Some may recall that my son's YZ 125 motorcycle self destructed a few months back.
Piston:
Cylinder:
Head:
We sent the head & cylinder to an engineering shop to be repaired & for the Nikasil coating to be redone.
Repaired Head:
Repaired Cylinder:
Finally had some spare time this week, so we removed the engine from the frame, split the cases (which involves removing magneto, clutch & transmission first, so a complete disassembly) in anticipation for the rebuild. The big-end bearing is still fine, so strictly speaking we didn't need to split the cases, but with the damage done to the old piston & cylinder I was sure there would be bits of metal in the crankcase, and I wasn't confident flushing it with petrol a few times would get it all out, so went the rather safe than sorry route - remembering that there is no oil filter on this bike. I'm please that we did, as we cleaned out a lot of debris from the cases!
All parts were cleaned & inspected
The cases & innards once disassembled:
We replaced all bearings - including the main bearings and also replaced all the seals.
Crank installed into one side of the case (Crank was placed in freezer for 2 hours, bearing & case heated up with a heat gun. Crank then "dropped" into position.)
Then began the slow process of reassembly.
Transmission & gear selector dog mechanism (one side of the casing):
Gear selector mechanism (opposite side of the casing)
Clutch basket & pressure plate:
Power Valve & Cylinder with piston installed:
That was it for yesterday - started at 08h30 and finished at just after 15h00. I'm pleased to say that there was very little foul language required and no injuries were sustained by father, son or cats! (Wife & daughter were clever enough to vacate the house for the day!
)
Tomorrow (today now) we will put the head back on & then install the engine into the frame. We'll repack the swingarm bearings at the same time as we reassemble. All going well we should be running by lunch time!
Piston:
Cylinder:
Head:
We sent the head & cylinder to an engineering shop to be repaired & for the Nikasil coating to be redone.
Repaired Head:
Repaired Cylinder:
Finally had some spare time this week, so we removed the engine from the frame, split the cases (which involves removing magneto, clutch & transmission first, so a complete disassembly) in anticipation for the rebuild. The big-end bearing is still fine, so strictly speaking we didn't need to split the cases, but with the damage done to the old piston & cylinder I was sure there would be bits of metal in the crankcase, and I wasn't confident flushing it with petrol a few times would get it all out, so went the rather safe than sorry route - remembering that there is no oil filter on this bike. I'm please that we did, as we cleaned out a lot of debris from the cases!
All parts were cleaned & inspected
The cases & innards once disassembled:
We replaced all bearings - including the main bearings and also replaced all the seals.
Crank installed into one side of the case (Crank was placed in freezer for 2 hours, bearing & case heated up with a heat gun. Crank then "dropped" into position.)
Then began the slow process of reassembly.
Transmission & gear selector dog mechanism (one side of the casing):
Gear selector mechanism (opposite side of the casing)
Clutch basket & pressure plate:
Power Valve & Cylinder with piston installed:
That was it for yesterday - started at 08h30 and finished at just after 15h00. I'm pleased to say that there was very little foul language required and no injuries were sustained by father, son or cats! (Wife & daughter were clever enough to vacate the house for the day!
)Tomorrow (today now) we will put the head back on & then install the engine into the frame. We'll repack the swingarm bearings at the same time as we reassemble. All going well we should be running by lunch time!
