New Engine Noise...looking for thoughts

2008 YZ450F

Had kind of a head on collision last weekend on a trail...nothing serious and nobody got hurt because the speeds were pretty low. In trying to get out of the way I got t-boned by the guy and his front tire hit my header and skidplate. He was only going about 10 mph and I was almost completely stopped. It knocked me over but not hard.

After making sure we were each okay I fired up my bike and started riding down the trail but now there was a pretty noticeable sound coming from my motor...hard to isolate & describe but I would say it sounds like something is not getting lubricated like it should. Its not a knocking or clanking. Oil level is good, pulled the oil pressure check screw on the cylinder and oil pumps out very well. Coolant is good. Even changed out the header in case it was some weird exhaust leak but that didn't change anything. Bike fires up and runs great...rode it about 5 miles back to camp after the noise started.

The sound is hard to isolate but if I had to say where the sound is coming from I would say from the head but I'm really not 100% sure. Top end and timing chain has 28 hours on it and the noise started immediately after I got knocked down.

Any ideas or thoughts?

Take the skid plate off and listen again. All it has to have done is to be bent or shifted just enough to touch some part of the frame between mounting points and it can make noises you wouldn't believe. I took one off that wasn't making noise, replaced the rings in the engine, and bolted the same plate back on in the same place. I had the motor part way back apart before it occurred to me it was the skid plate making the noise I heard.

Funny you mention that and actually feel somewhat retarded for not thinking of that myself since he made contact with the skidplate. I drained the oil, checked the filter to see if there was an unusual amount of shavings, then refilled. Fired up the bike and the noise was gone (had not remounted the skidplate yet)!

Start with the simple things, right?

Thanks Gray!

Funny you mention that and actually feel somewhat retarded ...

Well, yeah... :devil:

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