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How about coasting downhill, with compression/engine braking, but not periodically pulling in the clutch or reving to let gas/oil into the cylinder to lubricate and cool it? The cylinder was starved of oil and overheated.
Pelayo
Oakland, CA
From: John M. Stafford <scooteristi@...>
To: 2StrokeSmoke@yahoogroups.com
Sent: Wednesday, July 8, 2009 9:21:16 AM
Subject: Re: TSS: Smallframe piston seizure diagnosis?
Air leak: Loose exhaust. Loose cylinder head. Loose spark plug. Blown flyside seal. Loose carb. Dry packing on the intake manifold (the felt ring on a smallframe between the inlet manifold and carb must be greased at all times).
No lubrication: You failed to premix oil into your gas at a 50:1 ratio.
Over lubrication: You put too much oil in the mix and this displaced gas and thus too much air was in the mix causing it to run hot and seize.
Improper break-in: 100 miles on the motor and you decided to gun the motor before it was ready.
Crap metallurgy: You just happened to have poorly forged ring that came apart on its own and seized your motor in the process.
Enjoy,
John M. Stafford
On Jun 28, 2009, at 2:58 PM, jfribz wrote:
I bought a rebuilt smallframe locally, drove it maybe 100 miles commuting to work. So, one day when driving along, the scoot seizes...on the flat, at moderate speed & rpms. Until this happened, the scoot ran fine, and I've had no problems with it. I think I was premixing correctly, following the instructions of the previous owner. The scoot did have a 133cc kit on it (don't remember the name). Took it apart & this is what I found:
the jug with the head off
underside of the head
the ring, in pieces
grooves in the cylinder wall
Any thoughts on why this might have seized? Any similar experiences or possible diagnoses appreciated, meanwhile I'm going to try to track down the info on which kit was installed.
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