Got Spark but not Starting

Lachiepower0402 · May 7, 2014

About 2 months ago I ran my bike which is china girl 48cc and idled it and then revved it a bit and then it died while revving. Then I attempted to start it about 20 times after that. Then I found it was my Magneto because I wasn't getting a spark. So I replaced my Magneto to a screaming roo magneto and also upgraded my spark plug to a NGK B6HS. So now I am getting a spark but it is still not starting. I have tried changing the choke setting all the way from full to open and in-between. Does anyone have any suggestions?

Thank you in advance

xseler · May 7, 2014

Being an old guy, sometimes the memory isn't the best......... Last time mine ran for a while and died, I'd forgotten to turn the fuel switch back to the "On" position.

Really.

Lachiepower0402 · May 7, 2014

LOL, Thanks for the suggestion but that wasn't it.

Regards,
Lachiepower0402

crassius · May 7, 2014

had a guy this week came in with about same problem - turns out his motor was full of fuel from forgetting to turn off the petcock

have seen so many CDI units spark well, but at wrong time that I built a tester to check both timing & spark - without a tester, you'd have to try changing the CDI

you might also look for oil around head gasket & seals

Lachiepower0402 · May 7, 2014

I have checked around the seals of the cylinder and its dry as a bone. Also is it possible to buy a tester like what you made or is it custom. Last of all, would I be able to check spark by dipping the spark plug in fuel, reinstalling and seeing if it coughs when I try and start it?

KCvale · May 7, 2014

Simple test.
Turn the fuel off, pull out your plug, without giving it any throttle pedal it up the street and back with the clutch out.
This will blow out any excess accumulate fuel in the crank case.

Put plug back in and try it.

As mentioned above having spark doesn't mean you are getting it at the right time.
If you replaced the mag coil it is quite possible you didn't install it properly which would screw up the timing.

You can reference this for more.
http://kcsbikes.com/topic.asp?TOPIC_ID=623

magrider · May 7, 2014

I've shot WD-40 into the cylinder before to get 2 strokes started. take the plug out, spray some wd-40 into the cylinder, probably 1 second worth, replace plug, and try to start.

wd-40 lubricates the cylinder also so it's not bone dry, unlike started fluid.

2door · May 7, 2014

We're assuming you've checked to see if fuel is flowing from the tank to the carburetor. You said the petcock is open but that doesn't confirm fuel flow.

Also I'll ask if, when you replaced the magneto did you by any chance remove the rotor (magnet) from the crankshaft? It will go on two ways. One way is right, the other way is wrong and the engine won't run.

Tom

Lachiepower0402 · May 7, 2014

I know that their is fuel flow because I can drain the fuel from the bowl. When I replaced the magneto I did not remove the magnet but I have observed that when my bike is upside down and I am testing for spark and the magneto cover is open the crankshaft with the magnet seems to be moving a small amount back and forth.

crassius · May 7, 2014

my tester is made from 1/2 a case, 1/2 a crank & a spark plug & mag, turned by a drill with timing marks painted on it - easy to make if you have an old dead motor around

if you can pry the end of your crank with a screwdriver and get it to move up & down, then your main bearing is bad and the seals will leak as it moves

Lachiepower0402 · May 7, 2014

So your saying if I take the nut that is on top of the magnet off and then try move the crank around with a screwdriver?

EDIT: Regarding the placement of the magneto on the crank, how exactly is it placed, in which direction, at the moment I have the coil on the left and the magnet on the right and the black marker label on the back of the coil.

crassius · May 8, 2014

you don't need to take the nut off, there is room to gently pry up on either end of the crank to see if the bearing is loose - something I always check before starting to work on an engine (altho it's not as big a problem now as it used to be before the newer balanced cranks)

Lachiepower0402 · May 8, 2014

Thanks for advice I will try that tonight. I also emailed Screaming too about my problem and they told me that the ngk b6hs is too hot. Is this true and does it affect anything related to my problem?

Thank you in advance

2door · May 8, 2014

The B6-HS is NOT too hot. It is used by most experienced builders here and has proven to be one of the best choices for a spark plug for the Chinese 2 stroke engine. There are others you can use but they aren't any better. The NGK is usually available at many auto parts stores so there is no need to special order it.

The folks who told you it is too hot are probably hoping you'll buy whatever they are selling instead of giving you good advice.

While you're at it, replace the spark plug boot too. The kit boot is junk.

Tom

TakeiT · May 8, 2014

I had the same issue and spent about 4 hours scratching my head.

-Remove the clutch cover (it's on the right side of the motor, with 6 bolts holding it on)

- Take off like normal. Does the clutch gear constantly turn when you let off the clutch, or does it appear to slip?

Lachiepower0402 · May 9, 2014

I have checked the drive shaft and can't seem to move it with a screwdriver by prying at it. I am unable to check the clutch yet because I can't find my drill phillips head bit because the screw it too tight to undo with a screwdriver.

I have noticed another thing which is that their is a larger gap between the magnet and the bottom of the magneto compared to the gap between the magnet and the top of the magneto, what should I do about this?

GearNut · May 9, 2014

For removing the side cover screws, use a hand held impact driver instead of a drill, like this one. A drill will only strip out the screw heads faster than doing it manually.

The air gap difference top to bottom is not a problem. The mag will still work as it should.

2door · May 9, 2014

Not sure what you mean by "drive shaft" and prying on it.

If you're still concerned about rotor to coil air gap, loosen the four screws that hold the coil to the case and insert a business card between the magnet and the coil. That will usually give you an equal gap, both sides.
As was said, the gap isn't critical but make sure the rotor (magnet) doesn't touch the coil.

Tom

Lachiepower0402 · May 10, 2014

I just read another forum with someone who had the same problem as me and their problem was timing as mine might be. Their solution to the problem was reversing the wires, so black to blue and blue to black and then they used starting fluid to help it get started, which I would use WD-40 like someone suggested in this thread. Would this be safe to try?

crassius · May 10, 2014

I've had CDIs with timing problems that could be fixed by reversing the wires and sometimes flipping the rotor over backwards - in all those cases, the CDI failed after a couple weeks. I believe it was because the timing was off due to an internal component in the CDI on its way to going bad in the first place.

Now, if a CDI is out of time, I just toss it.

Got Spark but not Starting

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