Genuine Buddy | PGO Ligero 70cc Daily Sleeper

[Kaos]

Apr 17, 2023 1:22:42 GMT -5 broyager said:

Another question, should there be a lump in the rotation of a crank which isn't connected to anything, or should it be smooth? Oil pump is still connected in this example.

Lumps are BDC TDC pretty much

I have a solution in play, a complete crankcase from a PMX 50 for $90NZD. The gears might be taller... I realize now, but I can always just put some lighter weights in. i have some 5g's rollers in good nick. Or is it the other way around? PMX has the 12" wheels I think?

Still riding it nervously, the clack seems to be changing into a lighter tick... so.. who knows. I know that the small bearing, wrist and clips are all new, and it's not overheating at all so, will take my chances for now...

That looks pretty normal, you still have your stator on there and there's some pretty big magnets in the stator that can cause that to happen. I wouldn't worry about that.

If you're sticking a 10 inch wheel on a 12 inch wheel engine the gears get STEEPER not taller. Not always a bad thing, you'll get off the line a lot faster.

[broyager]

Cool, thanks a lot for the info.


That's actually perfect, I care little about top speed really, all speed limits are 60k's where I live, I have to go out and find the 2x 70 and 80k zones, and they are short.....

[broyager]

So.. of course the 12" wheel case is longer than my 10".. shock and brake cable probably wouldn't have reached, and I didn't get the CVT cover with it. And the crank wasn't spinning that freely.

In any case, I made a flywheel puller, split both cases, or should I say 'adventures with a heatgun and a rubber mallet'..

The old crankshaft was definitely binding, did not spin freely once everything had been removed from the shaft.

Swapped in the newer crankshaft from the freezer, still binding, pulled it back out, meticulously cleaned the bearing lands again, back together with a new thicker gasket I made, still binding. Made a a crankshaft puller out of some washers and a wheel nut, and pulled it toward the stator side, which freed it up. Once I had the oil seals back in it seemed to not spin so freely anymore.

I've removed the oil pump shaft, and tank, blocking the hole with the oil pump and blanking the feed line to it, and also removed the started assembly, keeping the motor in place. So pre-mix and kick start only for now.

Unfortunately I still have a similar noise.... possibly it's not quite as bad as before..

I feel like I need to have another pull toward the stator side to free it up a bit more. I also feel like this could've been all I needed to do to the original crankshaft, but too late for that now.

Temps have gone down a bit from where they were at before, so I may have made a positive change.

Main lesson I've learned is, I needed a crankcase puller, as much as I don't want to have to buy one, it would have made the job a lot easier. I was ending up giving it a fair wack with the rubber hammer I have, which is actually too soft for the job. Also the crankshaft puller I made was pretty critical in my case, heating the landings and hitting with the rubber hammer did nothing.

Also learned that when you're using the heatgun or torch it has to get really really hot, not just heated up, hot enough to sizzle water on before the bearings will give way from the lands.

I found this really helpful

www.youtube.com/watch?v=WMg5P98dY9I

and this

www.youtube.com/watch?v=5Nd2q5MP25Q

Will see how it goes for now.

I'll look at getting a full circle crank, decking the Malossi Sport cylinder and rebuilding with the hope I won't have to mess with it for longer.

[aeroxbud]

The proper tools definitely make it an easier job.
Usually you can just centre the crank with a light tap with a soft face mallet. Once you put the seals in it won't spin like before, as the seals are tight enough to keep oil in.

[broyager]

The noise is exactly the same after all that... possibly more consistent now, as in it tracks rpm.

Is it just piston slap in the end? or pinging?

The noise is lighter and thinner when the engine is up to temp, I guess when the oil is thinner?

Sometimes when idling cold the noise goes away for some moments, then returns.

Runs great, as good as it ever has (have the squish sorted - not too tight, and transmission is entirely cleaned etc), doesn't overheat..

Just a quick update, I have;

*Replaced the crank with a 2nd hand lower km crank
*Checked reeds - they are fine / new already
*Checked the bore - looks fine no scratches
*Checked piston - has scraping marks on the skirt facing the exhaust, doesn't look too major
*Replaced small end bearing with a new wider one
*Hand honed the cylinder, fully cleaned piston ring lands and replaced the rings with new ones. Previous rings wore down quickly - Piston is between 1000 - 2000km's old
*Removed everything from the crankshaft to eliminate all sources of noise (no change)
*Pulled starter clutch / gear and oil pump shaft out, and removed the main stand
*Preliminarily tested the Malossi Sport kit - inconclusive, don't really want to run it if the crank is bad

The noise seemed to get markedly worse after the hand hone I did on it to put the new rings in, which won't be broken in yet. I don't think I rounded the port edges after that hand hone. I'll have a look at that on the weekend

I think it's still worth getting a new crank, the original one was only 10,000km old, but I think I am running some pretty high compression, the oil seal on the variator side has been leaking worse and worse since the BBK went on. RPM's never over 9k though.

The Voca crank from speed-line is on sale atm, can anyone advise against the additional 20euro for a machined conrod?

[aeroxbud]

Did you check the ring gap after honing the bore?

[broyager]

Yep, though I can't remember if I measured before or after honing the bore, they were bigger than usual for a fresh set, between 0.011 and 0.013 from memory.

I'll measure them again when I have a look at the port edges.

Did I go too hard on the hone?

[broyager]

Pulled the cylinder, and gave all the ports edges a really good going over.

Measured the ring gaps at 0.015".. so they are wearing really fast. These rings have maybe have 150km's on them at the most?

Still clattering away though, no change in the noise, possibly it's less consistent now, but this could be due to slightly lower compression / bigger squish, and it running richer.

[broyager]

Well, I've been running the Malossi for a few days.

Had a good go over all the port edges, removed some rough casting spots in the transfers and semi polished the exhaust port.

Added some thickness at the base gasket to get the piston crown lined up with the bottom of the exhaust port at BDC.

Running fantastic, has more power than the Naraku, easier to rev, seems to be more refined in delivery, and is a little bit quieter too.

Plug looks perfect with the same jetting as before, using the BPR8HS successfully on this build.

Didn't do anything about decking top of the cylinder, so squish is pretty wide, around 1.5mm... but it doesn't seem to be suffering from it. Running cool (but cool ambient temp here atm 16c or so)

Seems to still make the same clattering / clacking noise, but at a much much lower volume.

So maybe this is normal, time will tell.

Will start saving for a new crank in any case.

[bigmatthew86]

I mill the head a little to get down to 1mm & just run it.

[broyager]

Malossi Sport heading the same way the Naraku did, gotta be the crank, though it's odd that both cranks are doing the same thing (rattling). The original and 2nd hand one from the PMX case were about the same age, around 10k. The 2nd hand one must have been buggered to begin with, or I was too heavy handed on removal / install.

Otherwise runs very strong, plug looks really good, a good dry brown.

I've ordered the new crank and sundries. I'll be treating it very gently when getting it in.. My 2nd go at installing 2nd hand crank went pretty well though, I did it outside and was way more generous with the heatgun. Feeling confident going forward having had the practice.

I hope it holds together in the meantime while the new crank is in transit, should only be a couple of weeks. Have new rings for the Malossi coming too, just in case they are getting worn down by whatever is happening with the crank currently

[aeroxbud]

It doesn't take much of a knock to put a crank out of balance.
Good luck with the new one.

[broyager]

So...

New crankshaft is in, and the noise has not returned. I'm noticing what I can only imagine is the reeds flapping, but nothing coming from the cylinder.

Quite a few adventures along the way though..

First install was with hot bearings onto the frozen crank first, and one of them I messed up, didn't go straight on, and I was rushing / stressed at that point, and ended up hitting it into place. Either the bearing was not up to scratch as it was, or I damaged it getting it onto the crank.

That crank went into the cases ok, but it had play once it was installed.... Managed to get it centered / spinning freely with heat on both sides and by pulling it toward the stator side. I didn't re-check it once it had cooled but it was really hard to turn once the oil seals had gone in.

So it wasn't really running that well, hard to start, not really revving out, and there was that play in it...

Cut my losses and ended up actually getting the correct sized bearings, listed as Piaggio bearings www.scootling.co.nz/onlineshop/bearing-and-seal-set-for-piaggio-gilera-etc.html (SKF plastic caged - BB1B 447205 A) locally in NZ at a better price, once shipping is included, than the ones I got in the crank order from speedline (NTN - SC04A47CS29PX1). Also bought a cheap bearing puller.

Here's the list matching the correct size. Most of the online shops only have a few options listed for PGO, but there are more available often

bearingsize.info/tag.html?t=20x52x12

Pulled it apart again, pulled the NTN bearings off then proceeded to put the new frozen bearings into the hot cases first, then pulled the frozen crank into each side.

This went ok, but I had to fashion a puller... couple of old variators, some wheel nuts and washers... got there in the end... pulling with the nuts only, crank was cold though, and used plenty of freeze spray.

Important to note that plastic cage bearings do NOT take any heat from a heatgun.

Variator side



Stator side




Most time consuming part was getting the woodruff key in.. it didn't fit straight into the new crank, I thought it might be press fit, tried to press it... nightmare, spent an hour or more on that. In the end I filed it gently down to size.

Still had trouble getting it centered, must be a peculiarity with the PGO cases, had to pull it again toward the stator side after heating it, then it spun freely.

Also did some minor port shaping on the cases, I would've regretted it if I hadn't.. shaved some of the bottom curves of the transfers on the cylinder side too, as these were sharper angles than the cases. No other case matching was required. I could've taken a little off the top of the transfers, but I figured the cylinder wasn't blocking any flow there. Gave the exhaust port a better polish too

Case work probably did nothing I realize but had to do it for peace of mind lol....

The PGO cases are pretty good as they are. Worth noting that the older 2nd hand PMX case set I bought were not as good as the Ligero, slight differences, but the transfers were different shapes on each side of the PMX.. real wierd looking, I'll try and find a picture.

After all this though I still had a pretty hard to turn crankshaft after the oil seals went in. The ones I bought were Zoot from Speedline, and the size on them was 38x19x7, and the originals are 38x20x7, details of which aren't on the listings. I contacted them and their tech said the size is correct, and it should be fine as is.

I found some the right size locally again, 38x20x8 (there's 15.5mm of space between the case lip and the bearing on the inside). This went in a but too easy, and was on a slight angle... short story is it popped out when I gave it some beans after I took it out. So I put the 20mm one in and the cut the middle out of the 19mm one which was binding, and pushed that in on top, so there was about 1mm still protruding, but not binding on anything.

Crankshaft doesn't bind as much now, and can idle much more smoothly etc.

Did a bit of research on oils in the hope of leaning it up and getting it running hotter etc.

This chart and page is pretty interesting, indicates that cheaper less synthetic oils should be run on a hotter plug, and at greater mix ratios.



dragonfly75.com/moto/plug

So my tank now has some Full Synthetic Castrol Power1 innit still at about 40:1 though but running well with a new bpr8hs. It can idle much more comfortably at lower RPM now, without it threatening to quit. Could go to an 82 on the main I think, but might mess with ratios a bit first, possibly open up the snorkle on the airbox slightly. Exhaust is the limiting factor but it's a pretty loud exhaust as it is stock, so I figure it has a bit more flow than other standard exhausts.

Squish is still a huge gap, so not running optimal yet. It was running better on a thinner base gasket, which meant the piston wasn't quite at the bottom of the transfers and exhaust port, but squish was tighter and it ran with a lot more power. Will just run it for a while like this, maybe put the thinner base gasket in, but ultimately want to get someone to take 5mm's off the top of the cylinder. There is a big chunk there which basically looks like extra. The head works as it is perfectly with the Naraku cylinder I have as a spare now, so would rather not mess that situation up by taking material off the head.

[broyager]

Here's a shot of the PMX cases, left hand side as like a deep cut, and the right is more medium and similar to the Ligero cases.

Looking closer the oil journals? are different shapes too.... so maybe these are actually from different PGO scooters....



I've just had a look at the snorkel, and the inside end internel dimension was 16mm (15.85mm) which would have matched the original carb. It tapers down from quite open (25mm or so), did some figuring, and cut 10.1mm off the end of it, and now the inner diameter is 17.3mm, matching the Dellorto.

Haven't ridden it yet but seems to have a lot more throttle response.

I am already a bit rich anyway, but richening the idle/air which made it idle better, will see how it goes.

EDIT: Scoot starts properly now, no longer suffocating, goes a lot better, settles back to idle more cleanly and almost back to the power I had before the crank replacement, when I had a tighter squish.

Highly recommend this snorkel mod to match carb size. I have tried previously to run without the snorkel, but that took the inlet up to 27mm or so from memory, which is too much for the stock exhaust.

Once I sort the squish I should be off to the races..

[broyager]

So I did this to the original head, using sandpaper, by hand and electric drill clamped to a table.

Squish band shape looks good, though the outer edge is a bit soft.

Before at 50cc

After at 47mm

Another view

 

I guess whatever is doing the gasket (copper spray here) is going to be pretty crucial, without that definitive edge to the 'end' of the combustion chamber.

I need to tidy up the inner of the combustion chamber as it has some pitting etc, but might chuck it on to see.

Seems about right, with the combustion chamber being smaller than most though, so will raise compression I think.

Can anyone see any serious side affects? I imagine some small amount of mixture is going to get caught in the small gap that has been created by the softness of that curve at the 47mm mark.