New 2-stroke engine won't start

2stroketalent

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I'm having trouble starting my brand new 80cc 2 stroke bicycle engine. When I pedal up to speed and release the clutch I can hear the engine firing, and it fires as long as I keep pedalling, but dies as soon as I pull the clutch back in. I've tried again and again but the engine dies each time.

I'm following all the correct starting procedures as far as I can tell (20:1 gas/oil mixture, pump a bit of gas into carburetor, choke closed). The spark plug is definitely working, and I've double checked the wiring.

The problem might be low compression. I don't have a compression gauge, but I did the thumb-over-spark-plug hole compression test, and didn't feel much pressure. Even with the spark plug screwed in tight, I can push the bike forward and turn the motor over with a bit of effort.

Any suggestions on how to solve the issue?
I've bought 3 new engines on Amazon recently, (SAME PROBLEM, No start!) and all 3 were incorrectly timed from the manufacturer. Sent them back for a refund. The woodruff key groove on the crankshaft was cut in the wrong position. I removed the key and set the mag approximately a whole key width or more off the cut groove. Tightened the mag in this position. (can't remember which direction, but go left first) Voila!! Started and ran. Needed a bit more adjustment to run right, but at least it ran. Returned anyway. I'm not sure if the maker knows this, but Amazon doesn't seem to care, as they sell so much that they can afford to and not loose customers or insignificant profits. Working on a fix (rebroach or adjustable mag mechanism)
 

Karl Snarl

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I've bought 3 new engines on Amazon recently, (SAME PROBLEM, No start!) and all 3 were incorrectly timed from the manufacturer. Sent them back for a refund. The woodruff key groove on the crankshaft was cut in the wrong position. I removed the key and set the mag approximately a whole key width or more off the cut groove. Tightened the mag in this position. (can't remember which direction, but go left first) Voila!! Started and ran. Needed a bit more adjustment to run right, but at least it ran. Returned anyway. I'm not sure if the maker knows this, but Amazon doesn't seem to care, as they sell so much that they can afford to and not loose customers or insignificant profits. Working on a fix (rebroach or adjustable mag mechanism)
I've bought from CDH for only God knows how long ( like a long damn time), never had that problem. Never really had any problems with CDH. Few shipping damage claims, but it's not their fault and they took care of me quickly and fairly. No name engines are hit and miss. Seems some companies buy the scrap junk and sell it.
 

brian2331

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I don't think it's a problem with the clutch. I tried adjusting it like you suggest and the clutch got looser and looser until it wasn't biting, so I put it back to where it was.

I'm able to push the bike forward with the clutch fully engaged, and the motor turns over, so I'm pretty sure it's a compression issue. I listened closely I and I could hear air being pushed out when the piston goes up.

On closer inspection the head does look a bit rough, so I'm going to sand it flat on a pane of glass. I've attached a picture of the inner surface of the head. There's a thin ring of metal sticking up from the surface that has a few scratches and gouges. Is it safe to sand the ring down flush with the rest of the head?
Hey how you doing I recently bought an 80CC bikeberry motor bike.

Now I bought it on impulse and didn't pretty much got ripped off.

I completely forgot that a good friend of mine does these things for a living and has his own bike channel on YouTube called Johnny's motorized bicycles.

I brought it to Johnny, he tore the engine apart and put it in a sonic micro cleaner. He said that my piston and rings looked good but The cylinder walls had 2 light scratches.

He put the motor back together and I went to pick the bike up and drove it home about 10 miles. It ran perfect and I got it up to 39 mph But I was told by him To never ride these motors with the throttle fully open so I was told You should only Driving about 25 30 mph. Even old motors are capable of going faster.

But anyways, after 4 days having riding it 6 miles in a 20 minute ride, at WOT, I went as high as 36 mph, but my average speed was19 mph.

I wasn't riding it at full throttle when I arrived at my destination and the motor just completely shut down, It didn't make any noises like stalling or bogging out, it just shut off like I hit the kill switch.

So now I got back on it, pedal it, release the clutch, and nothing happens.

So whats happening now is if I release the clutch lever to where the clutch is supposed to engage, the back wheels still spins freely instead of locking up...What does this mean???


Moderators Note:
I went ahead and tried to not only put in punctuation, but also gave sentences and paragraphs some proper spacing as well as correct wording, sentence structure, syntax, etc. in order to make this readable for everyone in order to help out...It was totally unreadable the way it was.
 

FrizzleFried

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Hey, how you doing? I recently bought 80CC bike berry motor bike. Now I bought it(?) No I bought it on impulse and didn't(?) Pretty much got ripped off. I completely forgot that a good friend of mine does these things for living, has his own bike channel on YouTube called Johnny's motorized bicycles, and I brought it to Johnny. He tore engine apart put it in a sonic micro cleaner. Said that my piston and rings looked good but the cylinder walls had a 2 light scratches. He put the motor back together. Got on it, start a ride up, now I went and picked the bike up, I drove it home about 10 miles. It ran perfect. Speed was 39 mph, but I was told by him to never ride these motors with the throttle fully open. So I was told you should only driving about 25-30 mph. Even old motors are capable of going faster. But anyway after 4 days have having it, I drove 6 miles, 20 minute ride on my speedometer Max. I got up to 36mph, average speed was19mph. So I wasn't riding it at full throttle. Right as I got to my destination, the motor just completely shut off. It didn't make like a stalling like bogging out noise, or puttering, it just shut off like I hit the kill switch. So now I got back on it and pedal it, release the clutch and nothing happens. So I'm replying to you because I know this about the clutch. When I called my buddy that rebuilt the engine He told me to pull in the clutch, and walk with the bike release see what the back wheel does. The back wheel, when I released the clutch, still spins instead of locking up. What does this mean?

Cleaned it up a bit ...

That means the clutch isn't disengaging. That means you need to adjust the clutch so that it disengages. You can do this down where the clutch cable meets the engine clutch "lever"... and you can make fine adjustments at the clutch "hand lever"...
 

DAMIEN1307

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Cleaned it up a bit ...

That means the clutch isn't disengaging. That means you need to adjust the clutch so that it disengages. You can do this down where the clutch cable meets the engine clutch "lever"... and you can make fine adjustments at the clutch "hand lever"...
Re-read it as I have made the many corrections that were needed to even translate what he wrote...The rear wheel still is in freespin even when he lets the clutch lever out to where it is supposed to engage...At least thats the best I could make out trying to translate the 'Sanskrit' it was written in...lol.
 
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