Originally Posted by jackd
That would be 'Jimbee' up here in Vancouver. He had quite the mess on his hands. The saddest part was that he went to the trouble of re-buiding the engine, with much encouragement from the forum members. Eventually he was having problems with the cylinder hold down studs pulling out of the block which led to further repairs. I was wondering if somehow the block had lost its strength where the studs thread in. I'm hoping that it came to a satisfactory resolution at the end.
Appropriate thread timing - this is about the 2 year anniversary of the "incident", and I'm still sorting out the damage from the bike being left to idle on its centre stand until it died (estimate 45 min). Want to emphasis the encouragement and help I have received!
As a point of reference for this thread, couple details about heat and damage:
Think the saving grace in my case was the plastic bearings on the rocker arm - as the oil burned off and stopped flowing to the rocker arms, the plastic bearings started to chip away until the end play on the rocker arms was so much that valves weren't being acuated fully, thus killing the engine.
During that time the bike got so hot that the plastic crankcase breather valve thingy below the starter melted into a pile of plastic and both the oil and neutral swtiches began leaking.
In terms of damage to the engine after being heated to plastic melting temperature:
- there was some wear on the cylinders but it didn't apear that the actually engine seized
- the big end bearings looked good (thus I have assumed main crank bearing is good too)
- two lifters showed some pitting (could possibly be from before - never looked at them before)
- had to replace all of the rocker arm bearings - many broken cages due to severe end play
- several of the cylinder studs pulled out upon reassembly, but not sure how much the combination of past weakness from possible overtightening from PO plus any lateral expansion of the cylinder and head due to heat played a role vs. actual weakening of the cylinder block as a result of heat
- after all of this, despite new rings and perfect compression measurments (132 and 127 psi), still I ended up with serious oil consumption (~1L/800km). Not knowing where the oil was going (other than out the exaust), I have since honed the cylinders, sent heads to Tom Cutter, and reinstalled w new rings. Now waiting to sort out a charging issue before breaking in the new top end and reporting back.
All it all, I suppose it could have been worse.