Help, ran straight oil. Won't start.

Levimoody

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Sep 24, 2019
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Ok, I know I'm going to get some **** for this but I ran straight oil now she won't start, it'll pop and fire every 3 rotations of the pedals. I took the head off, cleaned it out with gas and cleaned the carb. No plugged jet. I'm at a loss of what to try next, I've dumped the old gas and properly mixed some new gas. I changed the spark plug, the CDI and magneto, it's getting a spark, the air filter is fine. It acts like there is water in the gas. Please give me some feedback. Here's a picture of it. Haven't got around to cleaning it up but after I get it running I'll clean it up.
 

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Greg58

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May 1, 2011
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Welcome to the forum, You probably have oil in the crankcase, you could have loaded up the muffler too. Wait I don't see a muffler. When you say you cleaned the carb did you remove the needle and main jet? Could have oil build up in either.
 
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Levimoody

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Sep 24, 2019
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Yeah I had the muffler off for that photo, how would I go about draining the oil out of the crankcase and how would that interfere with it starting? Also is it fine to run a 2-stroke without a muffler, my brother had said that that needs back pressure or it can seize it up?
 

Greg58

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May 1, 2011
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Yes you can run without a muffler but it will only be louder, not faster. A piston port 2-stroke requires back pressure to run best, that's why a good expansion chamber helps so much.
 

Levimoody

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Sep 24, 2019
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Yes, blew air through the main jet it's clear. I'm gonna take the crankcase tomorrow and wash it out. Can anyone tell me why this would effect the engine. I'm really kinda new to the scene.
 

Levimoody

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Sep 24, 2019
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Also how do I adjust the timing? Maybe when I was replacing the magneto coil I had messed that up?
 

Killall4u

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Nov 14, 2019
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It seems like I am in the same boat as you. Perfectly clean and adjusted carb, good spark, and good compression, but won't start. I even replaced the plug, cdi, and magneto, still can't get to start. I'm wondering if getting liquids in the crankcase could effect anything. Anyone know about this?
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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If you filled the engine with oil, it won't start because oil doesn't burn (not like gas, anyway.) So if you've got spark, the oil is putting it out.

Think of it like dipping a birthday candle in a puddle of oil. It goes out, and won't relight because it's soaked. That's what's happening to your plug.

The only way it'll start is to get the oil out. Changing parts won't do anything. You need to flush it out.

Best way to do it is take the motor off, remove the head, carb, and exhaust, and then pull the jug off, spray a ton of carb cleaner in the case and tip it over and dump it out. Repeat as many times as it takes, till oil isn't pouring out.

The messy way to do it is leave it on the bike, pull off the carb, pipe, and plug, spray carb cleaner in and pedal til it blows all the oil out everywhere.
 
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Killall4u

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Nov 14, 2019
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Best way to do it is take the motor off, remove the head, carb, and exhaust, and then pull the jug off, spray a ton of carb cleaner in the case and tip it over and dump it out.
By jug do you mean the cylinder? Also i have cleaned the inside of the cylinder out where the top of the piston is, but would oil down in the crankcase below the piston cause it to not start? You mean dump out the oil from below the piston right?
 

bairdco

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Aug 18, 2009
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By jug do you mean the cylinder? Also i have cleaned the inside of the cylinder out where the top of the piston is, but would oil down in the crankcase below the piston cause it to not start? You mean dump out the oil from below the piston right?
Yeah, jug is the cylinder. The way a two stroke works, is the fuel mixture enters thru the intake under the piston and gets pumped back up thru the transfer ports and ignites above the piston, forcing it down, etc.

So the oil went straight to the bottom of the case and puddled there, because it can't get pumped back out.

If it's full of oil, it has to be dumped out and flushed.

But, depending on how much oil you dumped into it, you might be able to run straight gas (no oil) in the tank after cleaning your carb, jets, fuel line, etc.
If you try this, take off your exhaust pipe, leave the plug in (so it has compression) and pedal your ass off and it might blow all the oil out.

Then you'll have to clean or replace the plug.

Oil doesn't flow well thru carb jets, so it might not have filled the case. But still would be enough to stop the gas from igniting.

It might get to the point where it wants to start when you're pedaling. If it does, stop immediately, because you flushed out all the oil and you're running straight gas, which will seize the piston.

Mix up a new batch of oil and fuel, and hopefully it runs.
 

Killall4u

New Member
Nov 14, 2019
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Yeah, jug is the cylinder. The way a two stroke works, is the fuel mixture enters thru the intake under the piston and gets pumped back up thru the transfer ports and ignites above the piston, forcing it down, etc.

So the oil went straight to the bottom of the case and puddled there, because it can't get pumped back out.

If it's full of oil, it has to be dumped out and flushed.

But, depending on how much oil you dumped into it, you might be able to run straight gas (no oil) in the tank after cleaning your carb, jets, fuel line, etc.
If you try this, take off your exhaust pipe, leave the plug in (so it has compression) and pedal your ass off and it might blow all the oil out.

Then you'll have to clean or replace the plug.

Oil doesn't flow well thru carb jets, so it might not have filled the case. But still would be enough to stop the gas from igniting.

It might get to the point where it wants to start when you're pedaling. If it does, stop immediately, because you flushed out all the oil and you're running straight gas, which will seize the piston.

Mix up a new batch of oil and fuel, and hopefully it runs.
Thank you for all the help. I put a syringe down in there and pulled out a half oz of oil, then I blew into it with compressed air for a few minutes. She's running good now.
 
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