Top End due to oil usage.

[nickjtc]

you can see the damage to the piston and head on #3 cylinder due to lack of a spark plug electrode.

Yup. The little blighter must have danced a jig in there for quite a few revolutions before getting spat out!!

[BruKen]

<no popcorn smilie> Following with interest.

Question : You are low on pressure on two of the three cylinders. No3 can be explained, certainly w.r.t damage caused by electrode, but that doesn't explain the second cylinder's low pressure. Certainly damaged was caused in No3 but that being the cause of the low compression is debatable at this point and doesn't fully explain the oil loss imo as the rings haven't broken. Can you show pics of the barrels interior. It would be interesting to see if your "dieseling" moment wasn't actually a mild sieze and you'be rubbed the honings off. Certainly one piston looks like it has sieze damage rather than particulate damage.

[Sin_Tiger]

Bbbbbrrrrrrr, ting ting ting, Bbbbbrrr. I think you found what happened  Hope the valves survived, piston looks useable, how do the liners look?

[BruKen]

, piston looks useable,

I'd measure it up. It has some lateral wear patterns that look decidedly iffy to me. I really suspect a mild seize being the root cause of the OP's original concern.

[JoeDirt]

I'd measure it up. It has some lateral wear patterns that look decidedly iffy to me. I really suspect a mild seize being the root cause of the OP's original concern.

I'm with BruKen on this one. I would make sure all of your wear surfaces were all in service limits.

[BruKen]

Sin, the OP has posted high res pics that the board has downsized. Click on the piston pic. Notice the wear pattern is much more than a mild scuffing. Oil retaining hone / hatch marks are absent and the ali looks as if it has mild friction rubbing deformities where the ali has been pulled, rather than particulate scratchings. (more obvious on the edges of the wear near the gudgeon pin) If this is mirrored on the barrels then I'd stake money on a mild sieze. Next question is to determine why it seized.

When I did YAPI also in the 40k mile mark the hatchings were still very prominent

[Sin_Tiger]

Fair point, hence my asking about the barrels. I did say 'usable' rather than good, depends what you want to spend. Good point about two cyl rather than just one.

[BruKen]

<ribbing mode - on>

I think that Scots heritage is coming into play  Betcha you begrudge changing tyres come MOT when there's 2mm of tread left and you think to yourself - if I had only come in a month earlier I could scraped through with an advisory and ridden those down to the windings before next year's MOT  :icon_wink: 

Measurements will show. I hope I eat humble pie for OP's sake though. Damn Tiggers can get expensive

[Sparky]

<no popcorn smilie> Following with interest.

Question : You are low on pressure on two of the three cylinders. No3 can be explained, certainly w.r.t damage caused by electrode, but that doesn't explain the second cylinder's low pressure. Certainly damaged was caused in No3 but that being the cause of the low compression is debatable at this point and doesn't fully explain the oil loss imo as the rings haven't broken. Can you show pics of the barrels interior. It would be interesting to see if your "dieseling" moment wasn't actually a mild sieze and you'be rubbed the honings off. Certainly one piston looks like it has sieze damage rather than particulate damage.

It might be a light seizure this area of expertise is above my pay grade that's why everything is going to the machine shop.  I'll get some more pics up later tonight.

I have more experience with two stroke seizures which are a lot more spectacular and leave not doubt as to what happened.

[BruKen]

now if the steamer were a 2 stroke......   

[Sin_Tiger]

They're no worn, they're ma racing tyres pal  got back from Phucket one trip and the rear looked more like a carpet than a tyre 

That piston doesn't look quite so good from that angle 

[BruKen]

Those be 2 stroke pistons Sin. No oil ring see. He's pulled the wool over your eyes you daft bugga.

[Sparky]

Yup they are out of a 787cc Rotax engine in a Seadoo PWC.  Typical two stroke zipping along thinking wow this thing is running great today then it went from max rpm to stall in about 5 sec and I knew exactly what happened.  Turned out the rear carb was a little light on the main jet and therefore my wallet was a little lighter after top end #2   

[Bixxer Bob]

The lack of Hylomar is odd 

The valve seat land should be 0.5 - 0.75mm when you come to check them.....

Any sign of leakage on the head gasket???

[Sparky]

The lack of Hylomar is odd 

The valve seat land should be 0.5 - 0.75mm when you come to check them.....

Any sign of leakage on the head gasket???

Lack of Hylomar is not good lack of any sealant at all is worse.  No signs of head gasket leaks the coolant level never went down.