Engine Trouble Bike not starting after removing top end. Metal shavings possibly messed it up

There's an obvious difference in size. Come to think of it, bikeberry may have replaced my 48cc with a 66cc and never told me. It would explain why the M6x1 rethreading kit I bought didn't fit, and then I had to go buy a M8x1.25 kit that did work. Why would a 48cc have M8 studs?
I'm sure they made some 48cc in a 8mm stud configuration. I dont that for 100% sure. But I'm betting they did.
 
I removed my top end recently to rethread the threads in the casing for the head bolts. When i removed the top end I noticed that my bottom O ring was broken, and removed it. I've heard somewhere it will run fine temporarily with one O ring on the top. I got some metal shavings down in the engine, but hoped it would be OK. Sealed it all back up pretty well and got it started.

It's difficult to describe the running. Engine had difficulty starting and it felt very weak. I was able to get it up to 15mph but no more. Anytime I slowed down without throttle it immediately died.

After riding it more gently a few times it got worse. Squeaky sound when peddling with clutch in but I suspect that's from misaligned motor (I loosened motor mounts to make room for my drill when redrilling hole).

Overall very weak power, instantly dying. Hard starting. Feels weirdly smooth. Now it has quit starting.

Did O ring fall down in the engine or did the metal shavings fk it up? I doubt bad compression would make it run this badly.


This is a 48cc engine that bikeberry from 3 years ago that I've had running off and on in the past. Alot of the time it has been running lean and leaking oil all over the motor, but i fixed the compression issue a few weeks ago via the oil ring seal. At this point I wouldn't mind spending $150 on a Seeutek 66cc motor kit because the problems with this thing have been endless.
Terrible lesson :(. I bet the shavings got transfered from the crank case to the cylinder and port walls.. over time I can predict this would cause scrapping depending on how large they're. I wouldn't say the cylinder is trashed Completely but I can reasonably guarantee honing it may give it more life. But seriously not worth it. The transfers have some bad areas that need to be filed. Could be past factory casting but the run wear is toasty. Not sure if it looked this way before. But honestly... Hawk the motor to the part graveyard and get a new kit. Think of it this way with China dolls. You'll spend more money and time buying parts separately then buying an entire new kit possible inherit a lemon or an apple.

Without a doubt however with a very high automotive sand paper you can salvage this for a later project. But it isn't going to run great..


Match up the pistons from the other top end bikeberry kit. If the holes on the piston kit match. You're game. No piston replacement. Possibly just rings and that other cylinder is probably salvageable.


After assembly. If say definitely check the squish gapping. To be sure the piston has clearance to the cylinder head. With the head on, plumber solder bent to an L. I believe if it's between 8mm-10mm? You should have enough clearance for the spark plug. Taking a mm off the cylinder head gasket area with 140 topped off with 600 grit and measuring with a digital caliper can reduce gapping (vice versa). You will have to drill out the stud difference. After all the cost in parts and tools. It's not worth it.


Wanna spend a good 150 and don't care for top performance. Get a Zeda 80-100. Wanna go crazy? Get a Phantom 85 V3. Wanna go nuts. Get a Minarelli. Wanna go absolute lunatic . Get a Athena.
 
Also most people with C.Gs have to do a top end rebuild at some point and 2 stroke dirtbikes' top ends wear out too. One of the downsides of the 2 stroke. Never had a 48cc but I had 2 66cc engines and one my neighbor was using lasted a few thousand miles and I still have the cylinder it is really smooth with no visible scratches.
 

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Also most people with C.Gs have to do a top end rebuild at some point and 2 stroke dirtbikes' top ends wear out too. One of the downsides of the 2 stroke. Never had a 48cc but I had 2 66cc engines and one my neighbor was using lasted a few thousand miles and I still have the cylinder it is really smooth with no visible scratches.
You figure these little engines are putting out 8-13K rpm, that's a lot of cycles per mile.

Unfortunately, one event, be it overheating, lean condition or dirt, you cut their life expectancy way down.

I've had a 2 stroke Nitro R/C engine last 9 gallons, .28cc running up to 36,000RPM you wouldn't see a 4 stroke engine that size survive like that!

Just like Rotary engines are unreliable in a passenger car, but proved to be super reliable in the 787 race car.

Reliability is subject to it's application.

I'm just waiting for the day fan cooled engine kits with better quality become the norm, but we are a very niche market.
 
Terrible lesson :(. I bet the shavings got transfered from the crank case to the cylinder and port walls.. over time I can predict this would cause scrapping depending on how large they're. I wouldn't say the cylinder is trashed Completely but I can reasonably guarantee honing it may give it more life. But seriously not worth it. The transfers have some bad areas that need to be filed. Could be past factory casting but the run wear is toasty. Not sure if it looked this way before. But honestly... Hawk the motor to the part graveyard and get a new kit. Think of it this way with China dolls. You'll spend more money and time buying parts separately then buying an entire new kit possible inherit a lemon or an apple.

Without a doubt however with a very high automotive sand paper you can salvage this for a later project. But it isn't going to run great..


Match up the pistons from the other top end bikeberry kit. If the holes on the piston kit match. You're game. No piston replacement. Possibly just rings and that other cylinder is probably salvageable.


After assembly. If say definitely check the squish gapping. To be sure the piston has clearance to the cylinder head. With the head on, plumber solder bent to an L. I believe if it's between 8mm-10mm? You should have enough clearance for the spark plug. Taking a mm off the cylinder head gasket area with 140 topped off with 600 grit and measuring with a digital caliper can reduce gapping (vice versa). You will have to drill out the stud difference. After all the cost in parts and tools. It's not worth it.


Wanna spend a good 150 and don't care for top performance. Get a Zeda 80-100. Wanna go crazy? Get a Phantom 85 V3. Wanna go nuts. Get a Minarelli. Wanna go absolute lunatic . Get a Athena.
1000001680.jpg

Finally grabbed pictures it's a bit dinged up...
 

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