Have spark and fuel, but wont start

[BrandonG]

My 80 cc Bikeberry 2 stroke stopped working about a month ago, so i put it up until today. I put a new plug on and a lawn mower plug wire and it ran! I was so a happy. I test rode it for 5 min, parked it, then rode a few miles a while later, went in a store, then wouldnt start when i tried to head home. Has fuel, Petcock is open, no clog in the line (took off carb and gas poured out). I tried disconnecting the kill switch but still nothin. Unscrewed spark plug and pressed against engine while riding. nice fast consistent sparking (except for a few seconds in the middle, but im 75% sure that was me not holding it down while pedaling). Im on my last tank for break in (2 gallons used so far) at 24:1 oil. I know the carb isnt stuck shut or wide open cause i can open it up while pedaling the engine and there's a clear noise difference. Any advice on what else to check?

 

[fatdaddy]

My 80 cc Bikeberry 2 stroke stopped working about a month ago, so i put it up until today. I put a new plug on and a lawn mower plug wire and it ran! I was so a happy. I test rode it for 5 min, parked it, then rode a few miles a while later, went in a store, then wouldnt start when i tried to head home. Has fuel, Petcock is open, no clog in the line (took off carb and gas poured out). I tried disconnecting the kill switch but still nothin. Unscrewed spark plug and pressed against engine while riding. nice fast consistent sparking (except for a few seconds in the middle, but im 75% sure that was me not holding it down while pedaling). Im on my last tank for break in (2 gallons used so far) at 24:1 oil. I know the carb isnt stuck shut or wide open cause i can open it up while pedaling the engine and there's a clear noise difference. Any advice on what else to check?

Hey Brandon, Could be a plugged jet. Take the carb bowl back off, unscrew the jet tube and blow it out. (The brass tube hanging in the bottom center of the carb.) You'll see it when you get the bowl off.
You didn't say if you were using an inline filter or not. The new tanks get paint chips knocked off the top where the cap twists on. It winds up in the carb every time, plugging the jet.
Get a inline filter, It's a MUST.
fatdaddy.
IT'S YOUR BIKE, BUILD IT YOUR WAY.

 

[userful]

Be leave or not You need to change the magneto coil, even if you have spark,
probably is to poor it is not enough to make explosion in the cylinder.

 

[fatdaddy]

Be leave or not You need to change the magneto coil, even if you have spark,
probably is to poor it is not enough to make explosion in the cylinder.

NO NO NO. There are a lot of things to do before ordering a new coil. And this is from the guy that ALWAYS thinks IT'S THE COIL. A coil can go out like that, sure, but a new tank always has trash in it from the factory. AND paint chips ALWAYS, EVERY TIME, get into the fuel system plugging the jet. Lets find out if he can fix it for FREE before advising him to start spending money on parts.
fatdaddy.
IT'S YOUR BIKE, BUILD IT YOUR WAY.

 

[BrandonG]

Thanks for the advise!!!
I went and cleaned the jet- a little bit of stuff but not much, I have the little filter that goes on the petcock. Still wont start tho, not even the pop of an occasional firing.
Might be the magneto. I leave the bike outside and I know rain can get in if not waterproofed like mine is. I tried to open it up when I first got it but the screws are so tight I couldn't budge them with my good screwdriver, So i figured water couldnt get in if I couldn't. Maybe I can use a ratchet set with a bit on the end. Any way to test the magneto without replacing it and seeing if it fixes it? I hate throwing new parts and crossing my fingers. Can get expensive quick!

 

[Norman]

do you set the gap on your spark plug? 0.018 to 0.020 is better than the 0.028 to 0.030 some recommend.

Don't start changing out parts hoping for a cure.

You need 3 things spark at the right time, fuel and air.

Water can get in as water vapor then with temperature changes it turns in to water in side the magneto cover. So if your bike sits out in the weather then you might have a corrosion problem more than likely in the wiring connections.

the strainer inside the fuel tank will stop the large turds but won't stop the fine trash that will clog off the float needle or the main jet.
You have to run a inline fuel filter unless you like pedaling a bunch.

Here's something you can try either a squirt of carb cleaner in the spark plug hole or a little fuel about a teaspoon in the spark plug hole then install the spark plug and try it. If you have carb cleaner you could also give the air cleaner a good shot instead of the shot in the plug hole.
If it pops or starts then you know your ignition system is working, and you have a problem with it not getting fuel.
If nothing happens then try a new cheap spark plug properly gaped 0.018" to 0.020". Make sure you have a spark.

 

[fatdaddy]

The magneto and the coil are two different things. The mag,(spinning MAGnet thing) hardly ever goes bad, the coil(a "coiled" bunch of copper wire) goes bad a lot.
And yeah, If you let it sit in the rain the coil and all the connections could be corroded from condensation. Get that cover off and look at it. The chinese factory does a cold solder connection thats CRAP.
COIL TESTING: (readings are approximate)
Magneto: Use low Ohm-meter scale 200 Ohms
Check Ohms between BLACK and WHITE wire. 2 Ohms
Check Ohms between BLUE and WHITE wire. 300-400 Ohms

CDI TESTING: Readings are approximate.
Use Ohm meter scale about 200-K
Positive lead on BLUE wire and negative lead on BLACK wire infinite (no activity)
Positive lead on BLACK wire and negative lead on BLUE wire. 135-155K Ohms.

Switch to low scale 20K
Measure between spark plug wire and black lead. 2.5-2.7 K ohms.

MAGNETO AND CDI TESTING... Credit goes to 2door.
fatdaddy.
IT'S YOUR BIKE, BUILD IT YOUR WAY.

 

[BrandonG]

I took the air filter off and sprayed WD-40 but it wouldnt fire. The spark plug is a Champion CJ8 that I read on here was recommended, but I didnt adjust the gap. I believe that plug is a .30 gap so Ill try a .20 next. It started twice and ran for a few miles on the new CJ8, would it just stop like that?

When I took off the kill switch I redid the wiring which looks fine. I even crimped it this time and I have a friend who is going to solder it for me this week.

I dont have any of the equipment to test the mag or CDI so hopefully its fixed with the new plug.

 

[wan37]

Try losing the gas cap,and try starting it....

 

[Norman]

WD-40 is not a good starting fluid.
Try starting fluid or carb cleaner.

 

[BrandonG]

Taking the cap off didn't help.

I regapped the plug to .020 and sprayed some actual starter fluid in the plug hole. It started after some pedaling, but ran really rough. I had to keep it reved or it sounded like it would die. Rode it a block the it died at a stop sign after I had slowly let it down idle (idled for 20 seconds, then died) now doesn't start. There is an occasional pop but won't start. Removed plug, sprayed starter fluid and tried again. It fired a few times then stopped. Not sure if the cooler weather (60 here in fl) is making it worse. What's next to try?

 

[BrandonG]

I didnt wanna pedal home so i stopped, let the bike and me cool down, and sprayed starter fluid in and pedaled like my life depended on it. Spits and sputters until finally it could pull me. still running rough and sounding off. im 99% my exhaust gasket is leaking bad but ill just make a new one tonight. Could that have made it not run?

 

[Norman]

exhaust gasket leaking won't cause it not to run or not idle, it will just sound louder if the leak is really bad, or make an oily mess on the front of the engine if just leaking a little.

Are you sure that your choke is off? lever down choke is off. Take the air cleaner off to make sure, if the air cleaner is real oily wash it out in soap and water air dry it and install it with out oiling it.

Is your spark plug wet with fuel? if so then your getting way too much fuel. You can use the starting fluid to clean off the spark plug, spray the electrodes then let it air dry and if you have it blow it dry with compressed air.

Some people have found their main jet unscrewed and laying in the float bowl with a rotten running engine. Have you checked to see if this has happened to your engine? The main jet can also be loose so you will need to put a wrench or screw driver on it to actually check it.

While you have the carb off turn it upside down hook up a short length of fuel line to the carb, using your mouth blow into the fuel line you shouldn't be able to if the needle and seat are working. lifting up on the float lever you should be able to blow through it. DON'T use compressed air for this test.

 

[tooljunkie]

WD-40 is not a good starting fluid.
Try starting fluid or carb cleaner.

actually,wd does work quite well for a starting fluid.but it has to be straight into the back of carb and cranked right away.

the mixed gas in cyl is better,though.

 

[tooljunkie]

as mentioned earlier the fuel filter is a very important part of the fuel system.
i blew out my tank,rinsed it a couple times with acetone and gas.
after running bike for a tank of gas,black stuff was in the filter,i suspect more paint overspray inside tank came loose.some so fine it made it into bowl.

any little lump that makes it into carb will do one of two things,flood engine with a piece of debris caught in inlet valve.
or a piece caught in the tiny main jet.starving it for fuel.

im on the flooding part,as it has spark and wont run.
turn off gas and ride it around with choke off and throttle wide open.
it will take a while to clear flooded crankcase.

put in a dry spark plug and try to start,then pull plug and check it.wet or dry?

 

[Norman]

wd-40 in my book is not a good starting fluid, especially if your having starting/running problems.
it's a mix of very light weight oil, kerosine,and some other things. the most flammable ingredient is the propellant probably iso butane/propane.
but if that is all you have then use it.

 

[fatdaddy]

I took the air filter off and sprayed WD-40 but it wouldnt fire. The spark plug is a Champion CJ8 that I read on here was recommended, but I didnt adjust the gap. I believe that plug is a .30 gap so Ill try a .20 next. It started twice and ran for a few miles on the new CJ8, would it just stop like that?

When I took off the kill switch I redid the wiring which looks fine. I even crimped it this time and I have a friend who is going to solder it for me this week.

I dont have any of the equipment to test the mag or CDI so hopefully its fixed with the new plug.

Spark plug... NGKB6HS.THAT is the most recomended plug for the HT's.
I don't know who told you a champion CJ8, But Champions work better in cars, Not 2 strokes. 20 might be a little short, Try setting ht gap at 25-28. Norman has some VERY GOOD suggestions. Also, If you can ever get it to idle, check the intake for leaks. Just drizzle some water over both fittings, engine and carb, and if it dies, you have a leak.
fatdaddy.

 

[BigBlue]

Did you check the coil as fatdaddy suggested? What about disconnecting the kill switch from the circuit? Coil or switch may have corrosion since it did get rained on. Norm and fastdaddy are the 2 best at diagnosing problems.

If you haven't done an Ohms check on the coil your wasting your time. Your just playing "not it" with everyone trying to guess what's wrong.

A good mechanic will conduct checks on each part before moving onto the next possible problem. I know we all want simple solutions to our problems, but some time we have to take the advice that others give us to find the solution.

I am not trying to be a hardass with you or get on your case, but trying to help you find your solution to your problem.

Good Luck,

Chris
AKA: BigBlue

 

[BrandonG]

Rebuilt the carb, put in a new air filter (one in there was wet with oil/gas), checked that the jet was clear and put back in correctly, and tested the float valve which works fine. Oh and the choke was off for the most part. I occasionaly do 1/3 to 1/2 when tryin to crank it.

Couldnt even get a pop now, pedaled over a hundred yards but nothin.

Ill try and find a buddy with a meter so I can test the ohms and whatnot, but for now I cant do that.

Any other suggestions?

Yall are the best!

 

[Norman]

the coil on the magneto has 3 wires white, blue, and the ground. There is a 4th wire that you can't see real well it's the ground wire from the coil windings. It's a bare copper wire that is soldered to the laminated coil frame. Usually you can't see it until the magneto coil is taken off the engine, Sometime they are not soldered real well or have a so called cold soldered joint. That's one place to check. also all connections should be soldered even the crimped ones. then checked with a meter, be sure to wiggle the wire when checking cause a wire might look like it's soldered good when it ain't.

To do a good check on the cdi and magneto coil your going to need an ohm meter. If you don't have one volt/ohm meter they are not expensive $10.00 and up is usually the price for them. Harbor freight gives them away with a special coupon when you buy something over $9.99. If you don't have a inch pound torque wrench you can get one at harbor freight for around $15.00. use the 20% off coupon and the special coupon for the meter walk out with 2 useful tools. Hey they may not be high quality tools, but we all did buy a china engine didn't we?