Bottom end failure - 2018 EC300

[Booki]

So I have the motor apart and found a damaged ignition side bearing.

The other side bearing looks pretty toasty - the black i believe is burnt oil, there is also a bit of pitting on the case as well!

Anybody have any insights on how I can prevent this?

[Booki]

Originally Posted by blitz11

I think that you must be a much better rider than am I.

I had 440 hours on my piston (bottom end hours unknown - but tight with just a bit of polish on the small end of the rod), but i rarely ride it on the pipe, and most of that time was riding behind my daughters (both of whom are now faster than I am). My piston has much less ring-blow by, the bottom of the piston was shiny clean, and I had no scoring or "abrasions."

My guess is that you might have had a less than ideally sealed air filter, bad air filter (i had an air filter split on the outer layer once - ouch), or really lean oil mixtures. It's hard to say without more information. i could send pictures of the piston if you're interested.

Dirt might explain a bottom end failure, too. Hard to say for sure w/o the tear down.

Definitely not a better rider! I normally stick to the low end power of the bike and am hardly on the pipe giving it a hard time.

I didn't really see any dirt/debris in the case or on the piston, the intact tract was pretty clean too - so not sure if its related to dirt.

I noticed I had the pilot jet one sizer smaller than stock, the piston measured a bit undersize otherwise I can't really see anything else out of the ordinary, hopefully more knowledgeable people will chime in

[Gasser Nate]

It looks very dry in there mate? Bit rusty and dusty too?

[Booki]

Now that you mention it, it was quite dry...Something is wrong with those bearings getting the correct lubrication I think?

I have not torn down a 2 stroke motor before but would have expected at least some oil down there?

Bike was running a 40 pilot instead of a 42, not sure if that would have made a huge difference..

[blitz11]

Good eye on the dry. When i pulled my top end, looking down past the rod, i had a puddle of Klotz R50 in the bottom end. (I also have spooge issues, but i'll take a bit of spooge to have some "splash" lubrication down there. )

Hmmm. Blocked bearing lube passages from the transfer port area?

[swazi_matt]

any chance it has been drowned and left with water in there?

[Gasser Nate]

Or accidentally been run without oil?

[swazi_matt]

Originally Posted by Gasser Nate

Or accidentally been run without oil?

yep, suppose running it with no oil for a while would burn off any residual oil in there till it is bone dry, fail and then any moisture in the air would start rusting the crank

[Booki]

Originally Posted by blitz11

Good eye on the dry. When i pulled my top end, looking down past the rod, i had a puddle of Klotz R50 in the bottom end. (I also have spooge issues, but i'll take a bit of spooge to have some "splash" lubrication down there. )

Hmmm. Blocked bearing lube passages from the transfer port area?

Originally Posted by Gasser Nate

Or accidentally been run without oil?

Interesting - My bike also had spooge out the exhaust as well, that dry oily stuff that looks like a nest? I wonder if it was run without oil, I always premix my fuel but I did leave my Jerry can at a mates place and maybe they tampered with the fuel...I assume its unlikely but still a possibility. Though I would have thought a top end would have siezed and not spun a bottom.

The oil passages to the bottom end were not blocked at all.

[Booki]

Originally Posted by swazi_matt

any chance it has been drowned and left with water in there?

Has been drowned during my time, around 70 hours ago.

Tipped up side down, spark plug out and water pumped out - started it up and rode the rest of the day. Drained gearbox oil and didn't think anything else of it.

Unless it had been drowed before my ownership within the 5 hours of use from the previous owner, but seems unlikely.