I have an 80cc 2 stroke engine that's been running perfectly until today. Its a new engine. It won't start no matter what. I've moved the chock back and forth and checked my fuel connection. The only way that gets it to run is to remove the spark plug and cover the end of it with petrol. Then the engine starts and I have to rev it for a bit to get it to stay running. From there it runs perfectly until I switch it off again and the problem repeats itself. PLEASE HELP
Engine only runs when I put petrol on the spark plug
- Thread starter David22
- Start date
aquielisunari
Active Member
What color is your spark plug?
Spark Plug Gap? I'd purchase a new one with a .6mm gap over at Bikeberry but I'm in the US. I'd also make sure that copper(?) ring that's hugging the top of the spark plug isn't loose or too tight. Speaking of the US we also call it a 66cc engine because the way we figure out engine displacement differs from the Chinese. https://motorbicycling.com/threads/why-are-the-engines-called-66cc-80cc-need-info.15910/
I would replace the CDI and the magneto even if it is still relatively new.
Did you change the gas/oil ratio recently? Current ratio? 32-40:1 sweet spot after break in and 16:1 before.
Clean interior of gas tank. That gas tank is usually painted very poorly meaning the paint can flake of and clog or partially the petcock.
Replace fuel lines and filter.
Clean carb thoroughly including the needle, jet, bowl and float.
Because it isn't crazy expensive I would first look to make sure the fuel system is proper.
Spark Plug Gap? I'd purchase a new one with a .6mm gap over at Bikeberry but I'm in the US. I'd also make sure that copper(?) ring that's hugging the top of the spark plug isn't loose or too tight. Speaking of the US we also call it a 66cc engine because the way we figure out engine displacement differs from the Chinese. https://motorbicycling.com/threads/why-are-the-engines-called-66cc-80cc-need-info.15910/
I would replace the CDI and the magneto even if it is still relatively new.
Did you change the gas/oil ratio recently? Current ratio? 32-40:1 sweet spot after break in and 16:1 before.
Clean interior of gas tank. That gas tank is usually painted very poorly meaning the paint can flake of and clog or partially the petcock.
Replace fuel lines and filter.
Clean carb thoroughly including the needle, jet, bowl and float.
Because it isn't crazy expensive I would first look to make sure the fuel system is proper.
Hi thanks for your response. I'm thinking that it's more likely an issue with fuel because when the engine eventually ran it stayed running meaning that the spark plug was firing. I drained my carburetor which seemed to be flooded with fuel and cleaned it out then when I put it back on the engine and let the fuel flow into it. It still wouldn't start. I'm running the engine on 16:1 unleaded: 2 stroke motorbike/moped part synthetic oil. And I checked to see if my spark plug was sparking by taking it out and spinning the rear wheel. (it does) when I put fuel on the spark plug now all it does it fail to start but jolt randomly because it fires briefly. I have attached a picture of my spark plug to this message. Thanks again!
aquielisunari
Active Member
When you take the bowl off the carb look at the bottom of the carb. You will see two curved metal tines that you can pull down MAYBE an eight of an inch. I mean you can pull them down further but we aren't looking to bottom out the float. Those tines regulate how full the bowl gets similar to the way a toilet bowl's fill mechanism works. It doesn't thin or richen the fuel but it can help those overflow and leaking issues.
aquielisunari
Active Member
I see threads on the end of that spark plug which means it's missing its cap or at least that's been my experience. I'd be Googling cars, trucks and rec. vehicles that aren't starting right either and need starting fluid.
Sidewinder Jerry
Well-Known Member
This often times can be a simple fix. You could be getting a vapor lock. Take your gas cap off and see if the bike cranks. If it does simply put the cap back on. If your cap has a vent valve check it to see if it's sticking. Some have a small hole in them that can get clogged.
Hi thanks for all your responses. I have tried starting it with the fuel cap off and it worked once but wouldn't work again. Also I had petrol at the end of my spark plug during this which would have helped. I didn't think the cap at the top of the sparkplug was necessary, in fact the instructions that came with my motor said to remove it. The engine has previously ran perfectly without the spark plug cap. Also here is my carburetor bowl.
