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Post by kyalami321 on May 20, 2015 8:47:47 GMT -5
Hey everyone,
I've got a 50cc Mojito that I purchased from a guy who installed a Leo Vince Touring pipe on it, adjusted the carb accordingly, and desrestricted. The scooter is wild fast compared to stock (as described on the Net), running through the powerband up to 35mph and then steadily accelerating to an absolute max of 52mph. If I've got wind in my favor, I can keep a steady 40-45mph with only about 1/4 throttle open.
The other day, I was on an empty street going about 41, 42mph steadily for 3.5 miles (as per Google Maps). At the end of those miles, the scooter cut out and turned off. I pulled over and tried to restart it with the electric start and kickstarter. No dice until about 20 minutes later, when it turned on and then got me home with no issue, although the streets from that point on were constantly interrupted by red lights.
Is my scooter overheating? During that long stretch, the throttle was only about 1/4 to 1/2 open; should I have kept it wide open in order to keep the cylinder lubricated?
Please help! Thanks, Tomas
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Post by ramblinman on May 20, 2015 9:52:41 GMT -5
i would pull the spark plug.  post some pics of your plug if you're not sure. |
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Post by murkyapricot on May 20, 2015 12:55:36 GMT -5
Could it be that the valves are too tight?
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Post by kyalami321 on May 20, 2015 16:23:14 GMT -5
Thanks for the suggestions, I will pull the spark plug tomorrow and check it out. What valves are you referring to?
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Post by onewheeldrive on May 20, 2015 17:18:02 GMT -5
Pretty sure it's a 2-stroke, it doesn't have valves to adjust.
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Post by geh3333 on May 20, 2015 21:47:31 GMT -5
Thanks for the suggestions, I will pull the spark plug tomorrow and check it out. What valves are you referring to? It sucks these scoots don't have temp gauges installed ! I recommend purchasing one , even it that's not the issue. Even one of the oil dipstick ones will work just fine. |
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Post by kyalami321 on May 21, 2015 13:23:39 GMT -5
Pretty sure it's a 2-stroke, it doesn't have valves to adjust. Yup, 2-stroke with an oil pump so no pre-mixing is required. Scoot does it by itself |
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Post by kyalami321 on May 21, 2015 19:42:15 GMT -5
Hey so I pulled the spark plug and this is what it looked like. I believe it's erring on the side of rich given brownish decoloration, so although the symptoms pointed to leanness I believe the carburetor is actually fine. Could it be a fuel delivery problem? The fuel sending unit shows a small crack but nothing comes out even with a full tank. It's a gravity fuel feed, so maybe there's a vacuum problem? I replaced the spark plug with a new one, appropriately gapped and anti-seized on the threads; I'm going to go for another long ride and see what's up.  |
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Post by cyborg on May 21, 2015 21:02:55 GMT -5
Is it injecting oil correctly?',,,oil tank have oil?,,,, almost sounds like a soft seize,,,and also when it shuts off check the fuel tank cap,,,if it sucks air it's a venting issue with the fuel tank,,,also if your riding pinned wfo the auto vac fuel tap may be closing from lac of vacuum,,, had that exact issue with a scoot on another forum last week
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Post by kyalami321 on May 29, 2015 14:49:09 GMT -5
Hello everyone,
I will be checking up on the scooter again tomorrow at the local shop. It hasn't quit on me, but I haven't taken it on rides similar to the one where it produced an issue - don't want to produce another problem without a professional opinion. I now notice a weird vibration coming from the engine area that increases when idling and decreases when accelerating. I will post results from the work soon.
Thanks!
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Post by steve on May 31, 2015 9:58:48 GMT -5
When I upjetted, I had the same problem. After much swearing, and trial and error, I finally solved the issue. At certain speeds( right around 40 mph), the fuel valve would close, due to lack of vacuum. The reason fuel wasn't coming out of the fuel valve you talked about is that they require vacuum from the engine to open them. That's why there is 3 hoses on them. One is a vacuum line from your manifold.
You can do 1 of 2 things: You can purchase a Mikuni vacuum fuel pump for about $40, or you can do as I did. I bought a manual shut off from the auto parts store. I just leave it on all of the time. One less thing to worry about. If you have a petcock that is screwed into your gas tank, that makes is a little more tricky. Those things are notoriously bad about malfunctioning. The diaphram fails on those, and gas goes through the vacuum line into the cylinder. It can lock your engine up.
You could unscrew it, and find a plumbing part from the hardware store that would work, I assume.
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Post by geh3333 on May 31, 2015 22:11:52 GMT -5
When I upjetted, I had the same problem. After much swearing, and trial and error, I finally solved the issue. At certain speeds( right around 40 mph), the fuel valve would close, due to lack of vacuum. The reason fuel wasn't coming out of the fuel valve you talked about is that they require vacuum from the engine to open them. That's why there is 3 hoses on them. One is a vacuum line from your manifold. You can do 1 of 2 things: You can purchase a Mikuni vacuum fuel pump for about $40, or you can do as I did. I bought a manual shut off from the auto parts store. I just leave it on all of the time. One less thing to worry about. If you have a petcock that is screwed into your gas tank, that makes is a little more tricky. Those things are notoriously bad about malfunctioning. The diaphram fails on those, and gas goes through the vacuum line into the cylinder. It can lock your engine up. You could unscrew it, and find a plumbing part from the hardware store that would work, I assume. I also recommend a manual shutoff valve instead of the vacuum valve. I've had one on for nearly 4 yrs now. |
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Post by kyalami321 on Jun 3, 2015 22:08:03 GMT -5
Thanks for the help so far everyone. Where can I buy and how can I install the fuel pump? It would make sense for fuel delivery to be the issue because sometimes I simply don't feel reaction to throttle action. I'll slow down to take a turn and then try to spring back to 40 mph from about 17 or 20 mph and it just takes forever, but not because I'm impatient. It takes forever because the engine is simply not working at WOT-like RPMs.
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Post by kyalami321 on Jun 4, 2015 16:36:47 GMT -5
The guy who sold me the scooter is a Honda mechanic and he suggested drilling a small hole in the gas cap to eradicate vacuum issues. Thoughts? How big a hole?
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Post by geh3333 on Jun 5, 2015 2:10:31 GMT -5
Thanks for the help so far everyone. Where can I buy and how can I install the fuel pump? It would make sense for fuel delivery to be the issue because sometimes I simply don't feel reaction to throttle action. I'll slow down to take a turn and then try to spring back to 40 mph from about 17 or 20 mph and it just takes forever, but not because I'm impatient. It takes forever because the engine is simply not working at WOT-like RPMs. A gravity fed system does not need a fuel pump. The carb bowl can only hold so much fuel before the float slows the flow down. I would get rid of any vacuum operated fuel valve and replace it with a manual shutoff valve. I never close mine unless I am doing any type of work where I need to shut the fuel flow off. The float in the carb will shut the fuel flow off when the scoot sits. Or you could shut it down every time your not riding , what ever you prefer. A fuel pump on a gravity fed system is like installing another front brake lever somewhere on the scoot and pulling both at the same time. |
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