Modern Buddy

Hello Everyone. This is my first post here. I am here because my 2013 Buddy 125 started to sputter and stop when driving at say 35-45 mph. It ran normally at slower speed but the moment it got up to high speed it would sputter and stop.

I pulled the carb and gave it a good cleaning. I replaced the fuel filter. I put it back together today and the problem persists. I discovered that one of the lines (maybe a vacuum line?) is disconnected at the end that is not attached to the carb. Photo below of the spot on the bottom of the carb where it attaches.

Any idea where the other end is supposed to connect? Thank you!

That hose is a drain hose for the carb, if you turn that screw above your arrow in the picture it will drain the float bowl.

-Did you inspect the diaphragm in the carb? You need to make sure there are no holes in the rubber.

-Could you have overfilled the gas tank?

-Is your sparkplug cap on tight?

-Has it been sitting?

-How many miles on the scooter?

-Does it rev up properly on the centerstand?

-Does it only die at speed? Or will it die at other times?

-Has the scooter been harder to start?

Thank you for your reply. That makes sense. To answer your questions.....

The diaphragm inside the carb is intact and perfect.
The gas tank filled to below half at the moment.
I did a turnup and changed the spark plug. I checked the cap while doing so and it fits tightly.
We use it four or five times a week. We are in Southern California.
It has about 3500 miles on it.
It revs perfectly on the center stand but I can reproduce the problem (cuts off) at high RPMs.
It seems to die at speed the first time. If I don't let it sit for a while and try to restart it right away, it will then die at slow speed as well. I believe the problem is gas starvation.
The scooter has always started right away without hesitation. I changed the battery two months ago.

Next step is double checking all the vacuum lines. Maybe the petcock valve?

You have checked all the things I would check so now you have me stumped.

At this point I would make sure the air filter and intake hoses are clean. You could also go through the carb again just to make sure you got everything.

Hopefully another Modern Buddy member will have some other suggestions for what to look at.

I agree that ruling out a vacuum or petcock problem would be the next logical step. If vacuum weren’t pulling the petcock valve open properly, partial fuel flow could explain your symptoms very easily.

tenders wrote: ↑Sun Feb 06, 2022 1:27 pm I agree that ruling out a vacuum or petcock problem would be the next logical step. If vacuum weren’t pulling the petcock valve open properly, partial fuel flow could explain your symptoms very easily.

Good. Thank you level heads.

Buying the petcock today. I will update when it is installed.

Okay, it seems like good vacuum getting to the petcock. I replaced it anyway. It did not solve the problem. Gast tank is clean. I am stumped.

If you’re certain the fuel line from the tank to the carb is intact - they can decay from the inside where you can’t see it easily, I would just replace it - then it sounds as though you have a problem inside the carb. The tip of the needle valve may be getting stuck in its passage and not letting a full flow of fuel into the bowl. The metal tab that presses the valve into the passage based on the float height might be bent/misadjusted so that as the carb bowl empties, the needle valve doesn’t open the passage enough to let enough fuel in to replenish what gets used at higher speeds. Or some kind of gunk might still be lodged in there, restricting flow despite the fact that you cleaned it - actually the most likely situation if this really did start out of the blue.

If it runs indefinitely at lower speeds and only cuts out after a while at high speeds, this is what I’d rule out next.

Yes, I replaced the full length of the fuel line including the filter. I will work on the suggestions. Thank you.

Any updates on this issue. I have a similar issue. I see that in another post (link below) they had mentioned the stator needing cleaning / replacing.

link to thread where STATOR was mentioned:
viewtopic.php?f=1&t=31371&sid=8e7024845 ... 288a09bf9a

You would be better suited to start a new thread with your problem. There is a whole list of things you should troubleshoot with these symptoms before you start looking at the stator. How many miles on the bike? Did it sit unused for a long spell? What recent work has been done to it, etc...?

Ego wrote: ↑Tue Feb 08, 2022 10:09 pm Okay, it seems like good vacuum getting to the petcock. I replaced it anyway. It did not solve the problem. Gast tank is clean. I am stumped.

New vacuum hose as well? Gotta have tight fittings and good hose.