50 cc Scooter dies whilst idling?

[Raswan]

Hey guys,

Fiancee's got a 2009 Lifan LF50QT-15 scooter with 1500km on it that is on the fritz. Frankly, it's given us enough trouble over the course of its lifetime that I'm ready to sell it, but need to fix this one issue first.

Here's the problem: start it up, give it a little juice, and it will idle correctly for about a minute. Then, as soon as it revs down to normal idling rpm, it will die. Keep giving it a little juice, though, no problem. You can drive it around town fine, but if you stop for a light or stop sign, you've got to keep feeding it a little throttle, otherwise it will die. Doesn't matter if you run it for 5 minutes or half an hour, same problem.

I've adjusted the idle up a little, to the point where the rear wheel brake that keeps the back wheel from spinning during idle is overwhelmed and starts spinning. Fuel filter isn't clogged, and it drains fuel fine. Shot some carb cleaner in too, put seafoam in the tank with fresh gas, same problem. Friend who's knowledgeable about motorcycles suggested the autochoke, given it's behavior.

What do you guys think? I'm a relative noob here, but I can follow directions if they are clear enough and don't require super-exotic tools. I'm willing to spend a little to fix this so I can get rid of it, but I'm sicking of it sitting outside the apartment unusable.

I'm looking around too, but any suggestions for a place to get parts would be most welcome.

Thanks in advance!

 

[soccerballtux]

doesn't the ground keep the back wheel from spinning during idling? IE at stop light, the transmission or whatever should be disengaged...I think scooters only have one gear...hm I don't know.
So does adjusting the idle help? Can you describe what happens to the RPM when you adjust the idle up?
I would check the carb/throttle body-- perhaps it's closing and not enough air is getting in at idle. If there is a secondary throttle valve, make sure it is in spec and also not restricting airflow. My Suzuki bike is notorious for coming from the factory out of spec, no QA. Workers just installed parts and didn't bother tweaking to proper performance.

 

[Raswan]

On most scooters, yes the ground does that. But the lifans apparently have an extra feature that engages some sort of break so that, I don't know, if you've got it on the U-stand in the middle the back tire doesn't spin.

Adjusting the idle does seem to eliminate the problem (rpms go up?), but only if you crank it so high that a) it is abnormally, obnoxiously, clearly way too loud, and b) makes the whole bike shudder if the back tire is down and makes me think it's going to take off on me, and if it's on the U-stand it spins like it's going 20mph.

I don't know the first thing about checking the carb/throttle body, but that does sound like what's going on--not rich enough a mixture, or something is closing off when the choke goes off that shouldn't be, killing it.

I can believe that about this chinese-made PoS too. Last time I ever buy one.

 

[Raizinman]

Lifan scooters are manufactured in Thailand. They are the cheap of the cheapest scooters. Parts and service are virtually non-existent. Basically, they are disposable scooters. When they break, you throw them away. These scooters are half the price of Honda scooters or any other known manufacturer. They are half the price for a reason; it is because they are half the scooter. They use ultra-cheap parts, and parts that are not made to last or be repaired. I’ve worked on a few of these and due to unavailability of parts, I had to cut my own gaskets and fabricate a needed part. The owner was fortunate enough to quickly sell it on Craigslist to someone unsuspecting and unfamiliar with Lifan.

 

[SyndromeOCZ]

Take the carb out and clean it up good, even with a fuel filter they can get gunked up. You may also need to adjust the valves with that many miles on them. Doing that though might take some more specialty tools and knowledge on how the particular machine works.

 

[Raswan]

Lifan scooters are manufactured in Thailand. They are the cheap of the cheapest scooters. Parts and service are virtually non-existent. Basically, they are disposable scooters. When they break, you throw them away. These scooters are half the price of Honda scooters or any other known manufacturer. They are half the price for a reason; it is because they are half the scooter. They use ultra-cheap parts, and parts that are not made to last or be repaired. I’ve worked on a few of these and due to unavailability of parts, I had to cut my own gaskets and fabricate a needed part. The owner was fortunate enough to quickly sell it on Craigslist to someone unsuspecting and unfamiliar with Lifan.

Agreed one hundred percent. However, that still doesn't get me a fixed Lifan I can sell quickly.

Just a thought--you ever find yourself in OKC or around there? I notice you're from Kansas..

 

[unokitty]

Hey guys,

Fiancee's got a 2009 Lifan LF50QT-15 scooter with 1500km on it that is on the fritz. Frankly, it's given us enough trouble over the course of its lifetime that I'm ready to sell it, but need to fix this one issue first.

Here's the problem: start it up, give it a little juice, and it will idle correctly for about a minute. Then, as soon as it revs down to normal idling rpm, it will die. Keep giving it a little juice, though, no problem. You can drive it around town fine, but if you stop for a light or stop sign, you've got to keep feeding it a little throttle, otherwise it will die. Doesn't matter if you run it for 5 minutes or half an hour, same problem.

I've adjusted the idle up a little, to the point where the rear wheel brake that keeps the back wheel from spinning during idle is overwhelmed and starts spinning. Fuel filter isn't clogged, and it drains fuel fine. Shot some carb cleaner in too, put seafoam in the tank with fresh gas, same problem. Friend who's knowledgeable about motorcycles suggested the autochoke, given it's behavior.

What do you guys think? I'm a relative noob here, but I can follow directions if they are clear enough and don't require super-exotic tools. I'm willing to spend a little to fix this so I can get rid of it, but I'm sicking of it sitting outside the apartment unusable.

I'm looking around too, but any suggestions for a place to get parts would be most welcome.

Thanks in advance!

Just a guess.

Does it have a manual choke?

If I recall correctly, some of the early Japanese bikes that I had would start up and run with the choke on as long as you keep giving it gas.

However, after it warms up, it won't idle. (It will die if you try to let it idle.)

Solution is to turn the manual choke off...

Best of luck,
Uno

 

[Raswan]

Just a guess.

Does it have a manual choke?

If I recall correctly, some of the early Japanese bikes that I had would start up and run with the choke on as long as you keep giving it gas.

However, after it warms up, it won't idle. (It will die if you try to let it idle.)

Solution is to turn the manual choke off...

Best of luck,
Uno

It's an automatic electric choke.

 

[Slacker]

If I was a betting man, I'd say you have a clogged idle circuit, and that the motor isnt actually idling at all, but is only running "off idle" with the throttle.

You might be surprised how small a piece of debris could cause this.

 

[Raswan]

If I was a betting man, I'd say you have a clogged idle circuit, and that the motor isnt actually idling at all, but is only running "off idle" with the throttle.

You might be surprised how small a piece of debris could cause this.

How would I locate the source of this clog?

 

[Slacker]

Rebuild the carb, unfortunately I had no luck finding a rebuild kit for your model, there are some carbs on eBay, even a race version around a hundred bucks.

To clean the carb you have to disassemble it, when you do that you need gaskets, while you're in there replace jets blah blah blah, that's why you want a carb kit.

 

[Raswan]

Rebuild the carb, unfortunately I had no luck finding a rebuild kit for your model, there are some carbs on eBay, even a race version around a hundred bucks.

To clean the carb you have to disassemble it, when you do that you need gaskets, while you're in there replace jets blah blah blah, that's why you want a carb kit.

Fair enough. I'll wait and try the less-invasive things the others have suggested first, and then if that doesn't work consider this a next resort.

 

[The Stigenator]

clean the carbs.. the IAC is clogged. When you first start it, the auto choke opens the air circuit.

Disassemble carb / air filter, clean with carb cleaner, reassemble and reset idle.

You do not need a carb rebuild kit, just keep track of your gaskets and stuff. I use Yamaha Carb lube, but any carb lube will work. Just keep track of small 'o' rings.