# 80cc motorised bicycle motor stalling all the time



## Christine Fletcher-Jones (Dec 20, 2018)

i purchased a 80cc 2 stroke motor of ebay ran fine until chain snapped now it will start but surges and stalls at idle when you twist throttle it just surges and dies there bubbles in the fuel line but the breather cap is not blocked has a new cdi unit and new spark plug runs for about 2 minutes.


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## geogrubb (Jul 28, 2006)

Sounds like a fuel line problem check that they are not cracked or pulled out of the tank too far to pick up fuel. Have a good one. Geo


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## Christine Fletcher-Jones (Dec 20, 2018)

*80cc*

its a solid screw in on/off reserve fuel cock and new fuel line it does get bubbles


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## Christine Fletcher-Jones (Dec 20, 2018)

this is the fuel tap


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## finaprint (Jan 29, 2006)

If the carb has a float then air bubbles in line mean nothing, the fuel de-aerates in the bowl.

If the problem truly started when the chain snapped I would be looking at any possible damage from that like around the sprocket area, maybe the chain end whipping around or bunching up cracked crankcase or other. 

If the mag rotor is on that side maybe it sheared a drive key or something.

Think in terms of 'sudden stop' damage.


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## Christine Fletcher-Jones (Dec 20, 2018)

checked all cogs and bearings all secure and no damage just annoys me its been ridden for 5 minutes literally didn't even get out of the driveway until there cheap chain snapped


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## finaprint (Jan 29, 2006)

Maybe it had the problem all along but not run long enough to discover it yet.

You could pop the fuel bowl to see if a brand new jet was not tightened to fall out or similar. Idle mixture not set right could do it.

Why a new CDI on what essentially was a brand new one anyway? The airgap has to be carefully set if it uses one. Plug gap is not preset either and needs checking.

If chain was set too tight it WOULD pop pretty quick.


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## sboricic (Oct 10, 2009)

https://motorbicycling.com/threads/so-your-ht-bicycle-engine-wont-start-well-lets-take-a-look.35090/

I'd check the cylinder head bolts and all other bolts to be sure they are tight. Replace the engine mounting bolts or they will snap over time. Do not use the rubber provided with the kit to mount to the frame. Go medal to medal. Lots of other info on the link I provided above.


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## paulr44 (Oct 14, 2008)

Ran fine until chain snapped?
I'd say either chain hit a fuel line, agreeing with other responses,
or on far-left scale flywheel key bent/sheared.


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## Hobby Dude (Aug 7, 2019)

2018, im sure its fixed by now, or replaced...


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