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Old 02-06-2017, 10:04 PM
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Default 50cc quad wont start

Morning guys want to start by saying what a great site, endless amounts of usefull information so im hoping some one can help me out.

Please forgive me, for my first post this is going to be rather long winded but i want to be as detailed as i can.

I was given a small 50cc chinese quad by my brother, he said his kid was out on it and it just cut out and wouldnt start again.

we dont know the manufacturer of the quad

He discovered there was no spark and it has sat in his shed for about 18 since, i am by no means a mechanic but in my younger days i had a kx250 which was my pride and joy and i tinkered with it rather a lot.

the quad has electrical issues but my main concern is why the engine wont start, ill sort the electrics out once i know the engines good.

ok so lets start, ill try and bullet point the issues and what ive done to make for easier reading

ISSUES

1- no spark, i did resolve this issue
2- dead ignition, nothing on the turn of the key-issue ongoing

WHAT IVE TRIED

A 1- i replaced the spark plug, still no spark
1.1 i replaced the ht lead, no spark
1.2 i replaced the CDI unit no spark
1.3 New battery
1.4 i replaced stator magneto and i finally got a strong consistent spark.

A 2- i Disconnected all the wire harness and cleaned all contacts, nothing
2.1 ive disconnected the kill switchs nothing


thats pretty much where i am but heres a few more obsivations and things ive done

its got a good new battery

i have removed and cleaned the petrol tank and filled with fresh petrol

i have removed and cleaned the carburettor

i have removed the inline fuel filter and replaced

i can see a good strong spark from the plug

if i place my thumb over the spark plug hole i can feel good compression

i have bypassed the key ignition and disconnected the kill switch's

im trying to start the engine directly by shorting the possitive connection on the solenoid, this is the only way i can get the quad to crank


I have tried every thing i can think off to get the engine started but it just wont fire so any suggestions are more than welcome

sorry for the messy post but i have tried to be as detailed as possible with out writing jibberish

ps its electric start only, no kickstart, 4 stroke automatic
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Old 02-08-2017, 03:42 AM
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Regarding the starter, most have a lock-out, requiring a brake to be on before the engine can be spun on the starter, did you do this? If yes, you have to go through the system, see my posts in the Chinese Quad section yesterday and today (Solenoid problems).

You may still have dirt or water in the carb, but try engine start fluid down the air intake, (I prefer gas from my gas blowlamp). If you can get it to fire on that, you probably have a carb problem. Does the choke work?
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Old 02-08-2017, 04:55 PM
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Quote:
Originally Posted by merryman View Post
Regarding the starter, most have a lock-out, requiring a brake to be on before the engine can be spun on the starter, did you do this? If yes, you have to go through the system, see my posts in the Chinese Quad section yesterday and today (Solenoid problems).

You may still have dirt or water in the carb, but try engine start fluid down the air intake, (I prefer gas from my gas blowlamp). If you can get it to fire on that, you probably have a carb problem. Does the choke work?
hi merryman, thanks for your response, my quad does infact require the break leaver to be engaged before the engine will start however when i was troubleshooting the no spark problem i disconnected all electrical systems besides those required to get the engine running.

regarding the carb i have taken it off, cleaned it, check the floats are not sticking and blown the jets out.

i have tried spraying easy start into the air intake but it still wont start. i have even tried a drop of petrol in the spark plug socket.

so just to clarify things heres where im at

im bypassing the entire electrical system and shorting the solenoid to start the engine.

i have good spark

good compression

it just wont fire

thanks again merryman
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Old 02-08-2017, 05:12 PM
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Default timing

sorry i forgot to ask, when i was trying to fix my spark issue i replaced the magneto stator could be possible i knocked the timing out??

thanks rich
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Old 02-09-2017, 03:31 AM
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You still don't mention the choke. Most modern stators are fixed, so that the timing is set and can't be altered, but you don't mention make so I guess yours could be adjustable. Was the old stator identical to the new one? As the trigger coil has to be in exactly the same place. It is worth getting the compression checked, as anything less than 90 psi can lead to poor starting.

You will have to get the wiring hooked back up to get the rest of the electrics to work
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Old 02-09-2017, 03:54 AM
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Quote:
Originally Posted by merryman View Post
You still don't mention the choke. Most modern stators are fixed, so that the timing is set and can't be altered, but you don't mention make so I guess yours could be adjustable. Was the old stator identical to the new one? As the trigger coil has to be in exactly the same place. It is worth getting the compression checked, as anything less than 90 psi can lead to poor starting.

You will have to get the wiring hooked back up to get the rest of the electrics to work
Sorry merryman I'm not sure of the make, I know it was manufactured in 2011 though. I took the stator to a local bike shop who had the exact same stator for 35 the only difference was the bracket it was sat on was slightly larger, the bloke said it was for a pit bike but the actual stator is the same so I removed it and used the original bracket, I assumed the stator fix was fine because before I switched it over I had no spark, with the new stator in I have a good solid blue spark.

When you ask about the choke working I'm not quite sure what you mean, when the carburettor is off the quad, yes it seems to operate fine, I can see it opening and closing but if you mean does the quad start when chokes on then no it doesn't.

I don't have a compression gage to test but I could always pop to Halfords and buy one for 40 if you think it will help?

Would it help if I were to make a short video showing what's happening?

Thanks for all your help pal really appreciate it

Rich
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Old 02-11-2017, 08:01 AM
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As you are writing about and Halfords, I guess you too are in the UK. Paying 40 for something you may not use again seems excessive, I got a Honda 70 motorcycle (almost identical engine) to "check over" before becoming someone's Christmas present, it had no compression, but still ran, so these engines are not too troubled by low compression. Some chokes are cable operated and can stick, some are electrical and can fall apart inside, it seems yours is OK. I'm not a great fan of on-line videos, it may be time to get that local bike shop to take a look at it.
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Old 02-11-2017, 03:09 PM
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Quote:
Originally Posted by merryman View Post
As you are writing about and Halfords, I guess you too are in the UK. Paying 40 for something you may not use again seems excessive, I got a Honda 70 motorcycle (almost identical engine) to "check over" before becoming someone's Christmas present, it had no compression, but still ran, so these engines are not too troubled by low compression. Some chokes are cable operated and can stick, some are electrical and can fall apart inside, it seems yours is OK. I'm not a great fan of on-line videos, it may be time to get that local bike shop to take a look at it.
correct, sunny mansfield, nottinghamshire to be exact, any way my brothers just been round with his compression gage, its only reading 45 and from what i can see on the internet it should be about 150psi?

i could just take it to the shop but i like the challenge of trying to fix things myself and the shop really is the last resort.

could such low compression be caused by loose valves or is it going to be the piston ring?

i have found a full kit on ebay with piston, ring, oil ring and gaskets for under 20 so not too expensive
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Old 02-14-2017, 03:54 AM
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I fitted one of those kits to the Honda, good quality for the price, though all machined parts of the cylinder had sharp edges. Try setting the valves first, not certain what they should be, but 0.003" should restore compression if that is the problem.
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