anyone know anything about 4 stroke scooter engines

pauls0701 · May 11th, 2011, 20:27

i brought a sym joyride 180cc scooter about a month ago and all was going well untill yesterday when on way home from work it just cut out on me and wouldnt re start.

i have checked the following
spark, good strong one
fuel, double checked this by squirting some easy start in the carb,
checked the cam timing. spot on.
compresion. not go a compresion tester but put finger over spark plug hole and there seemed plenty there.

anyone got any ideas what else i can check as brought this to save some fuel money traveling to work and it stands me at £600 so need to get it running else i could have just used the car for the next year and been just as well off

scottishvolvo · May 11th, 2011, 20:44

I'll be interested in replies here as well. Not got any problem yet but handy for the future.
How do you like the Sym? I've had a Shark 125 for about 3 months now and still love going out on it.
I've recently signed up here for advice. http://www.twistngo.com/userforum/index.php

I hear talk about CDi units failing, I think that is to do with ignition, plenty available on E-Bay. I've already used a guy for spares and he was great.. ricky2stroke.

pauls0701 · May 11th, 2011, 20:53

was loving it untill yesterday lol its now doing my head in as it should be so simple. thanks for the link will sign up and see what they have to say.

have also heard a lot about the cdi unit but does seem like a very strong spark but that said it is with the plug out so could be failing when under presusre will have a look and see if i can find a cheap one to try

tommy t4 · May 11th, 2011, 21:18

sounds like to me the injector on the inside of the carb has got deposites stuck, needs to be striped (jus the carb) and the brass injector blown thru....but dont lose the float in there or the tiny metal bracket...

Volvo Nick · May 12th, 2011, 11:53

just a thought, have you checked the lead from the crank position sensor? All well and good having a spark but if it is happening at the wrong time it is as good as useless. Good luck!

pauls0701 · May 12th, 2011, 19:28

Quote:

Originally Posted by tommy t4

sounds like to me the injector on the inside of the carb has got deposites stuck, needs to be striped (jus the carb) and the brass injector blown thru....but dont lose the float in there or the tiny metal bracket...

defo have fuel coming though and have tryed squirting easy start in to the air intake on carb so fairly sure that not the problem

pauls0701 · May 12th, 2011, 19:33

Quote:

Originally Posted by Volvo Nick

just a thought, have you checked the lead from the crank position sensor? All well and good having a spark but if it is happening at the wrong time it is as good as useless. Good luck!

it got a pick up in side and if that or the wire to it wasnt working it woundnt spark at least i dont think it would.

plan for tomorrow is to buy a new spark plug in case its not working under presure

have double checked the valve timing and that is spot on cant check the ignition timing as dont have a timing light but acording to the manual that is set and cant be changed.

running out of ideas now and if the spark plug dont work i think it could be going to the great scrap heap in the sky.

also checked the rings today and there is no problem with them.

tommy t4 · May 12th, 2011, 19:43

mate doesnt matter if you spray anything in the carb if the injector is blocked, its blocked, easy start wont get rid of that, its a pin size hole in the injector and anything could block them, you need to take it apart and blow thru in the opposite direction that the fuel travels in......

pauls0701 · May 12th, 2011, 19:48

Quote:

Originally Posted by tommy t4

mate doesnt matter if you spray anything in the carb if the injector is blocked, its blocked, easy start wont get rid of that, its a pin size hole in the injector and anything could block them, you need to take it apart and blow thru in the opposite direction that the fuel travels in......

ok will go and get the carb off now and see what i can do thanks

scr8pdo · May 12th, 2011, 19:49

If you got fuel and a spark and compression it should fire, unless the valve timing is out or valve stuck shut ie not letting fuel in, if it dont fire on easy start you know you can eliminate fuel, i would sniff the exhaust after a fair bit of cranking see if you can smell unburnt fuel, this would indicate its getting in and out, try also drying the plug on a hot stove or a blow lamp, under compression it might not be firing in the right place and shorting in the nose, also see what colour plug is, is it wet, dark, light and dry etc?

I used to race bikes and you would be suprised what can go wrong with a spark plug, check the gap too, if its too big it will arc ok when not under pressure but air is an insulator and under compression there is more dense air between the electrode and the earth, it will take an easier route maybe inside the plug nose

May 11th, 2011, 20:27	#1
pauls0701 Member Last Online: Oct 12th, 2015 19:22 Join Date: Aug 2010 Location: swindon	anyone know anything about 4 stroke scooter engines i brought a sym joyride 180cc scooter about a month ago and all was going well untill yesterday when on way home from work it just cut out on me and wouldnt re start. i have checked the following spark, good strong one fuel, double checked this by squirting some easy start in the carb, checked the cam timing. spot on. compresion. not go a compresion tester but put finger over spark plug hole and there seemed plenty there. anyone got any ideas what else i can check as brought this to save some fuel money traveling to work and it stands me at £600 so need to get it running else i could have just used the car for the next year and been just as well off

May 11th, 2011, 20:44	#2
scottishvolvo Premier Member Last Online: Nov 17th, 2023 00:15 Join Date: Dec 2004 Location: Glasgow	I'll be interested in replies here as well. Not got any problem yet but handy for the future. How do you like the Sym? I've had a Shark 125 for about 3 months now and still love going out on it. I've recently signed up here for advice. http://www.twistngo.com/userforum/index.php I hear talk about CDi units failing, I think that is to do with ignition, plenty available on E-Bay. I've already used a guy for spares and he was great.. ricky2stroke. __________________ Chris '98 S40 2.0T..Gone. 2000 S40 2.0 SE Auto and loving it. 2014 V40 Cross Country Please consider registering with the Anthony Nolan Trust, you could save a life. Last edited by scottishvolvo; May 11th, 2011 at 20:47.

May 12th, 2011, 11:53	#5
Volvo Nick Adventurer Last Online: Dec 10th, 2014 22:36 Join Date: Dec 2010 Location: Suffolk	just a thought, have you checked the lead from the crank position sensor? All well and good having a spark but if it is happening at the wrong time it is as good as useless. Good luck! __________________ Me: 99' C70T GT 2.5T (Auto), 01' V70 T5 EST (Auto), 89' 760GLE 2.8V6 (Auto) (SAL) Family: 99' V70SE 2.5T (EST), 92' 940 Wentworth 2.0T (EST), 92' 440 1.8, 89' 340 1.7, 87' 740GLE 2.3 (EST), 82' 240GLT 2.3 Visitor Since 2005 :-)

May 12th, 2011, 19:49	#10
scr8pdo Premier Member Last Online: Aug 27th, 2016 13:21 Join Date: Dec 2008 Location: Greater Manchester	If you got fuel and a spark and compression it should fire, unless the valve timing is out or valve stuck shut ie not letting fuel in, if it dont fire on easy start you know you can eliminate fuel, i would sniff the exhaust after a fair bit of cranking see if you can smell unburnt fuel, this would indicate its getting in and out, try also drying the plug on a hot stove or a blow lamp, under compression it might not be firing in the right place and shorting in the nose, also see what colour plug is, is it wet, dark, light and dry etc? I used to race bikes and you would be suprised what can go wrong with a spark plug, check the gap too, if its too big it will arc ok when not under pressure but air is an insulator and under compression there is more dense air between the electrode and the earth, it will take an easier route maybe inside the plug nose __________________ SAAB 9-5 HOT Aero Audi A4 1997 TDi Avant (old smoker!) Iveco Turbo Daily Recovery Lorry

May 11th, 2011, 20:53	#3
pauls0701 Member Last Online: Oct 12th, 2015 19:22 Join Date: Aug 2010 Location: swindon	was loving it untill yesterday lol its now doing my head in as it should be so simple. thanks for the link will sign up and see what they have to say. have also heard a lot about the cdi unit but does seem like a very strong spark but that said it is with the plug out so could be failing when under presusre will have a look and see if i can find a cheap one to try

May 11th, 2011, 21:18	#4
tommy t4 Premier Member Last Online: Jul 10th, 2021 22:47 Join Date: Mar 2011 Location: gravesend kent View Photos By: tommy t4	sounds like to me the injector on the inside of the carb has got deposites stuck, needs to be striped (jus the carb) and the brass injector blown thru....but dont lose the float in there or the tiny metal bracket...

May 12th, 2011, 19:43	#8
tommy t4 Premier Member Last Online: Jul 10th, 2021 22:47 Join Date: Mar 2011 Location: gravesend kent View Photos By: tommy t4	mate doesnt matter if you spray anything in the carb if the injector is blocked, its blocked, easy start wont get rid of that, its a pin size hole in the injector and anything could block them, you need to take it apart and blow thru in the opposite direction that the fuel travels in......

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