Hyosung 50cc Scooter- Won't Start Cold- Need Help

[tmcklveen]

Hi everyone,

I'm new to the scooter world, as I've just purchased my first 50cc Sense. I've been all over forums for the past two weeks, and cant figure out what is going on with the scooter.

The scooter will not start on it's own if it's cold. I can get it to start with starter fluid. Once it warms up (about 2 minutes), it runs amazing. My first thought was the auto bystarter was stuck open. I pulled it off, and tested it. After about 2-3 minutes, the pin extended about a quarter inch. I think it's operating correctly.

I then sprayed some carb cleaner into it while it was running, hoping that would clear out anything that may have been causing the issue. No luck. I've also reset the the two screws on the carb to the standard settings (according to a forum- 1.5 turns back from all the way in)

I've derestricted it by cutting that blue wire, and once I get her warm, she goes about 40-45mph (according to the speedo). I really want to avoid taking it into a shop, as I bought this thing as a value ($150).

Any thoughts?

[OverReved]

How are you trying to start it when it is cold? Are you using the starter or kick starting? Have you tried both methods yet, doing so and getting better results could indicate a small problem.
The enrichment circuit seems to be operating as far as your enrichener is concerned. You still can't tell for certain it's actually working till you check for voltage at the pins on the harness going to the enrichener and do a physical inspection of the ports in the carb for that circuit.
I'm not sure what two screws you've reset ( I can guess but I'm not going to assume) 1.5 turns as it relates to an air/fuel screw is a base but some of them need up to three turns, any more and you'd need a jetting change.

You may want to remove the spark plug and inspect its tip and give more information on the bike in general. A just bought scooter for 150$ could have 50 miles and be a fantastic steal or 25,000 and be on it's last leg for all one could guess.

[mainepeace]

1/4 inch is generally not enough for the auto-enricher, though it might be enough for that carb. However, even with it extending, that doesn't mean that it's not getting stuck. What you describe though with the motor running fine after 2 minutes implies that *something* is changing after 2 minutes. If its not extending then the motor *needs* the extra fuel, so it would imply that the enricher is stuck CLOSED, which is not the case from what you say.

Your A/F mix is way off. When the motor is warm its less of an issue which is why it seems to run great. I bet still need to tweak it a bit. The Hyoseng use a different engine and a custom made carb so the 1 1/2 turn starting point may be right. However, it's just a starting point and needs to be tweaked. Triple check that the idle passageways are clogged. Going from what was said before, it seems like its NOT getting the extra fuel it needs when cold. That means a clogged passageway in the enricher circuit.

Do you have a 2 stroke or 4 stroke? If its a 4 stroke version, adjust the valves.

Greg

[urhb65]

I just picked up a 2000 Sense 50cc scooter for my daughter to get around town and back and forth from work. Have the same problem, try to start it when it's cold and no go, but if I "choke" it by putting my fingers over the breather holes where the filter is, she'll start right up, leave them there for a few seconds (about 10) and then let it go she'll run and the at some point really start to rev up on it's own. I think I'm going to have to pull the carb off and go through and clean it. Thanks for the heads up on what to check. I'll look around the forum to find a post that goes over cleaning the carbs.

[tmcklveen]

I took the carb off tonight and noticed a SMALL metal cylinder that was located in the same channel as the Auto-Bystarter/electric choke. This little guy was cracked in two pieces. The inside diameter was the same size as the choke needle. Half of it fell right out when I pulled the carb apart. Everything looked clean, so I assume this is the problem? I haven't seen many carbs in pieces before, so if that is not normal, let me know. The rubber gasket was dried out and broke apart as well.

Anyone know a good place to pick up a cheap carb that will work for the 50cc Sense? (assuming the above description sounds like there is no hope)

Of course, if you search for "hyosung sense" you get little to no results. Any input would be very helpful.

Thanks.

[4getful2]

e-bay

[tmcklveen]

This may help... Attached is a picture of me holding the broken piece inside the carb.

[mainepeace]

That's the tube to suck the fuel up into the idle bypass circuit. If its broken the carb can't get fuel. Hard to find that part, most likely you'll have to replace the carb.

Greg