starting my 01 400 EXC to warm up for a race and it was making a terrible knocking noise. Luckily, a friend talked some sense into me, and I raced his bike and brought mine home to inspect. One rocker arm roller is oily and rolls fine. The other is dry, burned, stretched, out of round, and missing some of it's needle bearings. It appears that the oil line is designed to shoot oil right down on top of both of them. I am wondering if my pump is weak, or the line plugged, but then shouldn't both rollers be dry? Help somebody. Also, since my cam is ruined, should I consider an after market cam, or go back with stock? Thanks.


I sent you a private message unrelated to this topic.


What year 400 are we talking about, just for reference? I'd guess you're right on the oil line being okay since it was just the bearing. I'd further guess it's just a bad/prematurely burned out one. When was the last time the valves were adjusted?

I don't know of any aftermarket cams available for these bikes so you may not have much choice there.

Hey Jeb,

Nice talking to you again. The bike is a 2001 400 EXC. Forgive my ignorance, but I have never adjusted the valves.

I ride only about once or twice a month, and still think of the bike as new. I guess not any more. I ordered the parts

from Mike's Cycle today, looks like about $300.00. There was a lot of metal (including some needle bearings) scattered

on top of the head, and some down in the ignition cover. Also some fine metal grindings on the screens and magnet.

Do you think it would be a mistake to not tear it down completely? I have washed it out with diesel a couple of times

and would like to stop there, but am not sure if I dare. I was planning to race on the 22nd. My buddy wants me to

install a 470 piston and completely go through it, but I am pretty happy with the power, and don't have a lot of

money. Your opinion would be appreciated.



I hate to sound harsh but I'd guess your problem may have been caused by not adjusting the valves. That could've put undo stress on that roller bearing. See the 2nd link in my sig file for a how-to on that. Teach yourself how to do it. It's really not that hard.

Should you do a tear down? Personal call having to do with comfort level. When I had the cam bearing go in my 01 400E, I was missing 2 balls when all was said and done. I used kero to flush the motor. I crossed my fingers and kept riding figuring between the screens and magnet in the lower end. something would catch them. They both came out at the same time at my next oil change. Came out of the lower screen hole.

Those needles are tiny so I wouldn't think they'd cause a problem but who's to say? Maybe small stuff is worse as it can get picked up easier in the oil flow? The screens should stop that, though.

Good luck with your decision

Thanks Jeb,

I can handle harsh if it helps. You can bet that I'll stay on top of the valves from now on. How often do you check them?


After the first 3 hours and then about 3-4 times a year. Our riding season is kind of short up here in MN.

Here is an update that should be interesting. After some investigation I discovered a plugged banjo bolt at the bottom

of the oil line that goes to the rocker box. The material plugging the hole was some kind of fluff (fiberous, maybe paper,

possibly paper towel or lint). I'm racking my brain trying to think of anytime that such material could have gotten into my

engine. Do the filters ever decompose? They don't appear to be that kind of paper, but I haven't yet cut one up.

Any suggestions? When turning the engine over with the starter, and the spark plug out, the oil pump could not force

oil through the line, although we could blow through it easily. Then we discovered the plugged bolt. The hole in the

bolt is 1 MM., and easily plugged. Apparently the bolt has a restriction in it to force oil to pressure up other places in

the engine. Comments anybody? The oil was about 200 miles old, the filters more like 700 miles.

"fiberous, maybe paper". Could it be gasket material? This is very strange indeed. Have you checked your oil filters and air filter for damage? JEB may have mentioned it I'm not sure but, check your two screen filters to see if there is any thing trapped on them. Keep us posted. This is very interesting. Thanks, Paul

Was the bango bolt plugged completely? Just wondering if it could've been something from the factory and it's just slowly caused the problem. Could've even been something that got in on the last oil change even, I suppose.

I'll be pulling the banjo bolts on both ends of that line soon. Wish I'd read about this earlier. I had the bike torn down, pipes off, etc this weekend for some PM, valve check and WP seal replacement. It would've been the perfect time to check that. Oh well, thanks for the heads up.

valves being out of adjustment should not cause a rocker arm to fail. it was probably just a bad casting or bearing. its a tough call on the total rebuild. personally, i would fully disassemble the motor to guarantee that all of the debris was removed. good luck.

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