moped chugs after 15min of driving

Hey gang,

I have 2 mopeds and they both have the same problem. After a long drive full out, 15 to 20min. They starts to chug allot and drive at half the speed. If I let the ped sit for 10 min it drives fine, but after another 20min of driving it starts up again. I was using supreme gas and synthetic oil. Since then I changed to reg gas and reg 2stroke oil. The peugeot did the same choking thing after 15min, but cleared itself and didnt lose half its speed. I find the spark plugs were black and dry when i used the synthetic oil and super gas. I havent done a plug chop on this new "regular" mixture im using.

Any tips,


p.s. the other moped is a motobecane 50v 1970, if that makes any difference. It takes longer to act up...the chugging...the motobecane also backfires when the chugging goes on

Re: moped chugs after 15min of driving

Dry, black plug chops show you might be running a little rich but unless the plug is fouling i don't see a connection between the plug and your problem.

Basically, higher octane fuel does nothing but help prevent pre-ignition and is most useful in high compression engines.

The fact that _two bikes_ have the same trouble is probably more than coincidence. What makes you suspect the fuel and/or the oil type? At first glance this would seem to be more of a fuel delivery problem.

Re: moped chugs after 15min of driving

MBKs are notorious for weak condensors. Ron Brown had similar symptoms and it was a bad condensor. Then also you want to check that the gas cap is venting. don-ohio

Re: moped chugs after 15min of driving

Hey Don, do you sell condensor's or something.....just kidding....but I do notice that your responce to most people is "get a new condensor".

It turns out that you were right about the venting problem, both bikes gas caps vents were plugged. The Peugeot was more plugged then the Motobecane...go figgure, that the Motobecane took a longer time to run poorly.

Funny that one goes and looks in all the obscure places when a moped is running improperly when the answer is right under your nose.

Anyways, thanks for all the've all made mopeding a greater experience then it already is.....sha la la laaaaa.


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