still confused.

Okay... welp let me start off by saying I am very very confused right now.

over the last week or so I have been trying my hardest to get my moped to run.

I have awesome compresion. I have bright blue spark .. from a bosch w8ac gapped at .016

There is gas.. alot of premixed gas. :0)

I amnot sure exactly how this decompresio0n thing works.. in theroy I do .. but listen to this does this sound normal.?

When I try to start my ped I just sit or stand on my ped while it is on the kick stand and pedel it like I was riding a bike.

I have to press the decomp lever in to start off.. I generaly hold it a few second until I get up some speed but when I let off the lever.. I thoguht it might was supposed to get harder to pedel.. instead it actualy seems to get a bit easier and speeds up.

Also I noticed that if i take the plug out there is a little bit of gas on the tip... I can then ground the plug and get spark.

Are you supposed to give the moped gas when you try and start?

i pedel my arse off and wiht the choke in I can turn the throtal and it makes a load Rummmm.. rummmmm as I turn the throatl back and forth but it isn't actualy running per say.

I for the heck of it took off the exsuast tube today and found that there was quiet a lot of gas there.... Im talking I unscrewed the exsuast and probly like 1/8 of a cup ran out.

I know with spark gas and compresion it should run but hel mines not... a few weeks gone by and I just am at a stopping point .. I want to ride it is so nice outside. any suggestions would be nice. Im even thinking about breaking down driving 350 miles plus to panama city and letting a moped shop look at it.

Re: still confused.

Are you sure you are operating a decompression lever? On my Puch moped the lever used to start the motor is not a decompression lever but a clutch that engages the motor to the pedal mechanism. Unlike a traditional clutch, it engages when the lever is pulled in and releases when the lever is released. In other words, to start the motor, you need to keep holding in the lever. It sounds like this is what you have since it gets easier to pedal when you release the lever.

Re: still confused.

the cable runs down to the engine block.

Re: still confused.

XBrandon EdgeX /

if it suddenly gets easier when you release the decompression lever, then it's probably running a little bit and then dying. When you start it, the choke should be on and then pedal it over a few times without touching the gas, and then as you're pedalling, gradually give it gas, GRADUALLY. At least do it gradually the first few times you start it until you find the spot that it will start at. Most bikes have a catch on the choke that un-chokes it once you give it enough throttle.

Re: still confused.

sounds like your float (in the carberator) might be stuck open if gas is just running out, could be the float is sunk or just a piece of dirt in the seat

Re: still confused.

Had the same problem on a older Tomos, plug out and peddle by hand watching it, good spark. What I didn`t know is when peddling tring to start it I lost fire (spark). TO Fix, I filed the points and cleaned them good. Sound familiar? Doug D.

Re: still confused.

ive sanded and cleaned the points.. doens't make sinc eto me that it would fire out of the block but not in it.. makes since though.. im thinking and have been thinking the same thing.. shoot even if it was getting a little to much and even too rich gas if the spark was really good then it should still crank.. although i think it would be running terrible it should atleast run... right? wrong.. heck... I dunno anymore. ps. I sprayed some cheap brand of start fuel in it and tried to start.. nothing.. is there a way (bare with me guys) to check spark while the blug is in the engine?

Re: still confused.

XBrandon EdgeX /

hey, is the spark plug cap made of metal? I had a puch with a metal plug cap and something inside it shorted out so that the spark would not make it to the electrodes on the sparkplug, but instead arced between the spark plug cap and the outside of the cylinder head. If your spark plug cap is metal, I'd replace it with a rubber one. If it already has a rubber one, then that's not the problem.

Re: still confused.

Are you also holding in on the choke lever on the right handle and twisting the throttle when your hear it trying to start.

Decompression is on the left handle and to check it you should follow the cable down where it terminates next to the spark plug.

Also check the connections on your kill switch (Stop/Run).

check your tail light bulb and make sure the tail light bulb and brake light bulb are not burned out.

Could be a blown head gasket

Could be improperly timed so it is not firing at TDC.

Re: still confused.

I didn't read any of the followups but you might try ether since you seem to be having trouble starting. If you don't make a regular habit of it, it shouldn't hurt. Just shoot some inside the carb. this should make it start even if the choke isn' t working.


Re: still confused.

Ron Brown /


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.


Re: still confused.

Ron last night for some reason My headlight would not come on either.

nothing in the electrics has been worked on.

I will also ask a question and I hope to hell the answer is no.

a few days ago at school I got a new seat and had it welded to the seat post becuase the bars where diffren't. Could this have screwed all my electric stuff up?

I will know tommorrow whatrs up with the head light.. ps The tail lights and brake lights work fine and now the horn actualy makes a noise... :0)

Re: still confused.

Ron Brown /


Welding should not screw anything up.


Re: still confused.

Hey, I normaly up plug everything myself, But if you leave something on, run switch, light, ect.The arch can run thru it, melt points, blow a bulb, ect. I am speaking of a non-battery bike like a Tomos, if battery powered simply unhook it. This is not every time Im talking about, just once and awhile.Remember the electricity will go to closest ground. Doug D

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