Espresso 150 cuts out when throttling

[Afro Boy]

Hiya,

Just got a second hand Kymco Espresso 150. Only done 1000kms and is very good nick with RWC and recent service. Got it home and am finding that it starts ok, but when I hit the throttle it cuts out suddenly. There is no spattering or chocking kind of action, just a sudden drop dead.

I can hold the throttle at a very low power to get the back wheel spinning (on the stand) with no troubles, but as soon as I give it a little more (even slowly) it cuts off.

So far I've checked the air filter and that all looks very clean. I adjusted the idle but no luck there either. Found the spark plug but can't get the damned thing out to check it as it's screwed in quite tight and is difficult to reach. All the lines look good with no cracks. I'm not very good with mechanical things (wooden things, no problems though!) so any advice or thoughts would be great.

I'm hoping to bring it into a service centre but everywhere seems closed until the new year.

Any thoughts?

Cheers,

Af.

[Vivo]

Sounds like fuel starvation. Have you checked for bends, clogs, or any restrictions at all in your fuel lines? I'm not familiar with your scooter. Does it have a fuel petcock that might be partially closed? Clogged or dirty filter?

[Afro Boy]

Thanks so much for the quick reply Vivo. I really appreciate it. Fuel starvation is most likely the issue here I agree (based on my limited knowledge of these things).

Checked ...

• Air filter is very clean
• Fuel lines have no kinks that I can see
• Fuel cap on/off makes no difference

I found the pilot screw and made a few adjustments but it didn't seem to have any impact at all to the RMP at idle that I could hear, except when it was almost closed. I've returned it to the original setting.

I've put up a video to hopefully help diagnose the issue. I can focus in on particular areas if it helps. Just be my guiding hands!


Cheers,
Af.

[old geezer]

Carb needs a good cleaning. One of the jets is probably partly stopped up.

[Afro Boy]

Thanks. So short of rebuilding the carbi, how do I go about getting a cleaner into it? I have some carby cleaner here but not sure where exactly to spray it into?

The instructions say to take the air cleaner off which I can do (that's the large pipe going from the air filter to the carbi). Then it says to spray in burst inside the carbi throat. Is that where the air cleaner pipe joins to or somewhere else? 

I have the kymco service manuals here so could probably pull apart and rebuild the carbi but I'm trying to avoid that if at all possible.

Thanks,
Af.

[old geezer]

You don't need to rebuilt it, just dissemble it and spray out all the jets and passages.

[Vivo]

Try sea foam or other carb cleaners. There are at least two types. One you spray while the engine is running and continue spraying while you rev the engine. The other one you spray while engine is off and let soak for several minutes, let dry and start the engine. Don't limit yourself to motorcycle shops or stores. Go to auto shops also. Carb cleaner and other chemicals have universal applications either for cars or bikes. Motorcycle specific products are sometimes ridiculously priced very high.

[jprestonian]

All of the above suggestions are good ones, but I like starting with the simplest thing first. And the symptoms you describe are all potentially caused by what people have pointed out, so far. But it's also a symptom of an air leak near the carb, which is dead-easy to diagnose.

Go to the auto parts store and buy a can of starting fluid (main ingredient is ether -- very flammable!). Remove the bolts holding the seat bucket in, and lift seat and bucket out of the scooter, and set aside. Start the scooter. Using the little straw that came with the starting fluid, spray tiny, half-second bursts around the plastics on either side of the carb. If you find a place where you spray that causes the engine to rev higher, spray a little more, there. If that makes even MORE revs, you just found a leak. Fix that (repair crack, or tighten clamp), and continue the half-second sprays to see if there are any more leaks.

Hope that helps!
.

[Vivo]

All of the above suggestions are good ones, but I like starting with the simplest thing first. And the symptoms you describe are all potentially caused by what people have pointed out, so far. But it's also a symptom of an air leak near the carb, which is dead-easy to diagnose.

Go to the auto parts store and buy a can of starting fluid (main ingredient is ether -- very flammable!). Remove the bolts holding the seat bucket in, and lift seat and bucket out of the scooter, and set aside. Start the scooter. Using the little straw that came with the starting fluid, spray tiny, half-second bursts around the plastics on either side of the carb. If you find a place where you spray that causes the engine to rev higher, spray a little more, there. If that makes even MORE revs, you just found a leak. Fix that (repair crack, or tighten clamp), and continue the half-second sprays to see if there are any more leaks.

Hope that helps!


Agree! This happened to my Honda Cub before. The leak was caused by a crack at the intake manifold spacer which was made of plastic. Caused by overtightening of the carb bolts.
.

[Afro Boy]

Thanks to all of the suggestions ... I got it running!!! Woo Hoo!

Aside from replacing the spark plug (which was somewhat blackened), I dismantled the carbi as shown in the video, cleaned it all out, put it back in, tightened everything up and gave it a start. Within 30 seconds it was revving beautifully. I will still check for air-leaks as it's something I should probably now that I've just put together my first carbi.

Thanks again for all the support, ideas and help.

Cheers,
Af.

[Vivo]

Congratulations man! You're welcome anytime!   

[jprestonian]

I will still check for air-leaks as it's something I should probably now that I've just put together my first carbi.

Probably no need, if it doesn't want to die when you give it throttle. However, keep it in mind if you ever have those symptoms, again. Starting fluid/ether keeps well in the pressurized cans, and it's pretty inexpensive (or it is here in the U.S. -- maybe $3), and will last for many, many such diagnoses.
.

[roboscoot]

glad you got it running.....stay on top of that carb....