problem w/ muffler? carburator?

I took my moped out for a ride and things are OK ... until the engine started making funny pop-pop sounds and bits of blue smoke. Do I have a dry gas perhaps? Or is it something else?

I cleaned the carburator yesterday and so that's not the problem. But perhaps I have dry gas? I'll drain the tank and get new gas for it.

I don't think I'm running lean/rich, since I have the same mix as before. But the gas is from about 2 months ago ... even though I just added some (but also from 1+ month ago in a gas can). I put the carburator back together properly and everything was fine last night. The engine actually hummed at a high pitch and seemed to go very fast (no speedometer). I have no idle now, but that's a problem w/ the throttle grip and shoudl not be related to the muffler sounds.

Could I have a seal loose somewhere? The popping seems to come from the front of the muffler, not the back. But I was riding in the rain, and so my hearing may have tricked me. Maybe just water in the carburator?

But any other suggestions of things to look for would be greatly appreciated. I think she'll get me home this evening ...

Re: problem w/ muffler? carburator?

Rings ??

If you're getting lots of blue smoke, that would be my guess, but I'm new

at this.

Re: problem w/ muffler? carburator?

david f martin /

I've noticed with my bike that it tends to 4-cycle quite a bit more than usual when I'm riding in the rain. I figured the aircleaner element was getting wet, restricting the amount of air getting to the carb and causing it to run too rich. Just my theory...


Re: problem w/ muffler? carburator?

Ron Brown /

And an excellent theory it is too, but you should be able to solve it if you have a good air box and filter.


Re: problem w/ muffler? carburator?

Bad rings in a 2 stroke will not cause an extra amount of smoke of any color.

There is no oil in the crankcase beneath the piston to get past "bad rings".


"dry gas" is not 'bad gas'

Dry gas is a liquid you buy and put in your gas tank to absorb water that may have condensed in you gas tank or carburetor.

You know that "gas treatment" I speak of ?

It has "dry gas" (alcohol) in it ...along with other solvents to clean fuel systems.

Two month old gas should be fine...

Put a capful of gas treatment in if you havent already.

When you say you 'cleaned the carb'... did you use 100 psi of compressed air?

You really have to have the high pressure air to blow out stuff in the small orifices.

That ped guide will clear up 95 percent of most ped problems.

When is the last time you put a new spark plug in it?

Try a brand new one...

.. if that doesn't fix it ... put the old one back in and clean the carb and drag a clean piece of paper through the points.

Re: problem w/ muffler? carburator?

No smoke with bad rings.

Makes perfect sense when you explain it like that (Doh')

Re: problem w/ muffler? carburator?

Yeah, the rings are almost new (less than six months). So I don't think it's that. I cleaned the carb w/ just carb cleaner, not sure of the psi on the air. I will clean it again more thoroughly, though. But it seemed really clean when I took it apart last time.

I think the rain theory is good, I'm probably getting lots of water in my carb. How exactly could I fix that? Or just not ride in pouring rain, eh? I'll also make sure the carb is on tighter next time.

Also, my sparkplug is about 6 months old or so, a Bosch Platinum. So I think it should be fine. But I'll take it out and clean it off, since I rode in lots of snow this winter. I think I'll take and clean the cylinder a bit (at least the front of it).

I hope this problem isn't a major thing ...

Re: problem w/ muffler? carburator?

david f martin /

We use Bosch plugs at the VW shop I work at, and we only use the copper electrode type. I've been told that the platinum type has a much thinner electrode and they are more prone to fouling. I don't know how good that information is, but you might try a copper plug and see if it makes any difference.


special plugs

In the motorcycle world the special metallic plugs were offered because they were MORE resistant to fouling

By now I have forgotton the scientific reason why... but I did used to know...

I imagine the same is true today.

The downside is they usually cost twice as much.... but if they last twice as long???

My peds have never run overly rich (even when I got them)... so I have never had dark brown or blackish olugs.

So I have been able to get away with standard plugs.

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