How siezed is too siezed?

RoadRunner · Sep 22, 2002

I lost the tranny-side crank seal on my bike a few days ago. Upon diassembly it looks like it started sucking air after it ran out of tranny fluid to burn. There are light scratches around the bore of the cylinder, slightly more so toward the top of the cylinder. Actually, I can't tell if they are scratches or if they are aluminum from the piston. It was making an ugly knock just before I shut it off. I can find no play in the crank bearings or the con-rod. Could the tranny fluid and lean condition created the knock or is it the piston? The piston actually looks really good. Would it be okay to run a hone up and down the cylinder to clear out any aluminum and put it all back together or should I get out the big money?

David Trustrum · Sep 23, 2002

How seized is too seized? Hmm. Gurus have pondered this question since the dawn of time. Well the ones who had to buy their own bits have.

The problem is removing the ally & not just smearing it all around.

Caustic soda (drain cleaner).

Apply to a rag with some water to dampen & lay in the affected area. Leave for some while. This attacks the aluminium but not the plating. Should come off onto the rag. Keep it off unplated areas of course.

Clean area with scotchbrite pad & inspect that plating is still intact under bright light.

Warning: Caustic soda is the most lethal stuff you can buy at the super market.
Wear gloves & eye protection.

As for the knock I would keep looking for the source.

Is the ring free in it’s groove or has it been smeared in it’s land?

RoadRunner · Sep 23, 2002

The piston looks amazingly good. The area above the rings has a few scratches, but the rings are totally free. After further observation, I think my cluch-side main bearing is toast, which probably caused the seal to partially fail slowly over time. Then the bearing finally gave up the ghost which completely overwhelmed the already leaking crank seal. There is no up and down play in the bearing, but it has a spot where friction is a little higher and it makes a really faint growl at that point too.

So I guess big money will be involved either way. I'll measure the piston clearance and ring end gap. If they are okay I think I'll run them again. Of course now I need $120 worth of crank bearings :(

How siezed is too siezed?

RoadRunner

David Trustrum

RoadRunner

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