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Post by leeroypenmut on Aug 30, 2023 14:53:53 GMT -5
My son has a 2019 Lexmoto echo 50cc and is having a few problems -
Wont start using the electric starter - kick starter works after 1-2 cranks (quarter throttle)
New Battery installed
Will not idle when cold - bogs down after half throttle - under powered - overheats/gets very hot
I have removed the carb and cleaned it - fuel is running ok - spark is ok (not the best but ok)
I have set the carb up lots of times, one day the mixture screw needs to be fully in to run and not bog down, another day it needs to be backed out a couple of turns to get power to go up slight hills.
The bike has a couple of mods - roller (lighter and heavier) - aftermarket exhaust (no lamba sensor (still plugged in but not in exhaust)) - cone filter.
These mods were done a few weeks before he started having trouble.
if anyone can help that would be great - we are spending more time fixing it than he is riding it
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Post by geoffh on Aug 30, 2023 15:01:36 GMT -5
Welcome to the forum,just general pointers,get rid of the pod filter and back to stock,change the plug,check that the exhaust has no leaks,let us know from there.
Geoff
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Post by aeroxbud on Aug 31, 2023 3:00:45 GMT -5
I think the problem is your exhaust. The system is designed to lean out the mixture through letting air in. This is controlled by the lambda sensor, and solinoids. I think it works a bit like the Piaggio Euro 4 system.
It's not getting the correct signal.
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Post by GrumpyUnk on Aug 31, 2023 7:49:19 GMT -5
With the sensor exposed to ambient air, it may be sending garbage signals to whatever controls the carburetor.
If you still have the electronically controlled carburetor, it likely will not work properly without signal input. Most O2 sensors diddle with the mixture by going rich/lean in response to the content of the exhaust gas. Uncontrolled or lacking signal, it may wander around looking for a signal and response, depending on its control program or mechanism.
If you are running a non-stock carburetor, that's a zebra of a different color.
tom
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Post by leeroypenmut on Sept 6, 2023 12:31:16 GMT -5
Welcome to the forum,just general pointers,get rid of the pod filter and back to stock,change the plug,check that the exhaust has no leaks,let us know from there. Geoff Hi Geoff He doesn't want to remove the cone filter, the exhaust is all good, we have put a new spark plug in but no difference. |
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Post by leeroypenmut on Sept 6, 2023 12:45:06 GMT -5
I think the problem is your exhaust. The system is designed to lean out the mixture through letting air in. This is controlled by the lambda sensor, and solinoids. I think it works a bit like the Piaggio Euro 4 system. It's not getting the correct signal. The moped was running fine with the exhaust for a few months. As far as I can see there are 4 sensors/controllers - lambda sensor, two vacuum valves & position sensor. The 2 vacuum pipes have been blocked with ball bearings & the lambda sensor is tied up out the way. How can the ecu control the carb? how can it adjust the mixture? |
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Post by leeroypenmut on Sept 6, 2023 12:57:55 GMT -5
With the sensor exposed to ambient air, it may be sending garbage signals to whatever controls the carburetor. If you still have the electronically controlled carburetor, it likely will not work properly without signal input. Most O2 sensors diddle with the mixture by going rich/lean in response to the content of the exhaust gas. Uncontrolled or lacking signal, it may wander around looking for a signal and response, depending on its control program or mechanism. If you are running a non-stock carburetor, that's a zebra of a different color. tom Hi Tom I was thinking its the ecu messing with the mixture but can't understand how! I would imagine the lambda sensor checks the exhaust for richness and the ecu opens/closes the vacuum pipes to control mixture but with the lambda sensor removed from the exhaust & the vacuum pipes blocked how does the ecu control the carb? |
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Post by GrumpyUnk on Sept 7, 2023 10:40:46 GMT -5
Most systems are designed to 'fail safe' such that a failure of the Lambda, for example, will force the computer to go rich to prevent damage due to going too lean. Just like a failed thermostat in a water cooled vehicle engine will(should) fail in the wide-open position. That prevents overheat and possible damage.
I do not know if this is true, but I expect the engineers would do this to avoid customer complaints that a failed sensor ate their engine/piston.
Using an 'adjustable' carburetor with the control mechanism locked out is defeating the purpose of the controls, in both directions. It will not respond to changes in temperature or exhaust gas content.
I would consider the carburetor is operating in 'default mode', so the engine will run, not burn up, and pop a signal to the operator that something is wrong. I dunno if codes are available,but expect the thing to post that the O2 sensor is dysfunctional. Most systems fail 'rich' as the sensor will not produce voltage when it is not buried in hot exhaust gas. Low==Lean for non-wideband, so the system will add fuel(or lift a needle?) when it fails to produce voltage. Wideband? Ask the man who owns one.
tom
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