The bike is a 2003 450es. I bought it a few months ago and it was smoking a little and had very high oil consumption. I decided to rebuild it the right way. I split the cases and cleaned and inspected everything. I had the cylinder bored, installed new piston and rings, timing chain, one way bearing, and valve seals. I also relapped the exhaust valve (intake was fine). I put everything back together and it ran perfect. It was very quiet, no strange noises. After riding the bike around for a about 15 min, the engine developed a tapping sound. I assumed that it was from the exhaust valve tightening up after the recent relapping which could cause the cam follower to hit the decompression mechanism thus making the noise. I reset the valve lash and the new noise is still there. Please follow the link and listen to the noises and give me your opinion. Thank you!

http://www.flickr.com/photos/36035475@N06/3328069785/

During the rebuild I found quite a bit of black sludge that was stuck to the cases. When I rubbed it between my fingers I noticed a slight metallic look to it. I think this is partially due to the the fact that the nut that holds the secondary clutches on had actually come off and was bouncing around inside the clutch basket. I also found a little bit of dirt/crud inside the passageways for the crankcase breather.

I flushed the oil cooler and hoses with clean gasoline. For what its worth, the oil in the engine still looks brand new after 2.5 hrs of riding time.

Also, before the rebuild I had a very similar noise everytime I started the engine. It would go away as soon as I blipped the throttle. I attributed this to the loose nut on the secondary clutches that I mentioned. I figured that the nut was bouncing around at idle and once I revved the engine the centrifugal force would hold the nut on the edge of the basket thus eliminating the noise. The noise would only return when the engine had been shutoff. I have also read that this "noise that disappears once you blip the throttle" could be the decompressor on the cam.

As for the audio, it is much easier to notice the difference in the sounds when you are using headphones.

 

Did you find the noise ?

I will PM you tomorrow a few issues to check .
Late right now and I was just passing through the site

----- Gimpster -----

 

Thanks Gimpster. The noise hasn't been found yet. I haven't had a chance to mess with it for a few days and I am hesitant to start tearing it apart again. One question, the engine has about 2.5 - 4 hrs on it since the rebuild. If I were to pull the cylinder off, would I have to replace the rings or re-hone the cylinder? I don't want this thinkg to start smoking.

 

First check the rocker arms, rocker shaft and holder assembly for wear. Any groove in the rocker shaft, even though the valves are adjusted correctly will still clatter when released from valve tention. If this is the case, replace both rockers, the shaft and the holder.
-Other causes may include the cam chain tentioner and guides worn. This does require cylinder removal you know...
-A one-way bearing in the centrifugal clutch can make this noise if it is chattering. Seen good one-way (sprag) bearings ruined when the centrifugal clutch nut is installed with an impact to push the clutch on without spinning the drum to release the one way during install.
- The small bearing in the front cover that slips over the crankshaft end can be bad or binding. Once again when techs pull the centrifugal clutch off with an impact on the puller, It will slightly deform the end of the crankshaft or mushroom it. When the front engine cover is reinstalled with the crankshaft end boogered up, it causes side pressure on the bearing which quickly ruins it as it is a weak bearing.

Do some listening in all mentioned areas with a stethescope to determine where to start and remember that sounds will echo through the front cover that are not really there. Be thorough with steth inspection.

PM me if you need any more help.... I will clean out my PMs for more space again as I have used up all my provided message limit there again

----- Gimpster -----

 

I spent some time last night trying to diagnose the noise. I am confident that the problem lies in the decompressor that is built on to the cam. I remember that when I first put the engine together and rotated it by hand, I could hear the decomressor working. There was an audible woosh sound right after the intake valve closed. I could also see the exhaust valve opening slightly at this exact moment. I then started the engine and everything sounded perfect. I checked this again last night and the decomressor is not working anymore....It is trying to but it does not actually open the exhaust valve enough to release any compression. It also makes a tap when the lifter is coming off of the decompressor. This is all with the valve lash set at exactly .006" on an 85 deg F engine. I believe that the decompressor is caught somewhere between the "activated" state and "deactivated" state which is causing it rattle around and make the noise.

Other than that, I checked the cam chain tensioner and it is functioning correctly.

 

mine sounds the same after honing and new rings. but started smoking after 3 hrs. how do you fix the decompressor? or will it make it smoke?
took it to a shop and they said it was a loose valve seat..??