I have a 2000 300ex and in just the past month or so it has developed an engine noise. I don't hear it all the time only during a certain rpm range from just past 1/2 throttle to just before full throttle. When I let off the throttle I can hear it again when the rpms are dropping. It happens under load and no load. I thought it might be my valves so I adjusted them for the 1st time since I got it two years ago. They were a little loose but after I adjusted them it made no difference on the noise. The bike runs fine but its just that this noise doesn't sound too hot. It doesn't matter if it's cold or hot it still does it the same. I have always changed the oil according to schedule and am currently running 10w40 Mobil synthetic. The noise sounds kinda like it's coming from the head area. I hate to say it but it kinda sounds like somethings rattling. I really hope it isn't my cam chain cause I really don't want to tear it apart. The only mods I have done are a K&N jet kit, filter, and FMF exhaust. If I get a chance I will try to record it and post the wav/mp3 file. Anybody else ever heard of this problem? I thought these engines were supposed to be bulletproof like it says in the honda brochure. oh well thanks for any help

 

it could possibly be that the timing chain is too loose and is hitting up against the side of the case. Is the noise coming from the right side of the head? if so, it is probably your timing chain needing tightened.

 

MY 300EX started ticking about a month after i had a WB Full Race Cam installed. It was the cam working loose and the rockers were contacting it. MY engine was blown in a week. I would have it checked out. DEFINTATELY!

 

I don't think it can be the cam chain since its self adjusting. Its not very old so It shouldn't be stretched anyway. I would definetly take off the cam cover and see whats going on.

 

I will go and try to record this wonderful noise when I get back from work. I really really hope it's not the chain. I will post a link when I can

 

I had a noise like that in my 250X. I rode it like that all summer, and then one day in the fall one of my cam bearings disintegrated. Nothing left but the two races.

 

I have a 300ex and the motor has been incredibly reliable and most are. It sounds like the cam chain but could be something else, I would look toward the top of the motor for something loose. If it was deep in the motor it would probably be a lower pitch sound, if it's real rattly its probably on top.
I wouldn't sweat it if it is the cam chain, as a matter of fact that would probably be one of the easier fixes that it might be. If you need info on changing it send me an e-mail and I'd be happy to help out.

 

Well, I really feel stupid now. [img]i/expressions/face-icon-small-blush.gif[/img] [img]i/expressions/face-icon-small-blush.gif[/img] [img]i/expressions/face-icon-small-blush.gif[/img] Guess I should take back that stuff about Honda's not being bulletproof. I was gonna take off my FMF and put my stock exhaust back on to see if that made a difference with the noise. Well, I started to take the bolts off the header and the lower one was just a little loose. I took it off and cleaned and filed down the end of the pipe to try and make the surface where it meets the head a little smoother/flatter. I put the FMF pipe back on and start it up. Believe it or not it seems like the noise is almost gone now. I will have a much better idea when I go riding this weekend, but for now it seems like its mostly gone. Listen to the wave file. The first few seconds I was holding the microphone (a crappy little pc one) near the front of the engine near the exhaust outlet. The next few seconds are towards the back of the engine. Let me know what you think...


Engine noise