pinky purple spark... no crank still

I know you are tierd of reading my cry's for hep.. im tierd of posting them.

I am totaly lost..

I have spark gas and compresion but im just not able to start.

I check spark and no mines not blue it is more of a pink to purple color.

Second I put gas in the spark plug hole.. that didn't work either (even though i get plenty of gas i tried it anyway.

I checked timing... as best I could.. with the piston just a lil i miean a lil before TDC I took off the magneato cover... the line the T both lined up with a V notch in the housing. I am guessing this means timing is all correct.

The next thing I am wondering if myabe it isn't sparking while in the block.

(only thingI can think of)

maybe the metal spark plug cap is grounding out or something next to the block.

So here is my question.. is this something that could happen?

I looked on my coil? and it seems like it is connected directly to the plug wire.. I tried to pull the wire off but it feels like all one peice.

I would guess a new wire wouldn't hurt anything so I guess I need to find one of those first.

1980 peugeot 102. iw as told by chris from the moped warehouse that the 102 is a rare bike and parts were limited becuase demand was so low.. only becuase the bike hardly ever tore up and was one of the most reliable peds ever built.

While im glad this is true... it makes it hard for me. :0)

Thanks agian guys.. as always any suggestions would be apreciated.

Ps... I kicked the tires and re painted it... (niether of which helped it to start lol)

Re: pinky purple spark... no crank still

Try this:

Take off the exhaust, then try to start your ped. With the exhaust off, you will be able to hear if the plug is firing in the block (it will be a loud POP).

While you've got the exhaust off, check your exhaust port to make sure its not clogged with carbon. Lay the ped on its side and look in, you should be able to see the piston moving inside. If there is a bunch of black crap blocking your view then scrape it out with a screwdriver, being careful not to damage the piston or cylinder. (all of this is covered in Freds guide)

Re: pinky purple spark... no crank still

"pinky purple spark" sounds like a weak coil or magnet to me.

Richard

Spark plug ?

How old is the spark plug ?

When is the last time you bought a new one ?

Pinkish purple isn't that great... and will often happen with a spark plug has been gas fouled.

And you are somewhat correct... a spark plug that has been gas fouled will quite often spark outside the head... and then not fire IN the head.

Buy a new plug.. then test it outside for spark color before you install and try to start it.

Re: Spark plug cap arcing

and as far as the plug cap arcing... you can wrap it in a few layers of black electrical tape... that will stop any "spark leakage" temporarily to get it to run as a test... the tape will heat up and melt away after a short time if it runs and gets hot though.

Re: Spark plug cap arcing

the plug is brand new i have tried several diffren't kinds.. some start off burning bloue then the next time without anything turns pink.. then blue.. it isn't ever consistant.

points ?

Allright... and you have pulled 400 grit wet and dry sandpaper through the points and then sprayed them with cleaner and/or compressed air?

And pulled a clean piece of paper through them ? and it came out clean ?

and then checked all connections on the wire going from the points to the coil ?

(you can run a wire straight from the points to the coil to bypass the wiring harness)

why?

gimmyjimmy /

why would a plug fire outside the head and not in?

carbon on the porcelin?

Re: why?

Is the plug grounded to the motor when it sparks??try cranking it at night in the dark and see if the coil is arcing sparks out to the lead wires ...

Re: why?

gimmyjimmy /

Rog,

duck is having the spark problem, I was curious why a plug would fire differently inside and out.

Re: pinky purple spark... no crank still

Ron Brown /

Duck,

I posted this under your "still confused" thread on 12/2. What happened? This thread looks like you never read it:

Duck,

Next time you start a new thread, mention the moped make and model again. You know this, but those of us who are not busting knuckles on it tend to forget. Otherwise, this was a good explaination of the problem.

I think you are close to running, you are just getting lost in the big picture. Try to focus on one problem at a time and resolve it, or, if you can't, remember it before going on to the next.

Another thing to keep in mind is that 2 strokes are so simple, there is nothing to fix when they don't run. This makes repair very difficult. Anyone who owns a 2 stroke who tells you they have never had a "@#$% thing won't start problem", only to have it fix its self, is usually lying.

You are not alone, we feel your pain. : )

First, you need to figure out why releasing the decomp lever makes it easier to pedal. An earlier post sugested that it may be trying to run. I tend to agree with this except that with as much fuel as you have floating around you should be blowing mass quantities of smoke when it fires.

The decomp valve is a simple device, when you pull the lever, a small mushroom valve in the head opens to allow engine compression to escape. You should be able to hear this when you operate the valve, you may also see fuel escaping from the head in the area of the valve. When you release the decomp lever, a spring closes the valve and the noise should stop. You may have to let someone else pedal while you listen for this.

In operation, you operate the decomp lever to make the engine easier to turn over so that the centrifugal clutch can engage fully to turn the engine. As the engine begins to turn, the clutch is dragging which wastes some of your pedal power. When the engine turns fast enough to fully engage the clutch, this drag disappears and you are turning an engine with no compression which feels like a "mushy" load. When you release the decomp lever and get engine compression, you should feel the compression pulses but this is a 50cc engine and will not be hard to pedal, however, it might sound and feel "better". You may be mistaking this for "easier to pedal". Make sure the decomp valve is working and then don't worry about it, other than to get the engine turning.

Spark plug. This is the bane of all 2 cycles. Spark plugs can appear to work fine in open air, and never fire in the cylinder. The problem is that air is not as good an insulator as a compressed fuel/air mixture. Often, when the plug tries to fire in the cylinder, the additional resistance of the mixture and the plug being wetted will combine to cause the spark to leak across the surface of the insulator around the center electrode.

Buy another new plug or two. They do not need to be platinum, even if they are not the exact number, if the threaded portion is the same diameter and length, they are fine for testing. Just set the gap to your ped's spec. Each time you have tried to start your ped, take the plug out, if it is not bone dry, wash it with carb or brake clean and blow dry it with compressed air or shake it and set it aside to dry. Replace it with one of your clean, dry plug. Just for laughs, take any spark plug and gap it at about .030", laying on the head, this should produce a good fat spark. and tell you your spark is good.

You obviously know where the points are. Turn the engine slowly until the points just break contact. Using a pencil through the spark plug hole, make sure the piston is near the top of it's stroke (closest to the plug). If you are ambitious, 1 to 2 mm before top dead center is where the points should break. This does not have to be perfect to run, if it feel like you are near the top of the stroke, this is ok.

Trying to start the ped.

Turn off the gas and drain the carb if it is easy to do, it will save pedalling time. Now, using the decomp to get the engine turning, pedal like hell for way too long. Change the spark plug for a dry one and repeat. When the plug comes out dry, you have pedaled enough.

It is possible that while doing the above, the ped will spontaneaously start. You should be so lucky!

The purpose of the above exersize is to clean all the excess fuel out of the engine. Once a 2 cycle is flooded, you have two problems, the plug gets wet and leaks, and your mixture is not easy to lean out again. The above exersize solves this.

Now, check for spark using the "plug on the head" trick and install a clean, dry plug.

Turn on the gas, set the choke and pull the decomp. Pedal. As soon as the engine turns ok, drop the decomp, keep pedalling and slowly roll on throttle. Any more than 1/4 throttle is too much.

If the ped does not start, immediately turn off the gas, because we do not know if the carb is flooding yet.

Begin again at "Trying to start the ped.", but this time, do not use the choke and make sure that the last plug you use is not the same one.

One of the above methods should at least make some smoke and noise. Post the results.

Ron

Wiring:

It does sound like you could have some wiring problems. Do you have matching colors from the magneto into the ped wiring harness?

It would be unusual for the ignition to be wired wrong as this wire goes through the points to the ignition coil.

Someone mentioned burning out the headlamp because the tail lamp is not burning. This would make sense to me if the engine was running but I am amazed that you can do it by just pedalling. You say 12volt bulb. Any idea of the watts or amps? You should be using about a 25watt headlamp and 6 watt tail lamp.

Ron

Re: why?

Ron Brown /

Jimmy,

Look at my post at 09:57 in this thread, the explaination is in there somewhere.

Ron

timing

Did you check the timing of your piston?

if the spark fires at the wrong time ie. if the piston is in the wrong position.

I had a motobecane that was having the same porblem, untill I ajusted the timing.

Its easy to do, you can buy a timing tool to be real precise, or use a stick with some marks on it. put the stick in the spark plug port and crank the pedels slowly until the piston is at its highest point. once it is there check to make sure your points are lined up correctly.

good luck

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account