Struggle with 125cc dirtbike.

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benox

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Hey there,
Im kinda new to these forums so bare with me. First of all, I recently got a 125cc dirtbike from a place called Redback Imports in thomastown,victoria. I was trusting in this shop to provide me with decent quality bikes that wernt going to break down every 5 seconds. My friend had bought a bike from there and had it for one year. Only problems he ever had was the gear stick snapped, accelerator cable snapped. So assuming my bike would have no problems for a couple of weeks I bought the bike on christmas eve road it around for about 2 hours. I was very happy it was running great. I took it down to the park kept riding.. anyway about 2 days later my friend and myself went up to ararat (bout a three hour drive) to a block of land in which we could ride our bikes from morning to dawn. I got on my bike road it around for about 2 hours. The bike started sputtering then it died. I tried to electric start it and smelt this burning coming from the back of the bike. I stopped look at the bike all the wires had burnt out. Anyway the bike cost me originally 850. So I had to spend 3 days in ararat with a bike that wouldnt move. We took it to a place called Epping Bikes. They assessed the bike and found what the problem was. The CDI had blown and needed to be replaced. So i further spent 130 replacing the cdi and the labour involved. Ok I was really excited because we were going to take it away again to a place called avoca where my grandparents own a massive block of land. We get up there took about 2 hours to get there when we got there me and my mate aiden started riding around for about 2 hours. We are riding down about a 300m straight. Im in fourth with the throttle pulled back to the max going as fast as possible the bike starts making this sputteirng.. Im in fourth and the bike just went FRRRRRRRRrrRrrrrrrr...r... and cut out. I spent about half an hour standing there trying to kick start it.. It just wouldnt start we got a mechanic over who didnt have a clue what was wrong with it so we took the bike back to melbourne. My friends dad knows alot about motorbikes and started testing some of the parts. He tested the spark plug, carby, compression fuel, cdi, wiring, magneto.. everything he knew how to test. Everything was fine. We went and got a new carby in hope that that would be it. We put it on and gave it a few kicks. Still wouldnt go!!! to this day about a month later the bike still hasnt been fixed.. I really dont have enough money to take it back to epping bikes.. If any of you have any ideas what the problem is please hlep!!
 
so have you got spark, did you take the spark plug out plut it in the cap and hold it against the engine while kicking it over to see of it was actually making a spark?
engines are pretty simple all they need to run is:
spark
fuel and compression
its most likely the spark
then the fuel and if it has comp when u kick it over then it wont be that
id try the spark first
 
Shouldnt of bought a MXB copy, MXB's already being the worst bike known to man to come from china and just copying it is asking for trouble, cant believe you paid $850 for it they sell for just under 400 on ebay, I laugh at your stupidity, ( and the colour of your hair ) Chuck it out and go get a decent china bike, ( and a decent mecanic )
 
so have you got spark, did you take the spark plug out plut it in the cap and hold it against the engine while kicking it over to see of it was actually making a spark?
engines are pretty simple all they need to run is:
spark
fuel and compression
its most likely the spark
then the fuel and if it has comp when u kick it over then it wont be that
id try the spark first


Dude we even bought a spark plug tester, and tried the spark blug in another bike the spark plug is working 100%

Although we havent got a compression tester yet but we took the spark plug out jammed my finger in the hole where the spark plug was a gave it a kick it sucked my finger in. My friends dad says this shows that there is compression. Also when i try to kick start it.. The bike sounds like its about to start the engine is turning over but it just doesnt.. really annoying!!

Also we tried to roll start the bike .. it really sounds like its about to start but then again it might not be. When we try to roll start it it sounds like Frr frr frr frr frr fr f f ..
 
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Dude, you want it fixed its quite simple, Once you fry a C.D.I you fry the hole wiring, and a bike with electric start is just asking for trouble, Rip all the electric start gear off Gives the bike atleast 4-5% more power less strain on engine because the electric start pully is moving when engine is running, rip all the electric start wiring loom off, and go buy brand new loom ( 20-30 ) fit it -minus the electric start part of the wiring and your problem will be solved 100%
 
Frank bro, The shop in epping redid all the wiring and steve took the battery off I dont use the electric start anyway the bike died after the battery was taken off
 
The spark plug is OK. This does not mean that you HAVE SPARK. Test the plug by holding it against the head and giving it a kick.
 
thats what i was trying to get at
it does sound like theres not spark even though the spark plug is fine just trace it back to where the problem is i would try at the coil first then the look at the sensor on the flywheel and also the cdi also check that all the wires are fine
 
my guess if it isnt the sparky maybe the jets are blocked have you checked them ?? new bikes casn get bits of plastic from the tank stuck in the jets
 
If you have trouble holding the spark plug you can use a jumper lead one end connected to the head and the other end connected th the spark plug tread while you kick it. This is what I do as i have had a few shocks (I know this is soft) but it makes it easy.
 
The spark plug is running fine.. We've tested it and you can see spark also the spark tester shows when you kick it bolts of electricity go through this glass thing if there is spark and that is what happened when i kicked.. where are the jets ?
 
The jets are in the carbi. you just unbolt the carbi from the maniflod undo the four bolts to take the bottom of the carbi off(bowl) and removing the jets with either a screwdriver or a spaner and give them a blow out with compreesed air. Also check you don't have any kinks in ya fuel line, it will stuff you up every time.
 
alright thanks m8, when i get home ill go have a test on the jets.. About the fuel line.. There is a sortive tube that goes from fuel tank to carby i dont know if thats the fuel line but sometimes when u turn the fuel on.. the is an air bubble in the tube i dont know if that is a problem but anyway.. Well anyway ill try
 
ok well, tried checking the jets they arnet blocked.. fuel line is fine checked if the fuel was contaminated,, checked all the wiring under the seat and under fuel tank.. still cant find the problem!! helppp
 
anyone? please help ive had this bike for 3 months and got about 2 hours ride out of it!!!
 
Sounds like it isnt getting any fuel or it isnt getting any air.

The spark plug should be light brown if its any other colour like black then the mixture is wrong.

My friends bike had the same problem, we cleaned the air filter, cleaned the spark plug, adjusted the mixture and gave it new oil and worked fine, it even had about 50% more power!

You don't need a spark plug tester just hold the spark plug with plyers, kick it over, and you'll see the spark.

Anyway, sorry to hear your bike broke down like that you shouldve spent $850 on somthing a bit better and better value like a pitpro.
 
Also, try starting it without the air filter, other than that I don't know whats wrong...
 
hmmm sounds like i would take it back to where you got it from and tell them all the probs you had if they wont help you get an MSO good luck
 
hmmm sounds like i would take it back to where you got it from and tell them all the probs you had if they wont help you get an MSO good luck


Trust me mate i would, the guy i bought the bike off is the dodgiest fucking retard he takes no responsibility for the shtity bikes he sells.. thats why we had too take it up with consumer affairs...
 
How can you change the amount of air getting in? We also tried moving in the idle speed up and down trying to kick start it about 180 times.. still wouldnt go
 

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