Looking for help to diagnose.

Video:  

It's an 01 that I picked up a few months ago.  Ridden twice and seems to run fine despite this noise.  I'm afraid it will cause (more) damage if I continue to ride.  Looking for help as to what needs to be rebuilt.

Go to an auto parts store and get a mechanics stethoscope or put a long screw driver to your ear and touch different areas until you find the location. The location will become more obvious the closer you get to the noise

Edited by AXAxiom, 05 May 2012 - 09:06 AM.

Does it have same or worse rattle when revving?

Mine sounds pritty much exactly the same but mines a bit more quiet, and most CR's ive come across sound the same. I replaced my topend and crank seals/bearings and the noise is still there.

There was side too side play on my rod, but no up and down. So now I have peace of mind, but if I was you I would just ride it untill you plan on doing a topend and inspect everything while you're there.

Edited by noysy1, 06 May 2012 - 03:13 AM.

shrubitup, on 05 May 2012 - 09:14 AM, said:

Yes this. Its sounds pretty normal.

Is the PV linkage working correctly? The CR chatters PV alot but that one sounds very loose.

It sounds fairly loud but normal for a cr. if you really want to try to fix it start with the basics. Change the tranny oil, new plug, make sure every bolt you can reach is torqued to spec, etc. good luck and happy trails, that thing looks sick!

sounds just like my 250, its piston slap, my 250 has a wiseco piston in it and they are noisy. The reason i dont think its the pv is because our cr80 makes the same noise but much quieter and it has no pv. I just live with it, its made the noise since the day i put the wiseco in there.

I tried the screwdriver to the ear again and it seems to originating, or loudest, near the PV on the right side.  I wonder how much of that could be misleading because of the water jacket of the cylinder.  You can actually hear the distinct tapping by just placing the sdriver to the frame near engine..  

Regardless, I ordered a new top end and hope to put it in this weekend.  It has an ART piston right now.  I have an A cylinder and will be putting a C piston in.  Previous owner only had it about a year and did not do a top end.  Said guy he bought it from did one before PO bought it.  Cold compression check was about 120 psi on a good gauge.

I'll keep you posted.  Thanks all for the input.

check if you exhaust big one is bent and touching and metal parts , most likey the radiator, or left side of the engine, sounds like metal is touching and vibarating... sounds pretty normal. dont worry about it

This exact issue gets posted almost every 2-3 weeks.  I wish the mod would put a sticky up there explaining what causes it and how to fix it.

So, take your cylinder and piston off and remove the ring from the piston.  Stick the piston in the cylinder and shake the top of the piston at various places in the bore.  It gets noticeably looser in the exhaust port area.  The noise is the piston rocking in the bore because the bore is so out of round and they come that way from Honda.  You can get your cylinder replated to straighten out the bore or simply get a ProX incremental oversize piston to tighten up the clearance.  They have four sizes and I've had good luck the the third oversize in all four of my CR125's.  Good luck...

When I first noticed the noise, I checked for parts contacting and vibrating.  Couldn't find anything ... even re-routed cables per the service manual.

Float, I'm hoping the larger piston will do the trick.  I have a C piston (53.96mm) being shipped now.  I'll try your ring-less piston check when I do the top end.

I've had other riders suggest the bottom end bearings, reeds, fuel mixture, oil level ... you name it.  Was hoping to get a definitive diagnosis online here.  I'll post my troubleshooting to hopefully help the next fellow out.

Did you measure the bore?

robfromga, on 17 May 2012 - 04:52 AM, said:

I tried but I didn't trust it.  I measured like 53.7mm with my Harbor Freight digital caliper.  I'm guessing it should be high 53.9 though since the piston is already that.