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Post by Deleted on Dec 10, 2016 14:01:09 GMT -5
Ok, I am new to scooters and I am no mechanic by any means. So on that note. I bought a scooter for my daughter so she could get around. I found a '07 Hyosung SD50 Sense 49cc 2 stroke scooter. Needless to say it was not running and took the kids word that it was minor problems. When I got it home I started turning it over with the kick start before charging the battery. It sounded like it wanted to turn over.. After about 5 min. of looking at the motor, realized spark plug is not in, so I screwed it in and voila Starts right up. Ran good too for a little while then parked it... The next day I go to start it up and turns over no problem revs a little high while it warms up then comes down to a nice idle. I took it for a spin around my apartment complex and noticed it was not giving any power at full throttle its starting to bog out and almost stalling I had to lightly throttle it gas/release, gas/release to get it back. after that it just slowly kept shutting off. It would start up nice kick over fine but shortly after it would stall. If i started it and gave it a little gas on and off it would stay on but when i would stop gassing it it would shut off... or if I full throttled it the tire didnt spin at full speed and i again would bog out and stall. I have replaced the carb. brand new, I checked the vacuum line there is suction, and gas is being passed to the carb. I believe it is due to flooding but again i am no mechanic... spark plugs are brand new, i adjusted the air/gas mix i shut the valve then gave it 2 and 1/4 turns and it idles great... I noticed after it stalls out if I let it sit for about an hour or 2 I can kick it over and it will stay on at a nice perfect idle for a long time, but as soon as i start throttling it eventually it starts to stall if i dont keep twisting and releasing the throttle...
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Post by pinkscoot on Dec 10, 2016 14:28:50 GMT -5
 I have a Hyosung Primo SF50 scooter, they are great scoots but have a Morini engine so there aren't many after market parts. It sounds like several things could be possible. Did you drain the gas tank and clean it out? It could have dirty gas in it. What kind of shape is the fuel filter in? Its attached to the petcock in the tank I believe. When you suck on the vacuum line does it open the fuel petcock and send gas to the carb? Its possible that the petcock isn't letting enough gas flow at more than idle. Have you checked the float valve to be sure its level when you hols the carb upside down? Did you do anything besides just run the A/F adjustment out to 2 1/4 turns? There is more to it then just turning it out. Read here on how to adjust it. If it is a new carb where did you get it and did you clean it? Even new carbs need cleaning. What jets are in the new carb compared to the old and is the needle setting the same? These are all things to look at. It sounds like the CDI is good mine was bad and I had to get an OEM CDI. The high idle when you start it is the enricher and they close off. Check these and get back to us. Maybe one of the smarter guys will have an answer.
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Post by Deleted on Dec 10, 2016 15:05:11 GMT -5
i have not checked the gas.. it was sitting for a while and i just put gas in it.. it has a separate tank for the 2 stroke oil mix and mixes on its own.. i have not checked fuel filter either. Honestly this is why I came here because I know zip about these things however I do learn fast..!!! when the scooter was running i removed the vacuum hose and the scooter revved up slightly and the slowly started to stall out, then i removed the hose next to it which was the fuel line and needless to say gas splashed all over(SMH) and scooter started to sputter. but it starts right up 97% of the time no problem...!!! I will look into draining the fuel and checking fuel filter maybe even drain old 2 stroke oil mix flush lines put new gas and new oil mix clean fuel filter... if that dont work i will remove carb and inspect it.. I will need further instruction on how to inspect a carb. the carb. that i got was off of ebay and it was a Hyosung SD50 CARBURETOR ASSEMBLY  |
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Post by pinkscoot on Dec 10, 2016 16:46:21 GMT -5
Yes that looks like the Hyosung carb. Here is everything you need to know about that carb, HERE. While you are in there compare the jet numbers to the carb that came with it. Also check the needle height. Be careful with the carb O-ring on the flange, its a trouble spot for air leaks that will bring a whole new set of headaches. |
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Post by gsx600racer on Dec 10, 2016 17:30:48 GMT -5
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Post by Deleted on Dec 10, 2016 19:40:46 GMT -5
the next time i look at it im going to clean the gas tank and the filter. make sure im running premium gas with a good oil mix... if that does not help me i will pull the carb off and examine what i can with the information i can gather from here and you guys. and yes gsx600 that is in fact the scooter that i bought.. the kid did not know what was wrong because he said it no longer runs... but we put the spark plug in an fired right up. the old carb was stalling out the exact same way it is now, with the new carb. So i am thinking its not the carb its somewhere else... i am no mechanic but the process of elimination has to lead me somewhere... what i will do also is take some photos of my carb set up and some video of how its running... thanks in advance for everyones help... p.s. gsx600 no way in hec was i paying 400 i got it for 260.00 and it runs, not well at the moment but it runs lol
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Post by pinkscoot on Dec 10, 2016 20:53:40 GMT -5
It sounds like a fuel delivery problem. Cleaning the tank and fresh gas might be all it takes. You shouldn't have to mix just fill the oil tank and use the injector. They have the oil input on the intake so it keeps it out of the carb. I found you the service manual for it and they are always helpful the link is here, Manual. Heeters is a good source for off the wall Hyosung parts. I think they were a dealer and have some inventory they are getting rid of. Keep us posted on your progress. |
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Post by gsx600racer on Dec 11, 2016 0:02:36 GMT -5
the next time i look at it im going to clean the gas tank and the filter. make sure im running premium gas with a good oil mix... if that does not help me i will pull the carb off and examine what i can with the information i can gather from here and you guys. and yes gsx600 that is in fact the scooter that i bought.. the kid did not know what was wrong because he said it no longer runs... but we put the spark plug in an fired right up. the old carb was stalling out the exact same way it is now, with the new carb. So i am thinking its not the carb its somewhere else... i am no mechanic but the process of elimination has to lead me somewhere... what i will do also is take some photos of my carb set up and some video of how its running... thanks in advance for everyones help... p.s. gsx600 no way in hec was i paying 400 i got it for 260.00 and it runs, not well at the moment but it runs lol Damn, I am good. LOL Iv seen that scooter on CL for awhile. I thought $400 was on the pricey side. Its cool that you got it for a lot less and it runs. I just finished my first Morini engine based scooter build. I am sure once you get the problems sorted out you like it. A actually like the front ends on them, they sorta look like a Honda Dio at first glance. I am waiting till spring to start tuning mine and breaking in a engine rebuild. There are several Morini guru's here that will get you up running in no time. |
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Post by benjiescoots on May 13, 2019 2:04:37 GMT -5
I know this is a long shot, but could you give an update on the solution you found? I am having the same issues with my 2001 Hyosung sense. Thinking CDI but could be fuel, really not sure.
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Post by harleyracer59 on May 13, 2019 2:54:56 GMT -5
is there an air filter on it? is there a filter in the filter housing? sounds like it might not have one. that would make it go lean on throttle. if its not the absent filter or a vacuum leak somewhere then its gotta be fuel. its most likely one of these 3 issues. take your time. if something is found wrong repair then start scooter. see how it runs before doing something else. that way you know how what you did affects the scooter.
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