Sparta needs only minor help!!!

Michael Nesson /

I just picked up a great moped yesterday. It is a 1979 Sparta with a Sacs engine. The ped has no rust, lots of chrome with no pits, two passenger seat/pegs and great tires. Everything works except the horn! It ran great for about 3-4 miles backfired and died. My moped pal riding behind me said the smoke was pouring out of the exhaust. I cleaned the gas tankand replaced the fuel line. It started right up on the first try and had great power( 34mph). Any idea on what would make this smoke so much...I used a 50:1 oil gas mix. Ideas on why it might die after a 3-4 mile ride? Looking forward to your ideas!!!!! Thanks

Re: Sparta needs only minor help!!!

I would try 40:1 mixture,thats what I use on my puch

Re: Sparta needs only minor help!!!

Jason Luther /

if the previous owner had it running really rich then there is probably built up oil and gunk in the exhaust. use a good quality two stroke oil at 50:1 and it should clear up once its burned off. take the carb off and clean it well. make sure fuel flows out of the petcock as well.-jason

Re: Sparta needs only minor help!!!

Jake Van Order /

I'll agree with that. I recently picked up a Balboa that was smoking like a chimney. I switched it out for Gianelli and the smoke is gone. I figured it was that because I use Motul 600 which is pretty smokeless.

Try cleaning your exhaust. I like to use MAP gas, burn it out and then tap out the carbon. On most Sachs exhaust, you can take off the rear cone and tap out the baffle.

Good luck

--jake

Re: Sparta needs only minor help!!!

Michael Nesson /

Thanks for the suggestions! What would make the ped die after a backfire and then not want to start again...then with gas and clutch start up after ten minutes? I'll try a leaner mixture, check the plug and clean the exhaust.

Re: Sparta needs only minor help!!!

Xxxxxxx Xxxxxxx /

you may have screwed up a ring on your piston

dead ped + smoke + backfire

another thing i was thinking was maybe your carb is running to rich,and because there was too much fuel in the chamber it detonated, hmm

jon in noviy lef is always popping backfires but he does it on purpose by killing his ped while riding, jamming the throttle down and flipping it back on causing a detonation

Re: Sparta needs only minor help!!!

Xxxxxxx Xxxxxxx /

dude the reason that balboa was smokin was because you were running it on starter fluid ;) lol

jay

Re: Sparta needs only minor help!!!

sounds like a combination of things..

The heavy exhaust smoke suggests a lot of carbon build up. This could mean the combustion chamber has carbon. A piece of carbon gets red hot and ignites the fuel at the wrong time... backfire.

Carbon build-up in the combustion chamber reduces the compression ratio. This can cause overheating. You might be seizing the piston or there's just a lot of friction.. so the engine must cool a little before it will restart.

Timing should be checked. clean and gap the points (if it has points) and definately use a new, properly gapped plug..

btw, i wouldn't guess about using a leaner mix just yet.. not leaner as far as fuel / air and not 'leaner' about oil mixture until overheating was eliminated as a possibility. Going leaner with fuel or oil means less lubrication and/or a hotter burn.

Whenever you get a new bike the whole thing should be examined.. and pulling off the head is about the first thing i'd do. Just a few bad miles can send a sick engine to the morgue.

Re: Sparta needs only minor help!!!

Michael Nesson /

When I clean the exhaust on this ped....does the muffler need to come off and then take the baffle out of the chamber?

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