Modern Vespa

You where actually correct in that turning the engine CCW will put the slack in the correct position, tensioner side. The spring loaded tensioner will then take up the slack and being it is ratcheted will lock in position. I just didn't want you to turn the crank without the timing gear set and move the timing mark position.

Optimistically, you're past the half point on disassembly. Hopefully it will be solved with the head and cylinder removal and there will be no need to go deeper.

No, no, no—gotchya as in I get what you're saying. I should have added a big thumbs up 👍.
All good Fledermaus

No problem....Yeah, I mistook it for a little friendly poke, but no harm, no foul.
We need more emojis!!!

I put a lot of miles on one that was off one tooth. It didn't have any power, but no noise to show something was off. You can't use the mark on the water pump to set TDC on the GT, you have to use the one on the stator. Same with the GTS.

Sp, which is the one behind the black nylon cap?

I meant flywheel. It's been a long week getting caught back up after two glorious weeks of riding as fast as a small displacement scooter can through spectacular landscapes. There is a firing mark and a TDC mark, and on the GT200, the one you don't want to use is the one visible through the waterpump.
I would have to look at a service manual for the GTS to tell you which one is correct for that model.

man, that's wild! the two I've seen one was just a no start and the other had juuusssttt kissed the valves enough to touch them up.

that's the flywheel mark, it matches with the indicator on the pump housing which corresponds to the 4V mark on the cam timing gear and the tick mark on head.

the issue doesn't exist on GTS (quasar) motors, only the 125/200 LC leader motor. and even on those it doesn't exist on all of them.

basically not a concern for you. adhere to the FSM

The manual says to use both but I think the flywheel mark is just to confirm you're using the correct 4V arrow. Should look like so

It looks so good there....less so when you're reaching around with a wrench to turn the engine over while aiming a flashlight....

Anyway, I'm all good with the where and what's of timing....unfortunately I guess that will all be undone as I start tearing the engine down....

Or fixed!

Okay, a few minutes out in the shop this morning. Brief thoughts about adjusting valves and putting it together, but really wanted to put my mind at peace and have a look at things.

Glad I did. There was some light galling on the cams and lifters last year and I expected same. I was a bit shocked to see how much worse it looks, and I'm not sure why. Not many miles since I replaced the head gasket, I used assembly lube, etc, so I'm flummoxed.

Clearly I need to replace some parts. I'm curious if the wear would be affecting the valve clearances? Doesn't change anything, but was surprised to be so far off from all the pains I took to get it right.

Wow, yes, that will definitely alter the valve clearance and is most likely the cause of the noise.
It will change a lot more than just clearance, lift, duration, overlap, timing. Not sure if you need to even pull the head at this point. Those with more Vespa experience will let you know.

You're using Judy-approved rotella aren't you?

Thanks for the input!

I think greasy had concerns over the bottom end, we'll see about his thoughts at this point.

Would be nice to understand how it could sustain that much wear in so little time. My auto mechanic friend and I think the hive mind here thought the wear was minimal enough to reassemble last year....I doubt anyone could be of that opinion now. Had a bit of a problem getting a good representation on the photo.

I'm next due to pull the cylinder...if so, and I'm going all the way, any reason to leave the piston in the cylinder? Is it still important to maintain TDC? Obviously want to get my eyes on the barrel...Is it fair to assume that visuals is enough to judge whether piston slap is occurring?

Is there really any other oil?

And in case anyone ventures to ask, yes, I DID put oil in before starting it!

I don't know the composition of your cam, treated (hard faced) once they start to wear they will take off and the wear is accelerated. Funny thing is some camshafts are made of plastic, not run of the mill plastic but plastic.

TDC is not import at this point. You can pull the cylinder then remove the piston, rags around the studs so you don't damage the piston or pull the cylinder up until the piston pin is exposed and remove, you can then remove cylinder/piston as one. Is one better than the other, individual choice.

well.... at least that's something definitive.

when we first ran this through, I had mild reservations about the wear exhibited on the cam but the rockers looked clean, so I said to ship it. which is what I would've done on my own bike, or on a client's ride with the caveat that something like this could might maybe happen.

accelerated wear is always a tricky one in that there's not really an absolute way of predicting when or how it will happen. for instance, this may have been the exact same outcome had you not been in there previously. I've seen stuff wayyy worse that your initial findings run along fine for ages and to counter that I've see stuff that looked immaculate go brown and round for no good reason.

anyhow, seeing as your oil was glitter free and the discovery of this makes me breathe a little easier on what the condition of the bottom end may be. you're this far in, so I'd say keep trucking and yank the barrel to do a base gasket. you'll be able to ascertain any piston slap and check the crank for slop at that point too.

throughly inspect the valve tips and make sure they do not exhibit any undue wear characteristics, the FSM gives the spec, but you can usually just give it the calibrated eyeball test and know if you're in the clear.

Thanks for the input greasy!

Two questions...Leave the cylinder in the barrel for now, or just pull it apart fully.?

And, as you're saying it, I can check the crank bearing without splitting the case? That seems like good news...

So, one of the concerns was piston slap.

Been checking the barrel trying not to dislodge the rings atm, though have only a cluehow far up the piston they are. For what I know, normal appearance is slight swirling marks, whereas slap causes a more longitudinal wear? Not the easiest for photos, but here goes.

I believe piston slap would be shown at the bottom of the barrel.

Ah, that helps. I'm just exercising caution and trying not to emulate a chimp with a wrench.

On re-read, I guess that answers my question. I know rings can be a bit fiddly, but messed with some 40+ years ago and don't have PTSD so...

Valve tips look flat, without scoring, so good to go there? Can do a photo if it helps..

You're so close to finding out! Even the o-rings are ready to go. I will say that, in the pic of your cam, the one lobe looked really messed up like it had a flat spot. But I'm guessing (from having photographed mine) that's a weird lighting effect.

That's because it is! As you know, getting a decent photo isn't easy. I've taken some that don't show what I'm seeing in real life.

BTW, those O-rings are on their way to the trash, lol. I've yet to get replacement, waiting to see what I'll nee...with any luck, get it in one order.

A suggestion, when installing the new O rings over the studs put a piece of heat shrink over the threads and shrink, lube and install the rings. It will keep the threads from cutting the new O rings. Cut the heat shrink off when done.

Okay, procrastinated a bit ( kinda hoping for guidance on a couple of questions)... but finally decided to pull the cylinder and leave the piston connected.Definitely some wear on the top and bottom of the piston. I'm not seeing comparable wear on the cylinder walls. Guessing hardness of materials makes the difference.

Soo, guys, thoughts? Proceeding from here?

Concerns over the bottom end. Greasy thought the lack of metal bits in the oil was a good thing. Can it be assessed without further tear down? There's no longitudinal play discernible, but definite lateral play. I have no idea what's normal, so have to call in the pros....

I'm not seeing anything scary.
At least nowhere near as scary as that cam lobe and rocker arm.

Not sure if I needed to pull the piston entirely, but what do I know.

Update on the bottom bearing....there's no push/pull play, lateral play as already stated, but if I grip it with my fingers I can get play up and down (perpendicular to the connecting rod). Kind of a squishy movement if that makes any sense....

I have to wonder if that 'squishy' movement is somehow caused by the crank very slightly rotating. In other words, not a problem.

Looks fine. Try the conrod for any vertical play. Clean everything up, new same thickness base gasket and close it up...

What do you mean by bottom bearing here, and where is the play?

I don't think the connecting rod should move vertically away from the crankshaft at all. I'd look at it carefully if that's what you meant about play "perpendicular to the connecting rod".

I think your top photo of the piston skirt looks a little crappy. Other photo of the piston skirt not so bad. Only one pic of the cylinder. Top pic skirt is matte and can see what appears to be scratches running top to bottom.
Looks to me that it was lacking oil at one point, cam lobe is also wiped I'd look long and hard before making a decision (they say third time is a charm but I'd rather not see you get there, we do it nice cuz we do it twice would be better).

Connecting rod to crankshaft.

I can't discern any motion in the direction of normal movement, i.e. push-pull.

There is lateral movement along the axis of the crankshaft, which I expect is normal. Pushing up toward the ceiling and down towards the floor seems to show some movement. I'll probably go out and play with it some more to be sure, but that's how it looks/feels at the moment.

Yep..- mentioned earlier...

^^^ this.

I don't see any cause for concern on the barrel and piston.

on the crank, there should be some lateral play, and virtually no up and down play. basically, get ahold of the flywheel and grab the con rod and see if it's all loosey-goosey. there should be no perceptible give.

I'm not sure how one evaluates a cylinder bore with a partial picture but stranger things have happened. The thing is piston slap indicators favor one side of the bore as well as the piston. The only way to be sure is at minimum full pictures of the bore and piston (I'm using an iPad and can enlarge your piston pictures and the top one doesn't appear to be pristine but it could be lighting, shadows, reflection). If you really want to know if they are in spec. measure them, the service manual will give you a service limit. Ask three people the same questions and you might get three different answers. I searched and found you post on the head gasket replacement. I would have never reused the cam and rocker, I also would never remove a head on this type engine and not replace the base gasket, that gasket will yield under torque and not come back when the bolts were unloosened.

Finally the engine was running on a milkshake, water is not a good lubricant and there is a possibility that the oil pump suffered. Something I would check at a minimum but most likely replace. Everything you repaired could be for not if the oil pump if not up to par or fails. Overhead cam wear generally starts from lack of oil on cold start and progresses from there (all other causes being in spec) Some OH cams are designed to sit in an oil bath when the engine is off, this engine is not.
As always hoping for the best.

Well then, here ya go! Seems like only minor striations to me.

BTW, photos are sideways, top/bottom on left.

So essentially the check is simply push/pull on the connecting rod. I'd expect a bit of a clear "clunk" feel if it's off?

Edit: If it's going back together, it's parts time. Besides the obviously worn stuff, anything else to replace such as hoses? It's a 2015..... they're not showing cracks, etc....

Is that a Nikasil coating in the bore?
The intake side is not as crisp and well defined, as the exhaust side (where the black ends). It also appears to be dragging down and matches the piston skirt intake side which I thought was a little ratty.
The cross hatching looks good though. That is what the result of piston slap can look like, a runway down the bore. Usually more pronounced but it just doesn't look right to me. If you're fine with it, put it back together. I'll step away.