Cranks up, then dies

[wheelbender6]

I have the opposite problem of Ego. My scoot runs great at cruising speed, on the main jet, whether the engine is warm or cold.

Runs good initially, for ten minutes or so. Then it will not idle and stalls. It will crank up but quickly stalls.

If I let it cool off for 20 minutes or so, it runs well again for a few minutes.

I have adjusted the valves and swapped in a spare CDI box I had. Same result.

The scoot sat for about 4 weeks.

Do I need a carb cleaning or is there something else I can try?
Thanks

[scootERIK]

Carb cleaning is probably the best place to start but you could try putting some Seafoam or other carb clean through it(and some fresh gas, premium no ethanol ideally.)

Just going by your description it sounds like the idle jet is clogged but it is able to run when the auto choke is on but when the auto choke turns off it doesn't get enough gas(but I could be wrong.)

[wheelbender6]

I have added the sea foam and have attempted 2 rides since.

Looks like I will be pulling the carb for cleaning.
Thanks

[wheelbender6]

Pulled the carb today and cleaned it. its the first time I have done a carb cleaning.
Went pretty easily except there were a couple of stuck screws. The elec choke screw and float
retaining screw were really tough to remove.
I used a strand of bicycle cable to rooter the passages and jets. Gumout spray carb cleaner.
Got her reassembled, reinstalled and I will try it out in the morning.
Hopefully, my IMG links will work.

[tenders]

Those soft brass screws and jets can really get mangled unless you use the right tool. For carbs I have a few cheap-ish flathead screwdrivers that started out longer than the slot but are thick enough to fill the slot well. I then cut down the edges of the blade with a Dremel so they fill the slot completely. I press down very hard and turn the handle resolutely.

[wheelbender6]

Details like tenders mentioned above really that matter. I used an impact driver once on a float bowl screw. Cracked the plastic top cap of the carb and had to replace it.
You never get on the main jet (i.e. get above 35 mph) with a cracked top cap, LOL.
-I wont use my every-day screw drivers and bits on a carb. Buying a few fresh screw drivers will save you money when doing carb work.

[wheelbender6]

The scoot runs the same after my carb cleaning. Starts and runs well with the choke on. Stalls and wont idle when warmed up.

During the cleaning. I never could push a wire all the way through the pilot valve. I can see light when looking through it, but the wire wont push through.
??Would replacing the pilot valve help my idle problems?
??Should I disassemble the carb again and soak the parts in carb cleaner longer, like all day?

[wheelbender6]

What is the best way to order the correct stock pilot jet?

Should I search for a Keihin 22 series?

Some seem to call it a slow jet.

I want to be sure I get the right one.
Thanks

[wheelbender6]

The video I watched before my first attempt at carb cleaning was generic.
-The vid at the link below from scooterwest is specific to the Buddy 125, so it has likely been posted here before.
It tells you which parts that you should be able to pass the cleaning wire all the way through and which ones you can't.
-While watching the video, I learned of at least two circuits where I was not able to pass the wire through, but I should have been able to.
Plenty of do's and dont's; and it covers re-installation too. I wish I had seen this vid before my first attempt.
https://www.youtube.com/watch?v=CD-nPIajHAQ

[wheelbender6]

If I decide to get a new stock pilot/idle/slow jet, looks like it needs to be a Keihin #38.

[scootERIK]

If I decide to get a new stock pilot/idle/slow jet, looks like it needs to be a Keihin #38.

I will try to check my jets tomorrow to see what size they are, offhand I think 38 sounds right.

And from what I can remember you can only see through one of the jets, but I will check that too.

[scootERIK]

The scoot runs the same after my carb cleaning. Starts and runs well with the choke on. Stalls and wont idle when warmed up.

During the cleaning. I never could push a wire all the way through the pilot valve. I can see light when looking through it, but the wire wont push through.
??Would replacing the pilot valve help my idle problems?
??Should I disassemble the carb again and soak the parts in carb cleaner longer, like all day?

I just went out and checked some of my jets. The stock idle jet is a 38. I was only able to push a wire through the length of the jet if I inserted the wire on the end with the screwdriver slot. From the other side I wasn't able to get the wire to go through. I was using a guitar string, either a 9 or a 10.

EDIT: After an hour in an ultrasonic cleaner I was able to push a wire through in both directions. I was even able to go to the next size larger string, ~.012 or .013. But I think the larger only went through from the screw side.

[wheelbender6]

Thanks, Erik. The guy in the scooterwest vid was able to push a really fat wire through his pilot jet after cleaning.

I will try a few more things before buying an ultrasonic cleaner. A small ultrasonic cleaner is still less than half the cost of a new carb.

[scootERIK]

Thanks, Erik. The guy in the scooterwest vid was able to push a really fat wire through his pilot jet after cleaning.

I will try a few more things before buying an ultrasonic cleaner. A small ultrasonic cleaner is still less than half the cost of a new carb.

A long soak in some carb cleaner might loosen up the gunk. Then start by pushing the wire from the screw side, it seemed to be easier for me to get the wire through that direction.

I got lucky and bought my ultrasonic cleaner at a garage sale for $1, but you can get similar for $12 to $18 new. It's a small battery operated unit. It's probably not as good as a real one but it seems to have helped the few times I have used it. But even at $12-18 it would be cheaper to just get a new jet, I think the last ones I got from the local dealer were $5 or $7.

[BayStateScooterist]

The video I watched before my first attempt at carb cleaning was generic.
-The vid at the link below from scooterwest is specific to the Buddy 125, so it has likely been posted here before.
It tells you which parts that you should be able to pass the cleaning wire all the way through and which ones you can't.
-While watching the video, I learned of at least two circuits where I was not able to pass the wire through, but I should have been able to.
Plenty of do's and dont's; and it covers re-installation too. I wish I had seen this vid before my first attempt.
https://www.youtube.com/watch?v=CD-nPIajHAQ

I came across the same VID from Scooter West during my quest for fuel line replacement parts. Very detailed steps, will refer to when I need to clean the carb. Found the fuel line replacement parts I needed from Scooter West.

[tenders]

I have a Harbor Freight ultrasonic cleaner, and like it. Lots of YT videos on how to make the most of it. Used it on Sunday to sizzle the grime off of my Scarabeo’s old, leaking, and replaced brake caliper - I might be able to rebuild it. But you do have to set expectations; it doesn’t always work magic on carbs.

I’m only familiar with the carb in the 50 so don’t have anything specific to offer here. JetsRUs is one of the few places that stock the unusual “PB series” size of jet for that carb, which is the line that Keihin uses for manufacturer-specified carbs (and not specced by Keihin). I don’t know if the 125cc carb is related to the 50cc carb. But the stock idle jet on the carbed Vespa 150 “Leader” engine is size 35, and is often recommended to be upgraded to 38 for better takeoff.

[wheelbender6]

I bought one of the Harbor Freight Ultrasonic cleaners last night. I ran my carb through it twice this morning, long cycles with heat.
-Pilot jet is still clogged up. I have ordered a new one from jetsrus.
-That brass tube in the venturi (5 o'clock position in the attached pic) is also still clogged.
I can penetrate it with a wire further after the ultra cleaning, but I need to keep working on it.
Not likely that my Buddy will be running this weekend.

[tenders]

Pic didn’t come through. What cleaning solution are you using in the ultrasonic cleaner? I use 2:1 or 3:1 water:Simple Green, which works ok but makes aluminum turn a dark gray color. I don’t think it dissolves corrosion, which may be the problem with some clogged jets, but does a good job on dirt and petroleum remnants of various types.

[Racer50]

I use jewelry cleaning solution to soak my jets in. After 10 minutes, they are bright brass. Not sure if this stuff is available anymore, I found it in a box of free stuff.
I use micro90 for us cleaning carbs, but I find that Gunk carb soak is more effective at cleaning the small passages. The 1 gal. Can has a basket for soaking small parts. It will clean jets fairly well, followed up by the jewelry cleaner and carb spray. I use a piece of 16 AWG stranded wire, pressing as many strands as possible into the jet and carb passages to verify flow-thru.

[wheelbender6]

I don't know why my photo does not appear. Maybe I need to reduce the file size.

I used the cleaning solution from harbor freight during the ultra cleanings. They recommend a 1/4 teaspoon of cleaning powder per 2.5 liters of water.

I have heard from others that simple green works well in these ultra cleaners for mechanical parts.

I have also followed up the ultrasonic cleanings with more carb cleaner and wire. I will have this thing running soon enough.

[wheelbender6]

Installed the new jets and attempted to start it.
It just spun like a washing machine.
Checked for spark. Oops. Bad plug.
Swapped in the plug from my wife's Buddy and it fired up.
It idled well with the choke off. Alas, too dark for a test drive.
Finally!