Bike wont keep motor running

[Watts]

Hey guys I have a 80cc motor on a Pacific Coast Chopper bike. When I purchased the bike the fellow said I may need to replace the spark plug soon. I have taken the bike 300km, and just yesterday while riding it going to make a turn the bike sputter and the motor kicked off. I tried starting the bike numerous times and the motor would start each time but not get going. I have a engine with a clutch setup and choke on the motor.

I tried opening the choke and still no success in getting the bike going, the motor starts each time but wont start pulling the chain, the engine cuts out after 5 seconds, once engine is started holding clutch wont keep it running either. Is it most likely that I need to replace the spark plug on the bike

Thanks For Any Help

Watts

 

[ferball]

It sounds more like a carb problem than a spark plug issue, spark plug is easy enough to check pull it out and see how dirty it is.

 

[Watts]

I am all new to this and know where little about motors. Is there an avialble diagrams or videos that show how to clean the carbÉ

Thanks for all the help

Watts

 

[Watts]

I checked the carb and it was clean as a whistle, no build up no oil nothing. Any other ideas what it might be that is stopping the bike from moving. The motor starts but dies after about 5-10 seconds, holding clutch wont allow engine to idle. Checked carborator and also replaced spark plug. Any other ideas

Thanks

Watts

 

[Mac]

Watts,
After you perform the other suggestions offered, check for good fuel flow from the tank, the petcock screen may be clogged, check the CDI wire connections, sometimes engine vibe can short the wires to the frame or against each other, the Chinese insulation is quite poor. Change spark plug wire if original is stock, they are poor quality(not likely the problem) It really sounds like a fuel problem to me too, check the fuel inlet nipple on the carb. take it out and look for dirt, make sure to tighten it back. Check(change) intake gasket and carb. clamp integrity. Does the engine run with various degrees of choke applied?? Did you mix the fuel properly, no more oil than 32:1. Is the gas you mixed old, contaminated, water? Check for compression leak on the head gasket(see any oil on the engine) Remove the muffler and start the motor, any difference??(only do this for a short time) Further down the road, maybe you lost a crank seal. Plug gap .025, NGK B5HS or B7HS.
Hope that stuff may help.
Mac

 

[Watts]

Yeah I disconnected the fuel line from where it connects to the fuel filter, and when the gas switch is on the gas flows freely from the tank through the line. I have a little valve situated close to the carb that when I push it in (spring coiled to pop back out) gas leaks from the motor. This valve is located directly on the side of the carb which is after the fuel line and fuel filter so does this mean the fuel filter and line are getting the gas to the carb fine.

If so what else could it be. I tried running it again today and it spins the chain for about 5-7 seconds and just shuts off, still wont idle while holding clutch in...I have tried biking really far and fast to ensure wrming the motor while the choke is up and still nothing but that 5-7 second momentary humm of the motor.

I also just noticed after unscrewing the 2nd hose that connects to the other end of the gas filter and directly to the carb...and noticed a tiny pointed piece of metal in the hole where the gas goes into the carb. Should this pointed (like a tack) piece of metal be in the carb hole where the gas line connects in. It is near impossible to remove that little piece even with pliars and a high powered magnet.

P.S Mac I have been using 20:1 ratio Octane to Oil..I will start using 32:1.

Thanks for all your helps people!! Great to have this forum around for us neewbies!

 

[Venice Motor Bikes]

When the other guys said to clean the carb; you're not gonna find oil or dirt all over the inside.... They meant there's a little speck of dirt somewhere in the fuel inlet, or in the jet that's blocking the fuel flow to the engine.

Go back & re-check it.

 

[Watts]

I have checked the carb again and can only see a few things. None of which have any dirt or build up. I have the bracket arm that is connected to the floater (tack looking thing) that seems to adjust the gas flow to the carb, the bracket and tack are clean as a whistle.

There is a big center pin in the middle with a hole , that is clean as well. There is also a hole that goes to the back of the carbs filter and that is clean as well. I have included some pictures as well.

It seems the carb is fine unless I am missing something which would be hard as this is a simple component (I have included pictures). And other ideas why my bikes motor would start and turn off after 5-7 seconds.

I start the motor its starts running each time pulling the chain for about 5-7 seconds then the motor shuts off. I have tried using the clutch to idle the motor but the motor turns off.


Any ideas please need some help !!! PLEASE HELP


Thanks

Sean

 

[Bikeguy Joe]

Once it starts, push the choke down to half or less ad work the throttle a little.

 

[Watts]

Nougat, the float needle where the gas line comes into the carb is fine, goes up and down with ease. I removed the main center screw that went over the pin, I notice that I can push the pin in a wee bit with a decent push of the fingers need to apply some force). Should i just clean the screw itself or is there a way to remove the pin that the screw was covering and how much resistance should that pin give me when i look to push it in a bit

Pin looks clean, and screw piece that fits over pin is clean as I can see through the larger hole out the other side of the tinier hole, also when i blow through the screw I feel the air comming out the other end (hole).

I also noticed a screw with a spring on the outside of the carb, I can turn the screw clockwise which makes it go into the carb more, and counterclockwise makes it come out...what is this screw with sprin for on the carb.

Included some pictures of the center screw in piece that covered the pin, and the carb with the pin, thanks

Bikerguy Joe, I have tried starting the motor with the choke in the fully upright position, fully down, half way, quarter way etc. No matter where I have the choke set it still wont keep the motor running. Any other ideas, thanks.

Watts

 

[Watts]

Nougat, there are 3 pin looking things in the carb. First is the main pin in the center that has a housing that can screw off....this is clean as heck.

Number 2 is the float valve needle (tack looking thing) where the gas tube comes into the carb. That floating pin (tack looking thing) moves up and down with ease and has no build up.

The 3rd is the pin that connects to the the push button that allows gas to leak out of the carb filter. And it just has a lock pin to keep it in place, but the valve pushes in and out and the `clip`on the inside of the carb is clean and moves up and down while pushing in the valve.


What and where is this, i have nothing situated on the bottom of the carb that has a long tube. All tubes connect to top of carb from outside.

```What's probably dirty is the main jet, that screws into the long tube at the bottom. Take both of those out, and unscrew the little jet from the tube. What and where is this, i have nothing situated on the bottom of the carb that has a long tube. All tubes connect to top of carb from outside.``
`
Thanks

Watts

PS Seems carb is clean and everything in it, what else could this be. Know something else, cuz these carb ideas are cool but not working, and carb looks clean...or do I need a proton microscope to see this supposed dirt buildup. What else could this be!!! Please help

 

[Venice Motor Bikes]

I said it in my first post; you're not looking for any dirt 'build up'... You're looking for ONE TINY SPECK of dirt that could be clogging the inlet needle or the main jet.
If there's still nothing... try looking for any air leaks in the intake or carb area.

Also... how much oil did you mix into the gas? & what's the plug gap?

 

[Watts]

Yeah I understand that, basically anything that may clog air or gas going through. And all the holes and openings are clear. I have been using a 20:1 gas oil ratio. Ive been told to use 32 to 1.

How do I determine the plug gap. I dont see any holes on the carb but a hole could be tiny and unoticable by the eye, how do i check for air leaks in the carb and intake.

And just so I am clear the inlet needle is the needle (golf shoe spike looking thing) that goes up and down based on the amount of gas in the carb..it is the needle that sits in the little hole (opening) where I connect my gas line (tube).

What is the main jet and what does it look like, and what is the main needle (that has a screw on housing) that connects to a cable that goes to the clutch.

Thanks so much for the help and input, and patience with a neewbie guys!!


Watts

 

[Venice Motor Bikes]

Read these... Norman's threads are pretty good!
http://motorbicycling.com/f39/motorized-bicycle-carburetor-install-rebuild-302.html
http://motorbicycling.com/f39/ngk-spark-plug-info-13089.html
http://motorbicycling.com/f39/installing-carburetor-manifold-your-motorized-bicycle-303.html

 

[Watts]

I have taken apart the carb and submersed it in hot water for awhile and ran it under hot water. Made sure to dry it off full and ensure all holes are not clogged. Here are some pictures

 

[Watts]

Hey guys reconnected cleaned out carb on bike and gave it a run..alas same thing. This time however the engine starts and goes for 15-20 seconds then turns off cuz its waiting for gas. Holding the clutch will not allow the motor to idle. I did notice however that the throttle (hand shifter) is loose and and when i push the kill motor switch while the motor is going it does not shut off the motor.

Any ideas, does this sound like a wiring issue, is there a way to determine if there is a short in the current wiring setup. The brake style cable connected to the throttle and the carb is loose on both ends, but it isnt screw in ends so how do i tighten the cable to the carb hole and also to the hole on the right handlebar throttle.

Thanks

Watts

 

[Brent436]

maybe i dont completely understand the problem, but does the bike run when you give it a bit of throttle and just wont stay running at idle? if so, maybe your idle screw came out a bit. i know it sounds stupid and a longshot but its happened to me before. just trying to help haha. good luck!

 

[Watts]

Brent436. The engine starts after peddalling abit to warm it up, problem is that the engine wont stay running for longer than 10 seconds. When the engine starts it is only slowly pulling the chain and normally I would turn the throttle to get the bike moving.

When i turn the throttle while the motor is going it does nothing, also attached to the throttle is a kill switch than when pressed turns the motor off immediately. When I push this kill switch it does not turn the engine off. Also when I start the engine and push the clutch to idle the bike, the engine turns off after 7-10 seconds of idling.

I have cleaned my carb fully, check my gas flow to the carb and seems fine. I am guessing that it may be a lose connection in the wires that come from the throttle to the carb, or the little black electrical box.

Any ideas how to check the electrical side of things to ensure its working or what need to be replaced?

Thanks

Watts

 

[Brent436]

i know when i first put my motor on my bike (48cc Grubee Skyhawk) it wouldnt run for more than a few seconds before it would sputter and die. i ended up fixing this by closing the gap on my spark plug so maybe try that to see if it works.

MAYBE your kill switch is shorting out and thats why its dying, but that seems unlikely since its starting. you can check this by disconnecting the 2 wires that come from the throttle (it should be one grounded to the frame of the bike and one to the group of wires coming from the magneto). by disconnecting those 2 you eliminate the killswitch from the equation. if it runs, thats your problem. if not, then the killswitch is fine.

im sure your probably sick of hearing things about the carburator, but maybe try adjusting your float height? im not sure if anyone told you to or not but i figure id say something just in case. you adjust the float height by slightly bending the arms that the float pushes up on to close the flow of fuel. bending the arms down will lower the float height, and bending them up will raise it. possibly try bending them up very slightly. if fuel starts leaking out of your carbs air filter after you do this, youve bent them too far. to fix that just bend them down a bit.

i dont think it would be an electrical problem but just to make sure, pop off the magneto cover. its only 4 screws so its worth checking without too much hassle. the magneto cover is the cover towards the front of the bike on the left hand side. just pop the cover off and make sure theres nothing shorting out and that the wires are still solidly connected.

check these things and get back to us. my money would be on the spark plug gap but with these little chinese motors it could be anything haha. good luck and i hope this helps.

-Brent

 

[Venice Motor Bikes]

Do you think it's starving for fuel, or getting too much fuel???