Lost oil drain plug on highway. Now what?

[Dk]

My People S 250 shut off on the highway after losing the oil drain bolt.  No lights warned of engine overheating or oil pressure lacking at any time.  After pulling over, I saw coolant overflowing and then a puddle of oil under the engine.  That is the moment I looked and realised I forgot to torque the oil drain bolt completely - it was gone.  So we towed the scooter home, I replaced the bolt, refilled the oil and checked the radiator/coolant level which was all good, and tried starting it.  It turns but no longer starts.  Considering that the cause was probably the oil leaving the engine, but the engine still turns, what is likely preventing it from starting now?  I will post the solution for future reference once I find out.  I also wonder why I got no overheating light or oil light; they work when turning the key but never did during the riding.

[Stig / Major Tom]

You mention "highway"......interstate?  How long and how fast were you running?
Stig

[hypophthalmus]

The temperature gauge was normal?

The lack of oil light might make sense if the oil hadn't depleted to dangerous level yet. But that doesn't really make sense if it was overheating.

The first thing I'd do is a compression test. You can inspect the spark plug (could be damaged from heat) and check for a spark while you're at it.

[Dk]

Thanks for the suggestion.  I was going about 50 for 15 minutes, then 65 for about 5 until it cut off.  I put 2000+ miles on it in interstate and city driving with no trouble until I lost the drainage bolt.  I still find it odd that no oil or heat lights came on when there should have been  oil starvation / overheating to cause the current problem.  I'll post what I find.

[Louder North]

Thanks for the suggestion.  I was going about 50 for 15 minutes, then 65 for about 5 until it cut off.  I put 2000+ miles on it in interstate and city driving with no trouble until I lost the drainage bolt.  I still find it odd that no oil or heat lights came on when there should have been  oil starvation / overheating to cause the current problem.  I'll post what I find.

If it shut off by itself while on the highway, that was the warning that something was wrong whether you noticed a warning light come on or not. Once the bolt fell out, it would have drained quite rapidly and you may not have noticed the warning light. Regardless, the other suggestions for checking for compression and spark are spot on.

[Dk]

Ok so I finally tested the compression.  It's 25 psi.  I called a dealer and he said that means the engine definitely needs to be rebuilt.

Since I'll be disassembling it myself now (why not at this point) I am considering replacing the engine myself if I can find one, as an alternative to just buying a new bike. Is this engine used in other models, so that if I can find one it would be a fittable swap?

[hypophthalmus]

Complete engines are going to be basically impossible to find.

It's likely that there's a significant amount of interchangeability with different 250 parts, but I haven't confirmed this, and a complete engine swap from different models is out of the question due to differing transmission dimensions.

You'll need to figure out the cause of low compression. It could be that that the cylinder is scored or rings are damaged. Or it could be that the head gasket is blown.

There's a good chance that repair won't be prohibitively expensive.

[john grinsel]

My take you seized the engine---I doubt if you were checking oil level before each ride.....and ran out of oil.   Cost and used value of bike, sometimes makes junking it cheaper and starting over.

[stuo]

Every surface that was lubricated is ruined: rings, cylinder bore, rod bearing, crank bearing, maybe the piston. Your engine is done, cooked. 

[JJJoseph]

Some Kymcos are based on Chinese GY6-type engines and there's tons of cheap replacement and performance parts available.  But others are not.  There's the rub.  I know what GY6 parts can be swapped on my Kymco Sento, but have no information on other models. You just have to cross your fingers and hope that someone appears here who has this knowledge. Without extensive research it's not possible to tell which engine you have.

[Dk]

The engine is on the table now.  How do you turn the A.C. generator flywheel?  The instructions tell you to turn it to set the timing, but it apparently doesn't move by hand.  Is there something else I need to do other than just grab it and "turn" it after I've removed the cylinder head cover?

Regarding parts cost:  I found a complete engine rebuild kit for under 500$ that includes cam shaft and bearings, cylinder, piston, gaskets, and o-rings.  I'll still take a look at the engine first.

TL;DNR version of original post:  the engine turns but makes a compression of only 25PSI.  The cause was the loose oil drainage bolt falling out during riding.

Thanks for the helpful info so far. 

[hypophthalmus]

You turn the engine using a wrench after removing the small round cover on the right side of the engine.

If it were me, I wouldn't worry about rebuilding the engine just yet. Instead I'd see how the head gasket looks, and check the head and block for flatness. Also check for cracks.

[Stig / Major Tom]

Wouldn't there be complete used engines available for much less than $500, if it comes to that?
Stig

[hypophthalmus]

I wish there were. I still have a sad People 250 sitting with a dead engine.

[Dk]

Ok, I found the piston and cylinder scored.  I replaced those.  The bearing rod had virtually no play and turning the engine produced no noise so it seems that a top end rebuild should do the trick.

As I attempt to start it again, on the main kickstand (rear wheel in air) I have an electrical issue.  When the battery is connected, the "met-in" latch light goes on as normal.  The gauges move when I turn the key- normal also.  But when I press the button, I only hear a click coming from the battery area, somewhere just to the right, and the whole dashboard dies/lights go out.  Only when I disconnect then reconnect the battery, it lights up again.

I have no taillights, muffler, rear brake pads, or air filter installed yet, if that matters.  Is there some breaker being tripped?