I'm stumped on this one. I have a '99 400ex. When the engine is warmed up, i'm getting a pretty loud ticking noise. I checked the valve clearance. Intake=.004, exhaust=.005. Right on according to my dealer. I have stock jetting, stock exhaust, k & n filter on it and a splitfire plug. A friend told me to replace my exhaust seals between the engine and the header, posible leak. I can't feel any leaks. It does seem like the noise is the loudest beside the header on the right side of the engine. Possible valve seat? I'm not losing any oil. Is it the plug maybe? Jetting? My dealer told me that 4 strokes make engine noise, nature of the beast, but i'm just not totally convinced. Anyone else have this problem before I spend some money on having it checked out by the dealer?

 

It is unusual for a Honda to experience valve noise. If it is running lean, the head temperatures could be higher than normal, causing valve clatter. Have you rejetted since the K&N? If it isn't lean, I'd leave it alone until you experience other problems. Most Kawasakis and Yamahas and suzukis experience valve train noise once they get up to operating temps in the summer, so you probably don't have anything to worry about.

 

I have the same thing happening to my 250X. It just started recently. Valve clearance is perfect.
i haven't noticed any loss of power, or any other problems so i just figured i'd wait and see what happens.

 

on a older machine like the 250x mentioned it could be the timming chain streaching and causing noise but not likely on a new one

 

Oil breakdown? My 400ex had 10w40 in it and did that. I switched to 20w50 and it cleared right up.

 

That makes sense. I use 10w40. I just changed it too! Do you use the synthetic?

 

I'm assuming (ya' know what happens when you assume, though) that the Honda brand is synthetic. My 400 is only a week old today, though. So it could have been that I was running it a little too hard during the break-in period. Hmmm, made sense to me, though..

 

Timing sprocket bolts have come loose. need to take valve cover off and timing chain sprocket. Clean sprocket with gasoline and put back together using loctite on the bolts. Allow to dry at least two hours before starting.

 

is this a pretty easy fix? I don't have a manual. I'll tear into it tonite and see if i can do it. thanks for the help.

 

Had the same problem on my XR400, turned out to be the auto DE-comp cam having to much clearnece and tapping the rocker arm when the engine got real hot, I just adjusted it and the sound went away