Hi, I recently purchased a 1999 WR400F, and today, a clicking noise started coming from the engine. It sounds like it's coming from under the valve cover. However, I just changed the oil and filter, and had to loosen up the header to do so. When I started the bike and took it out for a spin to warm it up, it started making the clicking noise after 2-3 minutes or riding, and gets louder when the rpms increase. Other than that, the bike seems to be running just fine. Would the header be the primary suspect, or am I missing something?
Posted June 18, 2014 - 09:33 PM
Clicking would not likely be header. If it was misaligned it would most likely suck air and you would get a backfire on decel.
Take the valve cover off.
Pull decomp lever and get someone to kick it over so you can have a good look and listen without it starting up.
Posted June 19, 2014 - 05:10 AM
If the clicking is rythmic, it is in the valve train, and is most likely a broken shim bucket.