# 50cc scooter



## paul8885 (Mar 18, 2005)

I have a 50cc Kymco scooter that is starting poorly and I don't know much about 2-cycle engines (bigger problem). However, I am a quick study.

- 2 screws on side of carburetor: one appears to increase idle speed somehow, the other appears to affect mixture at idle. In general, once it starts it dies pretty quickly until warmed up, then okay no problem at idle.

- The scooter accelerates poorly at load from idle. A rather hellish noise (rattle...shall we say) from the exhaust suggests the mixture is not to its liking. Once past this area, the bike runs nice and gets good mileage.

I know, not much to go on, but could someone speculate. This engine has 6000K on it and has been rebuilt twice. I drive it back/forth to work at 30 MPH for 5 miles...no biggy.


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## bugman (Aug 12, 2004)

sounds like youshould up the mixture screw maybe i quarter of a turn to maybe a half a turn out


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## scrench (Dec 8, 2004)

how much fuel has been ran through it ? has it been rode alot ?


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## bugman (Aug 12, 2004)

haha, read the last sentence scrench. but it sounds like it does need a adjustment. if the carb was rebuilt it may have not been set back right


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## scrench (Dec 8, 2004)

exaust might be stopped up


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## bugman (Aug 12, 2004)

yeah never thought of that. how long ago was it rebuilt?? if it was a long time ago it might be stopped up. plus for some reason bugs and spiders love engines. that may have clogged something


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## paul8885 (Mar 18, 2005)

Engine was rebuilt a second time about a year ago. I drive it to work daily about 10 miles round trip. It started this raspy sound on acceleration from idle about a couple months ago. Its been downhill ever since...just gets worse. Power at low end is way down. I have to climb a 7% grade for a mile to get home and it crawls, spits and pops about 20 mph up that hill. Fiddling with the mixture screws can get it to start and stay running a bit longer, but it still runs poorly after idle. Once no load is on it there is little problem cruising at 30-35 mph.


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## paul8885 (Mar 18, 2005)

Oh, that plugged exhaust deal is interesting. Dumb question probably: How do I check that?


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## bugman (Aug 12, 2004)

either a compression gauge or just take the muffler off and look at the exhaust port.


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## paul8885 (Mar 18, 2005)

Took the exhaust off and viewed the port...looked fine. Started it without the exhaust on: lots of noise and, obviously, this threw the mixture off a bit with no back pressure. It did run about the same, so, I put the exhaust back on.

Could this be primarily a carburetor problem? Could it be dirty? Could I run some kind of cleaner through it or is this taboo with two-cyles?


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## bugman (Aug 12, 2004)

well without the exhaust it was running like it had a stright pipe. yeah you could try a carb rebuild now. running carb cleaner through it will most of the time ruin the carb if its of some age. may be it just needs a diaprahm.


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## paul8885 (Mar 18, 2005)

Carb rebuild, eh? Do you know a good 2-cycle mechanic in the Carlsbad, CA area?


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## bugman (Aug 12, 2004)

no, you can do it yourself. get a kit, disassemble on the weekend and soak the carb in cleaner for a few hours then use the rebuild kit to rebuild it.


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## paul8885 (Mar 18, 2005)

Took carb apart and cleaned it...no big deal. Engine still runs the same. Symptoms: starts very hard when cold...have too play with throttle a lot. Runs smooth up to around half throttle with minimal load. Pops and garbles when bigger load applied and you try to accelerate through it (such as a hill).


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## bugman (Aug 12, 2004)

did you use a rebuild kit in it?? try messing with the high speed screw a bit by going up a little at a time with it.


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## paul8885 (Mar 18, 2005)

Dealer says no rebuild kit available for this model of carb. It really looked in nice shape when I took it apart. I've tweaked both the mixure and air screw in all kinds of ways. I can actually get it to start and run better initially a little richer, but it fails from idle (stalls) after it warms up. Under all various settings, it still acts same under load: no power at low RPM until I get it up to around 25 MPH. A load and low RPM is bad news right now.


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## bugman (Aug 12, 2004)

hmm, they can sell you parts to rebuild it right? well sometimes a carb may look nice but even the smallest peice of dirt sometimes may screw em up, diaprahms may have a tiny pinhole in em and they will run like crap and everything just won't do right


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## Smalblok355 (Oct 22, 2004)

what manufacturer is the engine?????I know that alot of these gas scooters have Zenoah engine's on them and Zenoah does stand by their products if something is bad with it.......if it is a Homelite you might be out of luck.lol......since Hoemlite is no longer being manufactured unless you get a refurbished on....lol


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