'94 CR250 with new L.A. Sleeve, piston and clacking noise.


5 replies to this topic
  • N6VMO

Posted June 16, 2006 - 07:56 AM

#1

In April 2006, we had L.A. Sleeve install a stock bore sleeve in my son's 1994 CR250. We are using a new Weisco two ring piston (replicates stock OEM)

Since then we have been experiencing a 'clacking' noise at idle to just above idle. This is not a pinging noise.

Compression is as good if not better than the day we got it back from L.A. Sleeve.

You can listen to the 'clacking' here:


Last night we pulled head to check things out. Here is what we found:
http://www.xylicon.com/misc/piston.wmv
The video shows the piston being rocked back and forth. This seems like excessive movement to my layman eyes. The video also shows the top of the piston and mixture indications, no white or excessive carbon.

Phoned L.A. Sleeve to ask them their opinion. One service tech said "it appears to be normal. Weisco forged pistons are tapered from the top down. They also make more noise being a forged piston." (larger at the bottom and smaller diameter at the top)

Another service tech quoted the same taper opinion and will look at the video/audio files and call me back. No word from him yet.

Please view and listen to the files and provide us with your opinions.

Thanks

  • Dan CRF250

Posted June 16, 2006 - 08:06 AM

#2

thats how they all sound, the connecting rod makes that noise when the crank shaft hits top dead center

  • Dan CRF250

Posted June 16, 2006 - 08:17 AM

#3

revise:
the knock is the noise of the skirt of the piston getting thrown to the opposing side on the cylinder wall when the connecting rod goes over top dead center.

My cr250 makes the same noise, yours is a little more excessive then his, but you also have a sleave in it, which could change the tone of the noise.

the little movement of the piston you will find in all bikes, in the manual there are tolerences of piston skirt wear and cylinder size. if you really want to get into it try measuring your skirt for wear or your cylinder, i wouldnt worry about it too much, my cr did it since the day i bought it and it still runs as good if not better then when i purchased it

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  • LocoP

Posted June 16, 2006 - 10:53 AM

#4

Bring the engine up to operating temp and it should get a little quieter. The piston rock on the top of the piston is normal since the rings under pressure will center the piston. The bike does sound normal for being cold. :excuseme:

  • SilverSurfer

Posted June 16, 2006 - 02:22 PM

#5

Because the Wiseco piston is aluminum it tends to expand more than steel. I believe the Wiseco pistons are built purposely a little smaller than the stock bore so when at operating temperature it will not sieze up.

FYI, my Wiseco piston sounds like that too.

  • VintageDave393

Posted June 16, 2006 - 08:01 PM

#6

That looks like excessive clearance even for a Wiseco. I would have the cylinder measured and also measure the piston. The clearance should be .003 in. I am guessing that you have more than .006 based on your video.

BTW, your top ring looks really carboned up from oil. When was the last time you replaced the tranny side crank seal?





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