Starts only with starter fluid

**hush** · 22nd December 2025, 23:04

So I have this "free" 2008 Hyosung SB50 Super Cab scooter I was given and so far the bill is $650 way more than the bike is worth really but I like saving old bikes so I keep throwing money at them. So far I have replaced carb with new one from Korea, ignition, reed valves, battery and tires plus stripped it to frame and repainted it. Here is the problem, it will only start with a squirt of ether (starter fluid) and then it runs quite well even idles. I have had the top end apart and removed piston to check rings and bore but both are ok, initially I thought the problem was lack of compression but that does not seem to be the case, I only guessed at that as I figured the lack of compression was preventing the vacuum tap from opening and supplying fuel. Does anyone have a thought on what my issue could be? I have removed the engine 3 times to bench it, cleaned out the carb 8 times just to ensure it wasn't something easy like the slow idle jet blocking.

**jellywrestler** · Yesterday, 00:20

Originally Posted by hush

So I have this "free" 2008 Hyosung SB50 Super Cab scooter I was given and so far the bill is $650 way more than the bike is worth really but I like saving old bikes so I keep throwing money at them. So far I have replaced carb with new one from Korea, ignition, reed valves, battery and tires plus stripped it to frame and repainted it. Here is the problem, it will only start with a squirt of ether (starter fluid) and then it runs quite well even idles. I have had the top end apart and removed piston to check rings and bore but both are ok, initially I thought the problem was lack of compression but that does not seem to be the case, I only guessed at that as I figured the lack of compression was preventing the vacuum tap from opening and supplying fuel. Does anyone have a thought on what my issue could be? I have removed the engine 3 times to bench it, cleaned out the carb 8 times just to ensure it wasn't something easy like the slow idle jet blocking.

whay not use the original carbie?

**F5 Dave** · Yesterday, 08:11

Is the choke cct actually working? No choke will be very hard to start. It's actually an enricher not a true choke, but semantics.

**hush** · Yesterday, 16:47

Originally Posted by jellywrestler

whay not use the original carbie?

It leaked due to float level valve being worn out and plastic mount is non adjustable, I bought new original carb and tried to swap parts but still leaked so area must have been worn out.

**hush** · Yesterday, 16:59

Originally Posted by F5 Dave

Is the choke cct actually working? No choke will be very hard to start. It's actually an enricher not a true choke, but semantics.

That occured to me too as I drifted off to sleep last night, the bike displayed same issue with both carbs so problem followed replacement. Today I tested the cable feed to the auto-choke but there is no power? From the wiring diagram it feeds from the white/red wire from Regulator but could not get power there either, replaced regulator with a spare and still no power to choke, I am wondering if I can run power directly to the auto-choke to see if that makes any difference?