Genuine Buddy | PGO Ligero 70cc Daily Sleeper

[broyager]

Just starting a thread to document what works for this model.

PGO Ligero / Genuine Buddy 50
Malossi Sport ported 317083
17.5mm Dellorto PHVA L-DEL1438 + b01104 + b13683
Athena Race Crank 075314 + SKF BB1B447205A bearings
KN Planning belt 651mm 7017-SS
Malossi yellow torque spring 297042.y0
Malossi reeds 0.3mm
NCY variator 1200-1050
NCY torque driver 1200-1057
Malossi Fly clutch bell
Tecnigas Silent Pro
Snorkel mod - 10mm removed from tip
85m, A27 clip middle, 33p, 2.6 turns out air/mix
6g rollers, BR8HS, 1.3mm squish, 0.4mm base
Motul 710 40:1
< 250F temps

Not a big build, and not many changes in the end, plenty of learning and tinkering though...

Just replaced the reeds and it's pulling harder now, even though there is a gap at the tips of the reeds after tightening the plates down onto the reeds. That small metal bar (nut) and screws squeezed the base of the reeds and created the gap, but I had to make them tight..... Reeds were perfectly flat themselves.

I'm still too rich I think, idle screw is over 4 turns out with a 34, and I'm getting bogging on initial take off now after replacing the reeds. It's also bogging down at idle when coming to a stop after some heavy uphill WOT.

Have stepped down on the main from 88, 86, now at 84 which feels good. 88 and 86 didn't seem to actually do anything.... ie WOT was no different than 3/4, pretty much.

I don't have a 33 which could be ideal, but will try the 32 I do have and move the clip on the needle down a notch to the middle.

75% of my commute is spent on the needle and idle jet unfortunately , so I need to tune for that range.

Stock exhaust is pretty loud.... going to try and do something about that too. I read on an MX forum you can add a small piece of pipe, same diameter, to the exhaust outlet, and point it down to the road which disperses the sound?

[micky]

sounds like a fun scooter.
I own a pgo bigmax / genuine roughhouse myself with some fun mods and they really are cheap capable machines(even if finding parts can be a hassle sometimes

The way you describe it make it sound like 32-33 range would be perfect 
If you need to turn the adjustment screw more than two and a half turns out you need a smaller pilot, but you knew that already 

Remember that lowering needle clip = more fuel. and you are bogging already 
I used to run the same carb on a streetrace 70cc cylinder and only had to change clip and mainjet to make it run crisp
i ran a 92 main jet with yazuni pipe so you should be somewhere in the 80s range when it comes to main jet size, 88 def sounded a bit rich 

Good luck with your project

[broyager]

Thanks for the reply, and reminder about that chart, that's exactly what I need to look at this point.

The reason for enriching the needle was in case the 32 idle was too small. My plug looked really good with 86, and 34, but there would be a collection of fuel/oil each time I'd come to a stop, which would have to be burned off on WOT application, not a good look for a sleeper..

I've put the 32 in, am still 3 turns out, swapped BPR7 to BPR8 and the 8 was looking a bit pale / lean, so have moved the needle up a notch for peace of mind. Temps still pretty low, and consistent. I'll see how that goes, then lean the needle a notch again if it's running ok.

The reeds have improved things generally, the original metal ones were fluttering when cruising / decelerating above 50kmh, but I wonder if they are messing with the idle.

[broyager]

I've put the needle clip back up to one step lean from the middle, and richened the idle mixture.

Idle has cleared up, more or less. Running very crisp now but also slightly hotter, especially around 1/4, 1/2 throttle.

WOT is fairly normal, but overall hitting 250F more often now, which I understand is normal.

[bigmatthew86]

250 seems still pretty rich to me. I set them to peak at 350 & don’t have any issues. You should pick up some power if you lean up some.

[broyager]

So I was 3 + 1/2 turns out on the 32 pilot to get the idle stable. I'm not sure if I have seen anyone run a 31 or lower.

Afaik a 31 would be unusually small for 70cc with dell 17.5 and stock exhaust, can anyone corroborate that?

At least I know I don't have an air leak....

I've reset the idle to 2 + 1/2 turns out, but idle is dropping to a gurgle, and it's smoking again, trying burn off all the surplus in the crank case I guess.. running cooler, but...

Maybe I just go to 3 turns, and go leaner on the main to 82. I still can't feel the main really.

Here's the plug after a few days of running the leanest I have gone so far.

[broyager]

I think it's finally sorted.

84 main, needle clip in the middle and a 32 pilot / slow. 3 turns or so out on the idle screw.

Was getting some detonation (spots on the insulator) (82main, clip 2nd from top, 34 pilot) off throttle, while the tank had some 91 in it... and running the BPR8. It wasn't too hot (250F) compared with what other's are experiencing but sounded very thin and strained when off throttle at 50kmh, like the reeds were fluttering.

I think because this is quite a torquey setup it's not needing to rev to get the power, so temp's are going to be lower, but it sounds and feels like it prefers to be richer than leaner. Idle's nicely with the 32, and I realize now that this circuit is quite independent of the needle and main. I needed to be richer at 1/4 1/3 throttle, but the idle is the idle.

Running the BPR7HS again, to help burn off that extra fuel in the 1/3 throttle range, but running with more power and cooler, at this point.

EDIT; repeatedly matched / slightly ahead of an older Suzuki Address 125 up to 60kmh from the lights the other day, that thing is 11.5hp and weighs only a few kg's heavier than mine. 4 stroke tho..

[broyager]

I was getting worried about this noise, noticeable at idle, the random clack sound.. This is with variator installed, but no weights, cvt cover on.

Couldn't find that actual noise with a screwdriver to my ear, cylinder itself sounded smooth.

Squish was measuring 0.61mm.... so off with the cylinder.

Replaced the piston with the better looking spare, along with a newer small end bearing and wrist pin, and added the metal head gasket.

Measured squish at around 1mm now.

Started up first pop, running a lot smoother now, idle is nice, much smoother at very low rpm. Not as loud / abrasive either.

Noise is still there though, not as loud potentially... need to check again.

Have lost some power I think, but didn't get the chance to WOT it yet. Changed the rollers to 6g to make up for it.

I didn't detect any play in the crankshaft, the conrod does wobble side to side, but only from the small end, I couldn't detect any noticeable side to side movement at the crankshaft end, but didn't have a good go at that really.

Anyone come across this sound before?

[aeroxbud]

Have you got any play in the crank? Side to side, or up and down?

[Kagouras]

are you sure the new small end bearing has the right dimension?

[broyager]

I'm almost certain there is no wobble in the crankshaft, but I didn't check end to end play. Will do.

The noise is definitely still there, so it can't be the top end, and 10mm is 10mm surely.

It's a 2017 model, I'm the second owner, and it's done 11,000km, so I'd think the crankshaft would be good for a few more k's than this.

It seems to be just as loud on the variator side, but a screwdriver to the cvt cover doesn't pick it up.

[broyager]

Consequentially, it's happier revving higher now that the compression is lower, and is making more power at those higher rev's, but doesn't have as much torque lower down.

I could definitely go leaner now too, probably just up a notch on the needle.

[broyager]

So... I tracked down the source of the noise i was hearing, and it's definitely coming from the piston/area.

Pretty juicy with the exhaust off..... The sound is most prominent near bottom of the stroke, heading back up to the top, and only happens if the spark plug is installed, or compression exists.

The small end bearing I installed a couple of weeks ago only has maybe 1000k's on it, possibly less, and this is the newer bearing. I had been running the original bearing, and on closer inspection of that original one, it has some scoring on one of the rollers.

There is side to side movement of the piston on the pin, but always has been, although I'm wondering if this is not how things are supposed to be?

There is minimal other movement between the piston, bearing, pin.

I have ordered a wider 15mm small end bearing today.

This is the side to side play in the conrod, I'm not sure if this is normal or not.

Crankshaft itself has zero play, in any direction.

Cylinder walls and rings look great, rings are very new, and piston itself looks ok, there is definite scuffing on one side but there is no scratching.. all the original Naraku black has work off, so it may be rubbing... I'm not sure how much is too much.

Does anyone have any advice?

Andy

[broyager]

Replaced the wrist pin bearing with a brand new wider one, and the rings, which had gone out of spec.

Did the cross hatch, hand hone with 220.

Unfortunately the noise is more constant now.... and from what I read, this is possibly piston slap??

Still making heaps of power etc, running great.

What I wonder now is whether the cylinder is being centered properly ? the holes give quite a few mm's of movement on the stud bolts. I moved the cylinder to where the piston was running the smoothest before buttoning it down, but that was side to side. Maybe it needs to go up a fraction, rather than hanging on the tops of the stud bolts?

Either that or the piston / cylinder has gone out of spec somehow

[Kaos]

Apr 3, 2023 0:17:03 GMT -5 broyager said:

Replaced the wrist pin bearing with a brand new wider one, and the rings, which had gone out of spec.

Did the cross hatch, hand hone with 220.

Unfortunately the noise is more constant now.... and from what I read, this is possibly piston slap??

Still making heaps of power etc, running great.

What I wonder now is whether the cylinder is being centered properly ? the holes give quite a few mm's of movement on the stud bolts. I moved the cylinder to where the piston was running the smoothest before buttoning it down, but that was side to side. Maybe it needs to go up a fraction, rather than hanging on the tops of the stud bolts?

Either that or the piston / cylinder has gone out of spec somehow

You shouldn't have much movement on the studs. Are you sure the holes didn't get hogged out somehow?