2013 Buddy 125 intermittent power loss

[baldachi]

14,000 miles. Belt and rollers replaced at 8,000. No mechanical issues ever. It starts easily, accelerates normally. At about 32 - 35 mph it loses rpms as if it's trying to stall. Goosing the throttle brings no immediate response, but it eventually recovers. I get the same issue at about 42 - 45 mph. The engine never actually stalls out, and the power loss seems to occur only in those two
speed ranges.

I'm looking for any educated guesses as to likely cause. My uneducated guess is carburetor-related.

[buzzvert]

I'd start simply- add some seafoam to the gas and replace the fuel filter. If no change after a bit, remove and service the carburetor, cleaning the jets, making sure the float is working correctly etc...

I agree that it sounds fuel system related.

[JettaKnight]

Could very well be electrical. Does it recover if you let the throttle close?

[tenders]

Is this a carb, or fuel injection? Agree this sound like a fuel issue would be a good place to look carefully.

I would check the spark plug for tightness, and replace the coil and spark plug wire as a matter of maintenance at 14k miles too.

[Stanza]

If it's a regular buddy 125, you might also have a plugged gas cap vent. Take it on the same route where it usually does this, but unscrew the gas cap partway so air can get in. If that solves, it, you've been dealing with vacuum lock on tank.

[DeeDee]

Check for deterioration of your carb diaphragm. At 14,000 miles things start to wear out. When is the last time you adjusted the valves. They should be checked every 4,000 miles. Some rarely need adjusted, others need more attention.

[tenders]

^^^ good suggestion from DeeDee. That’s on the other side of the carb from the jets that you need to clean, easy to overlook.

[baldachi]

[quote="JettaKnight"]Could very well be electrical. Does it recover if you let the throttle close?[/quote]

I did not recall specifically, so took a ride to ascertain. Closing the throttle had no effect. The power loss seems to occur somewhat randomly. Sometimes I can accelerate to speed from a stop with normal operation. Other times, the power loss ensues at about 30 mph. If I do get beyond 30, the power loss occurs between 40 - 45, but not every time.

[babblefish]

Mine does the same at times, but very infrequently. Engine starts to sputter then just dies. It will usually restart without any problem and continue running fine thereafter. Strange. I'm thinking it might have something to do with the stator since the power and timing for the ignition coil comes from there. Might be a good time for me to experiment with converting over to an 11-pole stator. If it works it'll give me more power for add-on electrical accessories too.

[buzzvert]

Mine does the same at times, but very infrequently. Engine starts to sputter then just dies. It will usually restart without any problem and continue running fine thereafter. Strange. I'm thinking it might have something to do with the stator since the power and timing for the ignition coil comes from there. Might be a good time for me to experiment with converting over to an 11-pole stator. If it works it'll give me more power for add-on electrical accessories too.

That actually brings up a good question regarding stator poles. Does quantity matter? As long as it fits the mount, is the assumption "more poles = better"? Does it matter from a timing perspective?

I just fitted the NCY stator and it looks identical to OEM although the sensor is a different form factor and looks a lot beefier. Seems to work fine. In digging around, PGO seems to have fitted a pretty junky chinese OEM part and while a lot last the life of the bike, many crap out well under 5000 miles in just the manner you noted- occasional full-on death that gets more and more frequent. It's a cheap and easy upgrade (as long as you invest in a flywheel puller!) and I'd lump it in with any new-to-me bike preventive maintenance from now on.

[babblefish]

Mine does the same at times, but very infrequently. Engine starts to sputter then just dies. It will usually restart without any problem and continue running fine thereafter. Strange. I'm thinking it might have something to do with the stator since the power and timing for the ignition coil comes from there. Might be a good time for me to experiment with converting over to an 11-pole stator. If it works it'll give me more power for add-on electrical accessories too.

That actually brings up a good question regarding stator poles. Does quantity matter? As long as it fits the mount, is the assumption "more poles = better"? Does it matter from a timing perspective?

I just fitted the NCY stator and it looks identical to OEM although the sensor is a different form factor and looks a lot beefier. Seems to work fine. In digging around, PGO seems to have fitted a pretty junky chinese OEM part and while a lot last the life of the bike, many crap out well under 5000 miles in just the manner you noted- occasional full-on death that gets more and more frequent. It's a cheap and easy upgrade (as long as you invest in a flywheel puller!) and I'd lump it in with any new-to-me bike preventive maintenance from now on.

More poles = more amps generated. Battery charges faster, more reserve amps to power things like brighter headlight, more lights, sound system, heated gloves, heated vest, etc. The 170i engines all have 11-pole stators because the EFI and electric fuel pump needs more amps to work properly.
Only one pole supplies power to the ignition coil. It is the one that is covered with either black or white tape. The ignition trigger sensor is also part of the stator wiring harness though it doesn't generate any power, it just tells the CDI when to trigger the ignition coil which in turn makes the spark in the spark plug. The ignition trigger sensor is that little black module that sits next to the magnetic rotor. On the outside of the rotor is a small square metal block that passes close to the sensor once every revolution of the crankshaft. The location of that metal block determines your ignition timing which I believe is around 4 degrees before top dead center of the piston.

Converting isn't just plug and play though. The stock 4-wire voltage regulator will have to be changed to either a 5-wire or 7-wire voltage regulator (my research makes me lean toward the 5-wire) and the wiring harness modified.

Hope that explanation wasn't too confusing or too basic for you (I don't know your knowledge level).

As far as quality, yes, there are differences hence the varying prices they are being sold for. On some of the really cheap ones the windings are either a really thin gauge copper wire or worst, aluminum wire. Some of the really cheap stators also come pre-rusted so you don't have to wait for mother nature to do her thing.

[buzzvert]

This all makes sense- thanks. Also tells me I can look at the voltage regulator on a generic GY6 to tell which stator it has under the flywheel. Which saves me some time, as I have to order a new claw-style flywheel puller for a friend's Chinese bike- the threads on his flywheel are buggered up so bad the center puller just pops right out. Now I can order both at the same time.

In looking at the NCY again vs. stock- I see your point. The NCY stator has much beefier copper gauge on the coils.

[baldachi]

Thank you to everyone who responded to my original post and dilemma. I will try to apply the constructive advice - and sift out the superfluous babble.

[buzzvert]

sift out the superfluous babble.

Hey it was MARGINALLY related!

(still putting $5 on the stator being the issue but the gas vent is a damn good suggestion too)

[tenders]

Thank you to everyone who responded to my original post and dilemma. I will try to apply the constructive advice - and sift out the superfluous babble.

The editorializing, really? Seems like you got quite a lot out of this considering what you put in.