Is it worth fixing??

Tyler6357

Well-Known Member
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5:12 AM
Joined
Sep 28, 2011
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Santa Barbara, CA, USA
Hello everyone, I'm still very new here. Here is my situation. I decided to put a motor on my old mountain bike a few months ago. Unfortunately, I got a cheap 66cc/80cc 2 stroke China special. It was the only 2 stroke engine I could find that would ship to CA. I have driven it only 500 miles and today while I was coming home it totally lost power and started backfiring. I adjusted the idle screw to get it to stop backfiring but it just has lost its power, I limped it home at about 11mph. I figured it was a fuel problem so I took apart the carb but everything looked to be working fine. I then thought the problem could be that the muffler might be starving it because I could hear loose parts inside so I took apart the muffler and tightened the screws that had become loose. However when I took the muffler apart I found several small medal balls that look like ball bearings. I think these must have gone through the cylinder and out the exaust and got stuck in the pipe. I haven't taken the head screws off the motor yet. I haven't looked at the cylinder or anything yet. Have I blown something inside the engine? Is it at all worth trying to fix? Keep in mind that I got the entire kit, with the engine, for only $165 shipping included. I'm not a mechanic! Is it pretty easy to replace these ball bearings? Can I purchase these bearings and replace them myself for cheap or is it not worth it?
Thanks to all who respond!
Ride-on
 
First of all are they actually "BALL" bearings, meaning that they are round? Or do they look like broken needle bearings? The only place you will find a ball bearing is from the 2 crankshaft bearings, and if so the engine has to be split to replace them. Here is a picture tutorial of taking the engine down.
http://s982.photobucket.com/albums/ae309/Ron-Becker/Chinese HT breakdown/
 
Thank you for your help. I am definitely going into the engine just to inspect for damage and to see if it is salvageable. If I can replace whatever is broken and if the cylinder is still ok after having pieces of medal run through it I will try to fix it myself I guess. I will purchase replacement parts from your store if I decide to try to fix it.
 
Prolly a head gasket.

Usually when something like that happens I feel like GOD is telling me to tear her down completely have a look and put er back together, it usually works.
 
are you positive that they are ball bearings?
if they are ball bearings from the crankshaft, the engine shoudl have locked up.
besides that they more than likely would have fallen down into the lower part of the engine. For them to make it into the muffler, they would have had to find their way onto the top of the piston (which would have locked the engine up), and then out to the exhaust. since the piston is solid (doesn;t have any holes in it), i see no way for bearings from the crankshaft to make it on top of the piston. if ball bearings were on top of the piston, they would have been between the top of the piston and the combustion chamber and the piston never would have made it's full stroke....it would have just locked up.
what i think you have is welding slag from the cheap welds when they weld the muffler together.
if what you have are ball bearings, i'd be curious as to how they actually made it out of the engine without locking it up.
post a pic, of these bearings so we can see exactly what you have.
This is just my opinion, and I could be totally wrong, but i really don't see how ball bearings from the crankshaft could have made it into the muffler.
 
motorpsycho...I'm with you on this. If it is actually a "ball" bearing, he's got to be one lucky guy, for the engine to not to lock up and destroying anything....oh so many things could of gone wrong. I doubt that it's a bearing to begin with. Strange things can happen.
 
Update

Hi guys!
First: I took some pictures of the small balls and pieces of metal that I found in the exhaust pipe. I took some pictures next to a tape measure so you could see how big they are (see pictures 2251-2253). Anyone know what they are from??

Second: I took the engine off my bike and took the head screws off to check for damage to the piston and the cylinder. I noticed some nicks in the piston from when the medal pieces went through the engine. There are 2 on one side (see pictures 2254-2258) and 1 on the other (see pictures 2261 and 2262). You can see scratches down the side of the piston too (see pictures 2254-2258). Does this piston looked too damaged to use or are those scratches and nicks no big deal? The cylinder itself looks pretty clean with no scratches on the inside (see pic 2259).

The piston seems very loose. I can turn it about 25 degrees or so. I took a picture of it (see picture 2255), then turned it as far as I could and took another pic (see picture 2256). Also, the up and down has a lot of play in it too. Is this normal or is there something wrong? Also, I don't see any piston rings, shouldn't there be rings around the piston or am I wrong?

I haven't taken the rest of the motor apart yet but before I do I was hoping someone could give me an idea of what I might be dealing with and what could have happened. Any recommendations on what I should do next? I'm not really a mechanic and I'm a total rookie taking engines apart.

Thanks
 

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well, your piston rings are there (they are the 2 rings in the slots cut into the piston).
by the looks of that piston, i would have to say that something definitly went past the piston to cause those grooves in the sides. But, you say that the cylinder bore is not scratched?
hmmm, those peices don't look like bearings to me tho. they look more like peices of broken piston ring in a way.
the piston is trashed in my opinion.
i still don't see how peices of anything made it past the piston and out the exhaust tho, unless the rings are broken and that's what those peices are.

was the cylinder really easy to slide off of the piston?
if the rings are right, you should have had some resistance when sliding the cylinder off of the piston, because the rings are what ride on the sides of the cylinder, not the piston.
the piston doesn't actually touch the bore of the cylinder, just the rings do. by the looks of your rings tho, i'd say that there's no way that they could be touching the cylinder bore all the way around. they appear to be sticking out of the grooves only a little bit and only on one side. the rings should be sticking out from the piston all the way around. when you slide the piston back into the cylinder you should have to compress the rings slightly to get them into the cylinder bore.
look closely at the rings and see if there are any missing peices.
If i am correct, there should be pins in the piston ring grooves to keep the rings from rotating, but i've never had one of these apart that far.
I think either you broke the rings, or the ring pins came out, but that's an aweful lot of metal for it to be the ring pins.
I'm guessing broken rings...but you never know, that stuff could actually be from the crank shaft bearings.
since i've never had one this far apart before, i'm just guessing.
I'm really surprised that it ran after this happened because by the looks of the rings, it probably had very little compression.
thinking more about it, i think if it was the crankshaft bearings, it would have eventually locked up.
 
Last edited:
Yes, strange things do happen. Looks like the bearings found their way up between the cylinder wall and the piston and out through the exhaust pipe. Looks like someone is in need of a new engine. As cheap as these things are, I wouldn't try to rebuild it. I'd just throw it away and buy a new one !
 
Update2

well, your piston rings are there (they are the 2 rings in the slots cut into the piston).
by the looks of that piston, i would have to say that something definitly went past the piston to cause those grooves in the sides. But, you say that the cylinder bore is not scratched?
hmmm, those peices don't look like bearings to me tho. they look more like peices of broken piston ring in a way.
the piston is trashed in my opinion.
i still don't see how peices of anything made it past the piston and out the exhaust tho, unless the rings are broken and that's what those peices are.

was the cylinder really easy to slide off of the piston?
if the rings are right, you should have had some resistance when sliding the cylinder off of the piston, because the rings are what ride on the sides of the cylinder, not the piston.
the piston doesn't actually touch the bore of the cylinder, just the rings do. by the looks of your rings tho, i'd say that there's no way that they could be touching the cylinder bore all the way around. they appear to be sticking out of the grooves only a little bit and only on one side. the rings should be sticking out from the piston all the way around. when you slide the piston back into the cylinder you should have to compress the rings slightly to get them into the cylinder bore.
look closely at the rings and see if there are any missing peices.
If i am correct, there should be pins in the piston ring grooves to keep the rings from rotating, but i've never had one of these apart that far.
I think either you broke the rings, or the ring pins came out, but that's an aweful lot of metal for it to be the ring pins.
I'm guessing broken rings...but you never know, that stuff could actually be from the crank shaft bearings.
since i've never had one this far apart before, i'm just guessing.
I'm really surprised that it ran after this happened because by the looks of the rings, it probably had very little compression.
thinking more about it, i think if it was the crankshaft bearings, it would have eventually locked up.

Okay, I can see the rings, I just had to wipe the grease away, haha. The rings each have one break in each of them. I'm not sure if that is by design (so you can get them on?) or if they are broken. I suspect that they are broken. They don't rotate on the piston but I can make them flex out slightly around the breaks. I don't see any pins but it's possible my eyes just can't see them but I don't feel any. Also, the cylinder did have some resistance when I slid it off the piston, not alot, but it didn't just slide off. I took some pictures of the breaks in the rings the top one (see pic 2064) and the bottom one (see pic 2065). However, I agree that there was too much medal in the exhaust pipe to simply be only the pins. The pieces of medal look like round balls. Some of them got crushed going through the piston but one of them looks like it is hardly banged up at all and it is a perfect ball like a small ball bearing (see the one on the right in picture 2253 above). I should say that I had to zoom in with my camera to get the pictures of the nicks and scratches on the piston above, they are actually very small (less than 2 mm wide) and less than (1 mm deep). The largest one (picture 2262) is about 2mm wide and at just over 1mm deep. They might look larger in the pictures than they actually are. Also, the cylinder surprisingly has no scratches for grooves, it only has one very slight nick that is so small I can barely feel with my finger. How this can be I don't know.
 

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