Engine shut down and Chain popped off

GoldenMotor.com

JohninHawthorne

New Member
Apr 14, 2014
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Hawthorne, CA
total newbie, I got a used motorized bike as a gift with no instructions other than it uses "regular gas and how to start it". I've been reading up on it and come to find out that I need a gas oil mix. So after using it a while with regular gas it locked up and the chain popped off and it wouldn't start after I was able to get the chain back on. Any suggestions? I'm guessing I need to correct the gas oil mix problem first, and grease up the clutch, am I right?
 

Greg58

Well-Known Member
May 1, 2011
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Sorry to be the one to tell you but it sounds like it has seized, without the proper oil mix the piston will kinda melt to the cylinder. Remove the spark plug and see if the engine will turn over, if not add a little oil in the plug hole and maybe it will free up enough to get the cylinder off to see how bad the damage is.
 

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Ditto:
It might already be too late to save the engine but parts are available to rebuild it.
2 cycle, or 2 stroke engines do not have a oil sump or pan and rely on the oil mixed with the fuel to lubricate the internal workings. Without oil you essentially have metal to metal contact in all of the moving parts inside your engine. No oil, no lubrication. The result is usually what Greg said. Damaged pistons and cylinder walls as well as bearings.

The chain coming off was probably the result of the engine seizing. That is the least of your problems right now.

Good luck and let us know how you do.
And welcome to the forum. Sorry you had to join with that kind of problem to solve.

Tom
 

JohninHawthorne

New Member
Apr 14, 2014
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Hawthorne, CA
Thanks Greg, thanks 2door, so pretty much in the worst situation I'd have to buy a new motor, best case I might have to buy a few new parts. The first thing I should try is remove (unscrew) the sparkplug and try and start it like I normally would. If it doesn't start I should put some Oil (what kind of oil) in the sparkplug hole can I use any kind of oil or only two stroke engine oil?

If that doesn't work should I take it to a shop like Beach City Cycles In Manhattan Beach, CA or take it apart myself and try and figure out which parts are damaged and replace them myself.

I'll take some pix today get back to you two with an update. Thanks Again.
 
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2door

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Sep 15, 2008
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Littleton, Colorado
If you'd like to learn about your engine and experiment a little do the disassembly yourself. There are lots of good tutorials here that will explain engine tear down and reassembly for you.
I'd try a little 2 stroke oil down the plug hole first. That might loosen things up if the damage isn't too bad. Maybe a couple of spoonfuls then try to pedal the bike, clutch engaged and the spark plug out to see if the engine is seized. If you can't pedal it, you have some serious damage that will require possibly a new cylinder and piston rings.
Good luck. Let us know what happens.

Tom
 

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
In retrospect I'd just try turning the engine over with a socket on the magneto side before trying to pedal it. With the plug out and the clutch disengaged it should rotate easily. Don't force it with that nut. If it doesn't turn then you'll know that the piston is probably seized in the cylinder.

Sorry I mislead you in that previous post.

Tom
 

xseler

Well-Known Member
Apr 14, 2013
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For us with enquiring minds, how long did the engine run before it 'stopped'? Would kinda like to have an idea of how 'forgiving' these engines are.....
 

Kioshk

Active Member
Oct 21, 2012
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Connecticut
So...my FIRST engine seizure occurred during a long, abusive trip. Fortunately it happened near home. I think it happened due to a combination of my naivete and poor oil-mixing technique. You see, it was November...it was cold...and I had the BAD habit of trying to mix the oil IN-TANK. This would result in globs of pure 2-stroke oil fouling the carb initially, and then riding with too little oil in the fuel afterwards...I was a dope. In this case, although the engine siezed, only one ring of the pair was damaged, and the jug-melt was minor. I was able to lightly dremel and buff both the piston and jug-wall and put the bike back in service while I awaited my new rings.

Personally, my first step in this situation would be to remove the jug and assess the damage...I wouldn't try turning it over at all; there is the potential you could make worse what could be a simpler fix. Since you hadn't been using oil, I'm leaning more towards taking the entire engine off the bike and splitting the case to inspect the roller-bearings (as well as the two needle-bearings). The combustion-chamber's roller-bearings are relatively inexpensive, and easy to replace...they're also probably mildly, if not efficiency-killingly damaged. You now also have the specter of potentially damaging debris in the crankcase as well...like a sneaky time-bomb...a tiny chunk of metal could be lurking in there only to loose itself at cruising RPMs and lodge itself comfortably between the cylinder, piston, and ring: KABOOM!

As there was no mention of the proper oil-mix, I suggest that going forward you PREMIX 87 Octane with run-of-the-mill ash-free 2-stroke oil at about 25:1 . I premix my oil 4:1 with hobby-store gumless castor-oil...the type they use in RC planes and cars. It's super cheap, and provides excellent lube and forgiving protection. It also smells nice.

Now, DON'T screw up your _PRE_MIX AGAIN!

Curious: who sold you the engine, how old was it, did the seller ride it, and how many hours was on it?
 

JohninHawthorne

New Member
Apr 14, 2014
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Hawthorne, CA
I only rid it for about 4 to 5 hours and not all at once longest rides where 20 minutes long., I have no info on how old it was, but I do know that the old owner did ride it
 

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
I only rid it for about 4 to 5 hours and not all at once longest rides where 20 minutes long., I have no info on how old it was, but I do know that the old owner did ride it
Well, the guy who sold it to you was negligent for not instilling in you the dogma that these engines need oil mixed into the fuel. 2-strokes and oil: it's like the complete opposite but just as ubiquitously known as eyeballs and solar-eclipses!
 

JohninHawthorne

New Member
Apr 14, 2014
7
0
0
Hawthorne, CA
If you'd like to learn about your engine and experiment a little do the disassembly yourself. There are lots of good tutorials here that will explain engine tear down and reassembly for you.
I'd try a little 2 stroke oil down the plug hole first. That might loosen things up if the damage isn't too bad. Maybe a couple of spoonfuls then try to pedal the bike, clutch engaged and the spark plug out to see if the engine is seized. If you can't pedal it, you have some serious damage that will require possibly a new cylinder and piston rings.
Good luck. Let us know what happens.

Tom
this site is kind of hard to navigate where is the tab to find those vids you mentioned?
 

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
Also make sure you take advantage of the search feature located at the top of each page. It's not that obvious, but is an excellent and invaluable resource.