Modern Vespa

So, last year my GTS was making an irregular tinkling sound, that we discussed here. After an unrelated head gasket replacement and reassembly, it changed a bit, but still around. I'd gone back in and checked the clutch...again, reassembled and parked it for the winter. Noise is gone...I'm not going to ask why....

But, after my first serious ride of perhaps 10 miles or so, I was listening to the engine and it seemed to be noisier...but then again I've gotten paranoid about noises. So, wondering if I'm just being neurotic or there's a potential issue. FWIW, scooter's running well, no performance issues at all. It's been a pretty weird time, tracking down elusive noises....

Any thoughts?
https://youtube.com/shorts/ehJh3r8eyBQ?feature=share

I had two customers with weird Vespa noises this week.

One was a license plate vibrating awkwardly, solved by taking the license cover off.

One was the clip from either a cargo net or a bike cover had come off from the cover and the clip was still stuck around a crash guard.

Both were making the Vespa make very weird noises.

Fingers crossed it's just some stupid little thing like that.

Does the noise go away with higher revs? I would say that leans towards piston slap. Couldnt tell from the blip of the throttle.

Does it favor one side of the engine or the other? Water pump side vs. timing chain side? Do you feel comfortable that you adjusted the valves correctly after the head gasket swap?

IIRC, it presists at higher revs...at least it sounded similar at 30-40 mph.

I can see if I can isolate the sound tomorrow...

As for the valves, I thinks...I think I rechecked them several times.

Well, rode in to work today, sound seemed perhaps a bit quieter but the rattly sound from last year decided to re-emerge. FML I'd made peace with that sound already as I've decided it's not ominous......

Definitely doesn't reduce with higher revs, actually gets quieter with idle only.

If anything, it's louder on the water pump side.

Does any of that clarify?

I had a similar sound, a bit less metal sounding and only while on the center stand, needed to loosen the 8mm bolt on the RT (water pump side) of the inner plastic rear fender and push the fender up and retighten the bolt as the fender was clicking against the metal engine housing

That doesn't sound right to me. I started my GT200 up and it doesn't sound like that. That sounds like a knock. But the engine being down in there surrounded by the metal frame can amplify sounds and create echos. You said it was unrelated, but why did the head gasket need to be replaced?

I had a coolant leak, and seemed the pretty clear culprit.

The noise last year was more of an irregular rattle...and preceeded the leak by a month or longer.

You're right about the body, it doesn't help locating sounds...

That's an unexpected, but easy fix! After having just reassembled everything with the head gasket I shouldn't have anything loose. I think.

Have you tried listening with a screwdriver/chopstick?

This is a very steady, even noise. It's not a rattle or vibration. It's speed increases with engine speed. It is definitely coming from something in the engine or drivetrain. I don't believe it is valve noise. Loose valves would make more of a clicking/tapping sound. This is a deeper, lower pitched noise, like something heavier moving up and down/back and forth. It's a reciprocating sound. Sounds more like a rod knock. I hope that isn't what it is. Does the Quasar engine have any kind of balancer in it? I had a motorcycle engine make a similar sound, turned out a rubber damper in the balancer assembly had failed. Also, is there a possibility of an exhaust leak somewhere near the head?

Not this round...did it for last years' noise. I'm still a bit green at listening that way..or maybe worried about getting the chopstick stuck in my ear, lol.

Kind of my worst fear. If you were with my thread last year, you'll know that I'd run low on oil a couple of times (lost dipstick....felt like one ) so damage from low lubrication is a likely problem...though I had a good run, maybe 6K miles of good running after the fact, but I assumed at that time I'd probably shortened the life of the engine.

I'll have to check the exhaust header, just in case. No need to avoid the easy stuff.

If it is internal, the question to ask myself is do I feel up to an engine rebuild? I don't have regrets from last years' work, and it's going to be a heck of a lot easier pulling the engine....all the stuff i wound up redoing, the head-scratching, and the dirt/grease isn't an issue. I just need to be sure that I'm doing what I need to do. Would have been nice to know this was just lurking around the corner last year, I could have saved some work...though guessing there's no way to tell other than pulling it all apart to check... (?)

I had an idea for doing another sound recording seeing its a nice day....stay tuned. And thanks for the input so far!

What happens if you take off the belt and run it? That would isolate it to engine or running gear?

Umm, its been done before, but I've been told by those I respect that one should never, never do so. So, no.

Here's the latest attempt at giving more info....may not help much, but it gives more of an"on the road" version. Sorry about the view....I'd rather have nothing but people have freaked out at clicking on sound links...

It is ok to start it up and idle it without the belt. I even recommend trying that before pulling and disassembling the engine. Leave the front pulley in place. I wouldn't rev it too much without a load on it, that even includes revving it on the centerstand. There is no load on the rear wheel.

I did try that for my sound last year..no problem, but didn't help localize. This sound doesn't localize toward the drive side like last year's, in fact, just slightly louder on the right.....

So you were told by "others that you respect" that you should never run your scooter with the belt off but you did and there was no detrimental results, even though it didn't solve your engine/drive issue on another occasion? What am I not getting here? Besides, if the rear wheel is off the ground there is virtually no load on the engine, it can't take more than a very small amount of torque to spin the drive train with no load. What is the difference? Is there some factory publication that says this is not permitted?

Okay, perhaps with the belt on and the cover off?
Either way, the answer is beyond my pay scale.

Some people have done it and got away with it, but it doesn't do the clutch or the driven shaft inner axle bearing any good whatsoever. And if you forget to put a washer and nut on the end of the driven shaft to hold the bell in place, stay well away from the left side of the scooter when you start the engine...

Running the engine with the belt off is also not advised as there's nothing to push the variator back against the rollers, which can then tip over and cause significant damage.

Thanks, Jim. As long as this is dissected, how about with the variator removed?
(not arguing for doing it, rather to be sure I've got the right reasoning).

I see the "run it without the cover/variator" camp has joined the chat.

enjoy whatever damage-- mechanical or personal is brought by doing that incredibly moronic act.

I'll see myself out now, thanks.

Don't let the flying clutch bell hit your arse on the way out.

It can also damage other bits just inside the crankcase I gather, but I know not the details.

I never suggested running it without the cover but I see even on this very accepting Vespa board there are unpleasant people. Maybe all of you of that ilk should make yourselves known now all at once so I can decide if this place is a place I want to contribute too?

^^ time for a chill pill

I have had the same thoughts as you with a few of the unpleasant people on this site. I suggest you stick around awhile as the many more pleasant people could make the unpleasantness somewhat tolerable. I sure appreciate those that are here to pass on their knowledge and how riding can bring a smile to your face on the most unpleasant days.

Thank you Frank. I'm still excited with my scoot so that sustains me!

Running the engine with the belt removed will have no effect on the clutch, or any part of the final drive, as none of it will still be connected to the engine. The clutch does not come into play at all here. You could remove the rollers if you are worried about them. The only thing to be concerned about is over revving the engine with no load on it. I have run car engines on an engine stand with no transmission connected to them. I have run motorcycle engines with the drive chain removed. Doesn't hurt a thing. Just don't try to rev them to redline. OTOH, if you're pretty sure that is not where the noise is coming from, and I can't think of anything in the CVT that would make such a noise, then I guess there is no point.

That's pretty much where I'm at. I've listened at the transmission case (screwdriver/stethescope) and got nothing....it anything, it's the quietest part of the unit).

There seems to be a relationship between the pinion that drives the oil pump and the variator assembly . It doesn't look to be keyed to the crankshaft and it might be pinched in place on the crank like the variator boss. Without the variator bits in place and torqued down, you may not have positive crank drive to the oil pump.

the timing gear is keyed, the crank is pinned. the pump gear is floating. without the variator in place all of that is free to just go on walkabout.

Good to know. I have a Quasar 250 with a locked-up big end that I want to resurrect soon. Hard to tell what's behind the seal/cover without getting one of those fancy tools.

hit me up on the tech line, I'll gladly lend you mine when you're ready to tackle it! removing that without the tool is an exercise in creativity and frustration. the tool makes the R&R a breeze.

@ fledermaus. First off, disclaimer: I don't own any Piaggio products. I'm thinking out loud here and throwing out a few ideas. It may bad advice, but hey it's free!

The first thing that came to mind was cam chain tension or worn/broken chain guides. That was until you mentioned the noise seemed more prevalent on the other side of the engine...

When was the last time the valve adjustments were checked, how many miles on the engine?

Then there was mention of the engine being run low on oil last year. Using a clean oil drain pan, drain the engine oil, then insert a larger funnel into another waste oil jug. Line the funnel with some material like cheese cloth or something that will allow oil to pass through and catch finer debris. Then pour the drain pan oil through it. Also cut the oil filter open and see what the element looks like inside. If the bottom end is making metal, it should show some evidence in the cheese cloth and filter element. It's an inexpensive and easy check before going in deeper. Good luck.

Hey, Bearcat, I like your approach....at minimum you don't step on any toes!

Okay, they low oil episodes actually happened several years ago...maybe far back as 2018. It's run fine since that, maybe 8K miles. There's a filter in the oil drain on Vespas which should catch metal bits, and in several oil subsequent changes never notice any.

Guessing you missed the drama last year when I replaced a leaking head gasket...valves were checked when buttoning everything up, probably less than a hundred or two miles since then. Cam chain tension is a new one to consider. I know nothing about cam chains other than their function...nothing about troubleshooting them.

I missed the entire previous history part!

From a quick search it looks like the automatic cam chain tensioners are not really an issue, that is with any appreciable failure history. I was just pondering that the ratcheting mechanism/teeth might be wearing and not holding in a certain area of travel. This may cause that rotational sound as the chain is running looser and ticking against the guides. Who knows? If it jumps timing that could cause some major damage.

Perhaps backtrack the valve adjust maintenance that was previously done. Maybe the lock nut on the valve tappet adjustment has backed off. That would be catastrophic if the nut came off. I'd double check the valve clearance.

The metal body can really amplify the noise. I'm just putting a few ideas out to try and help isolate the problem. Other than what others have already posted, I'm out of ideas.

Sounds reasonable. Once I decide to go for it, that's probably top of my list...it's a bit of a project checking valves, but it's the same work preparing to pull the engine anyway.

Despite it edging into the riding season, it's as good as it gets for wrenching now....garage is a comfortable temperature, tends to be rainy/windy too, and with luck have it out on the road in some weeks.....assuming all goes well, of course.