Starts but dies when throttled

[webslappy]

As part of the repair I had done at the end of the season, they put in a new spark plug. I can get it to start but as soon as I hit the throttle, it just dies. I just finished draining the gas and emptying the carb bowl. Put in fresh gas with octane boost and it does the same thing. Pulled the plug and it looks like this which I'm pretty sure it shouldn't. Any suggestions on things to try is greatly appreciated. Thanks.

Spark plug pic:

[scooterfan]

It could be caused by clogged jets in the carb. Did you make sure the carb jets are clean ?

[webslappy]

I didn't get that far yet, but from your reply that sounds like my next step. I don't know much about engines but as long as I can find a video, I'm game to give it a whirl. Thanks for the info.

[Stig / Major Tom]

What was the nature of the repair last season?
Was it running then?
Stig

[Iahawk]

i just posted about a similar problem, recently.  http://www.kymcoforum.com/index.php?topic=27834.0,  titled 'pilot jet question' in the General Discussion area.

if it starts then dies when you give it a little throttle it is very likely your pilot jet. I just cleaned my pilot and main jets recently. Totally solved the problem of stumbling off idle. I'll attach a pic of mine. In the pic I unhooked my carb enough to fip it over and remove the bowl  to get to the jet. You'll need a VERY small wire to get through the hole in the pilot jet. I used a wired from a wire brush but the wire from a bread twist tie may work. You'll also need a spray can of carb cleaner. The yellow arrows in my pic are attempting to point to the pilot jet.

Do a search on youtube for GY6 150cc carb cleaning. Plenty of them..

[webslappy]

What was the nature of the repair last season?
Was it running then?
Stig

Stig, I had another post last year where my scoot was at the mechanics all summer and got it back just in time to put away. The mechanic replaced the stator wire and CDI unit and it seemed to have fixed it (at least in my 1min test in 30 degree weather).  That issue was bogging down at high speed and this is cutting out when throttled. As I type this, it makes me think the issues may be related because they're both under throttle conditions. Does that seem like a logical conclusion?

[webslappy]

Thanks, lahawk.  I'll do the carb and pilot jet clean as my next step.

[webslappy]

Since I have limited engine experience, I bought a used donor carb on eBay for $10 that I'll use as my patient.  I'll let you know how it goes.  Thanks for all the tips.

[webslappy]

Thanks for the help. I pulled the carb, cleaned it and reinstalled it. Fired right up. No more stall when throttled.

[Iahawk]

Excellent! Did you clean the entire carb...just the jets...?....and this is the first time you've ever worked on a carb?

[webslappy]

Yep, first time working on a carb. I removed the whole carb and intended on doing a thorough cleaning but got a little intimidated by the whole thing so I just cleaned the jets and one was completely blocked so I was hopeful that was my problem and it was. Thanks again for your help.

Related question. Is there an additive I can add to the gas to help keep the carb cleaner longer?

[CROSSBOLT]

Yes, non-ethanol gas! Or ride every day! Or both!

[webslappy]

Can I just add ethanol remover like my brother does for his boat engine?

[Iahawk]

I’ve always run non ethanol gas with marine stabil (the blue stuff) in every tank...and my carb jet still got plugged. I think it’s just the nature of the beast..especially if it’s not ridden regularly. My problem is my scooter may sit for 1-3 weeks between rides. I’ve thought about starting to take 2 extra minutes and just drain the carb bowl after each ride....but haven’t done it, yet!

[KymcoRockr]

Use tier one gas from a busy brand name station. The more crap you add to it out of bottles, the more likely you are to cause problems. If you read enough forums, you will start to notice a couple of things. One is that most photos of epic variator failures feature Dr. Pulley sliders, but they usually don't get the credit they deserve.  Another is that most of the problems with gas are experienced by people who "improve" things by adding stuff to the tank. Do you think people in Asia or Europe who ride these things thousands of miles a year are putting magic sauce in the fuel?

An excellent thing to clean carburetor jets with is the smallest guitar string. It will go through anything and you can buy a lifetime supply for about $6.