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I picked up a 2005 Honda crf150f for my son about a month ago. It's been running good, starts right on first or second kick, no smoke and good power...but yesterday it started developing an intermittent rattle noise in what sounds like the top end. With in minutes or so of start up it starts a rattle noise...then maybe goes away for a few seconds and comes back. This noise is different than the usual noise (ticks) it makes...and it stuck right away and is somewhat loud. You can definitely hear it when it starts. My son actually came to me and said what this noise?

The oil has been changed and air filter cleaned, running new gas in it as well (91).

I'm just wondering if the sound is something to be worried about. We've been running it every couple days for the last month and are just now hearing this rattle sound. I don't want to cause more damage by ignoring it...but I'm afraid to take it to a shop to be told I need a complete top end rebuild or something if of course that's not the case.

Could the valve clearance need adjusted? I heard this is a self adjusting cam chain?...so it wouldn't be coming from a loose cam chain?

I posted a video on YouTube to see if anyone can help and possibly tell me what is. The rattle is constant in this short video.

Here's the link:

http://youtu.be/8za8yYxr27I

Thanks in advance for your help. I'm glad I found this crfonly site...lots of good information!


-Brian

Can't say that I hear anything out of the ordinary.

i am having a similar ticking noise and along with that after i rev it up it back fires.
have you figured anything out about it.

The cam chain was rattling...I changed the cam chain tensioner and the noise drastically reduced. I put an automatic tensioner in (factory) seeing how the original lasted since 2005 and didn't care to worry about proper adjustments. I adjusted the valves as well and it seemed to run a little better (wasn't off that much) but that didn't take away the rattling noise described above.

im going to adjust the valves first. hopefully that works if not i will check the chain. thanks