I just finished making all the engine mods for my 400ex (see signature), and now it has a loud ticking. My question is, are there different valve clearance settings for the xr400 cam? They were adjusted after the new cam was put in, but I still am getting a very loud valve tick from the top of the motor. What should I do?

 

Did you replace your rocker arms when you put in the new cam? If not the ticking you're hearing is most likely the cam and rocker arm surfaces contacting unevenly (since one is old and one is new. I'd replace the rocker arms to be on the safe side. If they shatter you'll need a whole new cam and rocker arms.

 

I bet you found the right exhaust valve really tight and corrected it.

If that's the case, you rotated the engine backwards and activated the compression release.

Tear the valve covers back off and readjust the valves - it's likely that only the right front needs correction.

.004" for the intakes
.005" for the exhausts

 

No, I didn't get new rockers, I know I should have, but I had a VERY fixed budget. Will they eventually wear in (like piston rings do to a cylinder wall), or will they have to be replaced?

 

250rampage,

What octane were you told to run with your 11:1 piston? I am having an 11:1, stock-bore Wiseco piston installed, and I would like to know if I have to run 110 octane. Do I? Thanks.

 

well i might just say its the rocker arms

mine did the exact same thing. I figured according to FSTs advice that i didn't need hardwelds right away.

Well he was wrong. And my rockers took out my cam and arms.

So i'd just get the hard welds and reset everything before damage occurs

 

Running the HRC is no different than running the stock cam. Hardened rockers are not required or necessary. New rockers are not necessary. It is HIGHLY unlikely that you need new rockers. And no, the rockers aren't worn unevenly - even if they were, they wouldn't cause tapping. Tapping is caused by one thing - the rocker leaving the surface of the camshaft because it is adjusted too loose.

The HRC cam is equipped with a decompression assembly. All this jumping to conclusions is quite unfounded. You would have noticed a problem with the rockers if there had been one when you reassembled the engine. Even if this cam required "hardened rockers" damage wouldn't happen instantaneously, it is a gradual thing. Readjust your valves per my last post - this time don't rotate the engine backwards - not even a little, if you go past TDC, go all the way back around (read the service manual, it will tell you the same thing).

Take it from someone who's been there and done that, twice -- right front valve...

 

No straight 110 octane would be way overkill. Pump premium will likely be fine - I run 2 parts pump gas to 1 part race gas, but only for the added safety margin for racing - really, pump gas would be fine in my engine.

 

Counter-Clockwise is the correct way right? I wasn't sure so I checked to see which way the starter rotated it, and it was ccw. Could this be my problem? We tried reajdusting them today but it made no difference. I also thought that it would be odd for the rockers to all at once go to a loud ticking, not a gradual increase. I will try it again, and make sure not to go backward, even a little, and see if thats my problem.

 

I have been going crazy with the same problem. My mods are almost the same. Port and polish, modified head pipe, e series pipe, 416 bore, 11-1 piston, web cam 450-451 grind, rev limiter, etc. I rode it a little and it runs good but then I also noticed the loud ticking sound. I ask around and was told to adjust the valves. First I adjusted to the stock specs. Still same problem. Then to the new cam specs, still same problem. I am no mechanic and this is getting old and frustrating.