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dt125lc backfires


lizzie40f
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i have a dt125lc that has an intermittent fault which is sometimes it starts and runs fine but other times it starts very lumpy and keeps cutting out then backfires,i have cleaned out the carb but it made no difference

when it is just about running it wont rev up then cuts out and backfires,also i am not sure but i had the cover off the left side of engine and the stator wheel spins when its struggling to run then when it cuts out the wheel spins the opposite way and if you still have kick start down it kicks back up

any ideas guys

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if the engine is running backwards then that would explain the lumpy starting/running, could be caused by extremely advanced ignition timing causing the fuel mixture to pre-detonate and the engine to run backwards, i used to have this trouble when hand-starting model aircraft engines, a common remedy was to open the throttle and drop it back to idle very quickly which would usually cause the engine to start running the correct way again, this may not work with heavier petrol engines though

check and reset your points, give your carb a clean, replace your reeds and spark plug/HT cap and lead

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i have a dt125lc that has an intermittent fault which is sometimes it starts and runs fine but other times it starts very lumpy and keeps cutting out then backfires,i have cleaned out the carb but it made no difference

when it is just about running it wont rev up then cuts out and backfires,also i am not sure but i had the cover off the left side of engine and the stator wheel spins when its struggling to run then when it cuts out the wheel spins the opposite way and if you still have kick start down it kicks back up

any ideas guys

Hi & :welcome: to the forum

you dont state the age of the bike but if its an early 80's model it sounds like you have a pulse coil on the way out

Regards Jim

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hi jim thanks for the welcome you say it sounds like a pulse coil can you tell me is that the coil mounted under the tank with 1 wire or is it something in the engine behind the stator wheel

ok i have had another look at the bike which is a c reg 1985 dt 125lc,i have checked and cleaned the reeds which wasnt that bad,trying to kick the bike over and it is definately bouncing back the other way as i nearly had my foot broken when it kicked back and the last time it kicked back so hard the kickstart has gone past it stop point and is sitting on the casing so i now have to take the caseing off to see whats broken in there.i have a spark at the plug and petrol yet it will run rough for a second then kick into reverse

any ideas guys as this is driving me mad

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Hi & :welcome: to the forum

you dont state the age of the bike but if its an early 80's model it sounds like you have a pulse coil on the way out

Regards Jim

hi jim

thanks for the welcome

the bike is a c reg 1985 dt125lc ,can you tell me where the pulse coil is ? is the one under the tank with one wire or is it in the engine under the stator wheel somewhere.The engine is definately kicking into reverse as it has now broke the kick start which has gone back too far and sits on the caseing i dont understand how an engine can change direction

thanks for your help

dave

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hi jim

thanks for the welcome

the bike is a c reg 1985 dt125lc ,can you tell me where the pulse coil is ? is the one under the tank with one wire or is it in the engine under the stator wheel somewhere.The engine is definately kicking into reverse as it has now broke the kick start which has gone back too far and sits on the caseing i dont understand how an engine can change direction

thanks for your help

dave

Hi Dave,

the pulse coil is in the mag and feeds the red/white wire. If this small coil get confused the timing will always be out ... the part number you would need is 3M2-85580-20. The reason the engine striking back is due to the ignition timing being incorrect. Wait till you get a big 4 stroke single :lol:

Regards Jim

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Hi Dave,

the pulse coil is in the mag and feeds the red/white wire. If this small coil get confused the timing will always be out ... the part number you would need is 3M2-85580-20. The reason the engine striking back is due to the ignition timing being incorrect. Wait till you get a big 4 stroke single :lol:

Regards Jim

hi jim

pulse coil that sounds right do you know where to get one as i have searched but not found anything for my bike

thanks for your help

dave

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