Shaved aluminum in engine??!!

Pirooz Javan · Joined: 16 Apr 2010 Posts: 45

Ran pretty well at VIR about a month ago until I heard a pretty loud sound coming from the engine side. I thought My chain had flown off and hit something, but I noticed everything on outside looked normal.

My engine no longer started so I thought maybe it was a blown reed pedal. Took off carb and saw shaved chunks of aluminum. I opened up the head and also saw it on top of piston....I'm guessing this is a definite rebuild, but was wondering what could cause this.

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2007 Birel M31
Stock Leopard

Chris Hurst · Posted: Tue Aug 21, 2012 12:05 am Post subject:

! How much time was on the motor when this happened? How were you running the motor in terms of carb settings and oil / fuel mixture?

I had my motor stick on me and found some small metal flakes in the bottom end of the motor, but nothing like the size of what you photographed. Mine seized after 13-14 hours from being run way too lean.

The piston looks like it's been seeing a lot of detonation. Can you give some more information about the ignition timing, oil / fuel ratio, carb settings etc. I'm not an expert by any means, still learning, but the more information you provide the more people on the forum can help you figure out what you were doing wrong (if it was you).

Greg Wright · Posted: Tue Aug 21, 2012 7:19 am Post subject:

Looks like a caged bearing failure, either top or bottom. Gonna get expensive I'm afraid.
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Jim Russell, Jr. · Advertiser Joined: 03 Oct 2001 Posts: 1535

I agree with Greg.
Rod bearing failure. Most likely bottom bearing.
Caused by too much time or poor lubrication.
Carb settings do not matter.

Jim jr.
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Pirooz Javan · Joined: 16 Apr 2010 Posts: 45

Thanks all for the replies. The explanations all make sense. Time to send this off for some service!
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2007 Birel M31
Stock Leopard

Jim McMahon · Posted: Wed Aug 22, 2012 8:17 am Post subject:

Only thing I would say is that in my experience running a too lean on the low jet can cause the bottom end to break up.
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