Could a carb issue cause my scooter not to start at all?

I'vebeen having more and more trouble with my 49cc Roketa 26-50 2 stroke scooter. It was leaking all over when I first got it, so I fixed the leaky hoses and fuel filter. (purchased NEW)

Okay, problem solved right? Nope, everything started leaking right into the airbox. So I was told it was probably a carb issue. My engine started to hunt while driving and had trouble starting up. Wouldn't go more than 20 or 30 mph. Felt like it wasn't getting gas more than half throttle.

This morning there wasn't much leakage, just a few drops, but now it won't start at all. No kick start either. Yesterday the kickstart worked after about 8 kicks. Now I have kicked about 20 times with no start.

I loosened the bottom drain screw on the carb to drain the gas (without clamping my fuel line) and it only drained from the bowl, not my tank. Could this mean fuel isn't getting through my carb for some reason?

I ordered a new carb through the warranty but I'm just worried that this isn't even going to fix the problem. I'm missing a lot of work over this damn chinese scooter.


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Staff member
Well, I have read your other topics, and feel bad for you this chinese crap is failing on you. I still think you have to search the problem in the vacuum of the system. Somewhere there is air leaking in the system. In your other topic: I have suggested what could be a cause, but I think the only way for you is to let someone take a look who really knows his way around a 2 stroke engine. Or return it to the shop and demand a solution.

And it could be you have a vacuum valve on your fuel tank. You can check this if there are 2 hoses going to the fuel tank valve. The principle is simple. When you start your scooter there is a vacuum created in your carb, and through a second hose opens up the valve at the tank :)

But seriously, I don't think your problems are going to be fixed by replacing the carb.
I'm going to have to research what you mean by "fuel tank valve". This is my first vehicle ever so I'm learning. I did take it to a small engine shop but the guy only said "oh I know it's the carburetor, for sure. You just need to replace it and you'll be good to go."

The darn thing is getting worse and worse so at this point it requires starter fluid to crank and I couldn't even drive it to a shop if I wanted to.

I hope it is a simple carb issue but if it's not I wish I knew wth I was doing so I could check for other issues, but I'm too noob to do much diagnosing.

To be honest, I over filled both tanks pretty heavily when I first got it (of course I didn't tell the seller this) but do you think that could have jacked up something? I've since been very modest with my petrol and oil fills. The manual didn't say how much to put in. It's a Chinese manual and it didn't say jack about oil (even though the table of contents mentions that it's on page 22, it isn't.

Also, I DID switch to royal purple 2 stroke oil just before the really big problems started. Do you think that could be too rich for my engine!? I didn't think of it until just now. I figured I was doing the best thing by getting the more expensive synthetic oil.


Staff member
As long as you didn't put gas into the oil tank and oil in the gas tank there should be a problem of overfilling.

As I'm not English, what I mean with fuel tank valve is this part:

This should be at the bottom of your tank and has 2 hoses that go to your carburator and/or inlet.

Or you can have a simple version:

This has only one fuel hose to your carburator.

The first example has a valve which opens due to the underpressure created by the engine. The second example is a simple on/off fuel tap (I believe this is the correct translation?).

And the translation of the manual is funny :) Don't make the moon impatient!!! :D
I REALLY appreciate all the help. It's the best advice I've been given from anyone this far.

I didn't put gas or oil in the wrong tank BUT, it seems there is an overflow hose which drains the gas to the oil tank if it's overfilled. So unintentionally, a bunch of gas did go into my oil tank twice. (I've since siphoned both and replaced) So, do you think this could have caused my issue?

I'm still going to check the fuel valve as you suggested but if you think the gas in my oil might be the culprit what could it have done? Possibly damaged the carb?


Staff member
No, it's not a problem. The also the carb should be fine and can't be damaged by this. I think the problem lies that somewhere there is a faulty gasket between the carburator and the engine. Your problems all point in that direction. If there is a leakage, your engine will get to much air in the mixture which isn't good and you can have the problem that the vacuum generated when try to start is to low to open up your fuel tap. So look in that direction.
Yeah I just checked and everything seems secure and connected. (But I'm not an expert)

It started up but stalled almost instantly and required starter fluid to start again.

I rode it about 50 feet with no issues until I tried to give more than half throttle. At about half throttle (15mph) it sounds weirdly bogged down and muffled as it slows to a halt, finally stalling if I don't twist the throttle back down. If I let off the throttle a bit it won't stall and continues to run more or less normal.

ALSO: I check my oil and YET AGAIN there is gasoline in the oil reservoir! I have no idea how the heck that is happening!! I don't know if it's related but that doesn't seem normal at all.

So tomorrow morning I'm bring it to a different shop nearby that specializes in scooters. (assuming it makes it there lol) They're charging $35 just to diagnose the problem, so I'm worried about the cost but I HAVE to get this fixed or I'm basically screwed on getting to work and school.

Thanks again!

I'll update this when I find out what's wrong in case someone else has this issue in the future.
Finally got my scoot fixed! The repair guy only charged me 100 dollars. Not much. There is still a couple drops leaking when I go down to start her up but she's running great!

He basically just said the main problem was the gas leaking into my oil and my air filter cover wasn't on right. So, I don't fully get how that caused all my problems but it's fixed so I'm not complaining. I may return to them soon to check on that leak and make sure that isn't a symptom of something else waiting to go wrong.

A bonus was that they tightened my rear drum brake (which previously did almost nothing). They also told me my handlebars were about to fall off and they tightened em up good. I thought that looseness was normal!!

They ended up taking the fuel injector off for me and doing some modifying to the vacuum hoses and such so that the oil tank actually drains back into my gas tank.

My one question is now that I'm pre mixing what is the best ratio and isn't different for synthetic?

Right now I have royal purple 2 stroke all purpose (which I believe is SEMI synthetic. It doesn't appear to say.

I also have valvoline.

The repair man said approx 4oz per gallon, he also said it isn't going to help or hurt my scooter to use the more expensive royal purple, he suggested I stick with valvoline but I wanted a second opinion.


Staff member
Good to hear it was indeed air leakage :) Also it's a bit strange that he had to "remove" functionality to fix the problem, because it would be more interesting to see what is causing it exactly so you don't need to use premixing. But the main point it is fixed :)

Premixing ratio for a standard 2-stroke engine is 1:50 (one part oil:50 parts of gas) and the fully synthetic is preferred of mineral. They use the same mixture ratio and Valvoline is a good brand.
As the rest of the normal world uses the metric system :p I don't know how many oz per gallon it is so you have to calculate that for yourself :)
Thanks so much! The reason he removed the oil injector was due to the gas leaking into my oil reservoir. You see, the gas/oil tank on this bike are one tank seperated by a divider. That internal divider has a crack or leak which was allowing gas to go to my oil reservoir and screw my ratio up BADLY. So I have been running on an extremely lean mix this whole time.

That's the reason for removing the oil injector. We both agreed this was the safest simplest solution. Plus, he ran my oil tube back to my gas. So basically I just have a bigger gas tank now! Bonus!
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