Modern Vespa

Are you measuring it up and down or left and right?

This answers your question.
They're giving you the standard length but the service length would be better. .5 mm would allow for measurement accuracy. If the plunger is smooth with no issues, move forward.

Both the right way and upside down for Southern Hemisphere correction.

So, after a 6 week (according to MV) hiatus, I'm back, and at reassembly stage.

Warmed up with replacing the speedometer cable and shock on my LX150, though somehow my battery that I purchased a bit over a year ago died somehow...kept it on intermittent tender over the winter, rode it on and off this year....anyway, I hope that's easy enough with a replacement....

So onward! Installed new oil pump and put that end of things back together, starting at the piston next. Fingers crossed that this doesn't take nearly as long as getting it apart did. Better weather for shop work coming, which should help.

Okay, hit my first speed-up. Pulled out what should be the base gasket, and took a few minutes to sort out the orientation and slipping it over the piston, but the fit looks far from right. Either my brain isn't working right or there's a fitment issue. Got back on the website and I indeed got the right set. Thought it needed a flip, but that doesn't improve things.

Guess I could contact SIP to see what's up, if they could have made a mistake, but hopefully someone here can help...

BTW, Insult to injury I threw TWO sets into my shopping cart, so I even have a spare.

Silver lining your SIP order actually arrived.

The former.
That's not a base gasket.

Yeah. Box was kind of beat up and went looking for my replacement mirror first, lol.

Hmm. Hint as to what it is?

I'm thinking I may not be done shopping....

There's only two options.

I think I should have stayed out of the hot garage today..my brain apparently isn't processing reassembly all that well (I've been in salsa and tomato canning mode half the day). I managed to bust a piston ring to boot trying to get the wrong gasket in place. If there's any consolation, the right one goes on much easier.

Just did a Scooterpartsco order this morning, of course. There's always something I miss after I click the button.....

Okay, its way too late to be dealing with this, but just had to make a trip out to the garage....yeah, it's all pretty clear now. Sheesh. Well, at least I'll sleep a bit better.

You don't need any of these:
https://scooterpartsco.com/gts-300-engine-c-3637_3643_3804/head-gasket-for-vespa-gts-and-gtv-300-p-8906.html

but you might need one of these:
https://scooterpartsco.com/gts-300-engine-c-3637_3643_3804/cylinder-base-gasket-06mm-p-9266.html

Thanks..I'm good on those, but you'll be hearing from me on some other bits.

Does it fit where you were trying to put the head gasket?
I've done projects where there were a year or more between attempts to put something back together, and a lot gets forgotten in that time. I have found is that the parts will fit back together like they should most of the time, if they are correct, and the parts manual will usually (It's a Piaggio, so not always) show the correct assembly order of the parts. If things don't want to go back together, or don't look right, it's usually because I've done something wrong.

Glad it's not just me. I seem to have a predictable pattern of forgetting to take notes, photos or both at critical juncture, and even in a matter of a couple of weeks the memory gets fuzzy and what seemed to be a no-brainer on disassembly is now a process replete with uncertainties.

Anyway, it's all pretty clear, at least until I get to the next stumbling point. What I need to learn is that when I'm tired, overstressed and things aren't going well to walk away for a while to get a fresh look at things instead of trying to push through....

Okay, got the rings on the piston....mostly, starting to fiddle with getting the cylinder on....but...

As noted above, using new rings as I snapped the bottom one messing around with the wrong gasket. Ordered a new set (I assumed they didn't come individually....but they did, at least individually wrapped) and replacing all of them. Got the lowest two seated, but the top, L-shaped one has me a bit befuddled. Thought I'd noted the correct position of the old one, then watched Robot's video, and now I'm confused. Robot states the flat part of the ring points to the crown of the piston, but the cylinder has a deeper grove toward the bottom of the piston, and if the ring is going to compress enough, I think the L shaped part has to be oriented towards the crown. Robot can't possibly have it wrong though. Maybe I need a mental health break?

The service manual has a vague description of - "Install the first compression lining in the direction imposed by the housing." That would imply matching the stepped groove in the piston, no?

Correct orientation is how your old one was too. It's a Dykes type ring and orientation is standard…

This is from Piaggio's manual. You also have to rotate the gaps to 120° between each other…

Thanks for your response! I'd looked at the manual already, but the drawing doesn't enlarge well and maybe it's my cataracts, but couldn't come to a conclusion on that.

It looks to me that the piston and ring have matching outlines and should fit accordingly? It also seems the ring's not going to compress enough otherwise....

While I'm pondering life, I'm wondering if trying to fit the cylinder onto the piston that's already on the connecting rod is a fools errand or not. Also thinking a ring compressor seems pretty desirable at the moment....

One, East, second eventually, then taking on the third lost the first two, now struggling with the second.

ARGHHH! I hate rings!

Any hacks?

Woo-hoo! Finally got it, no blood or nuttin'!

Definitely fiddly, but a sweet feeling when it's together. Did take better part of the day, but considering I messed with the dishwasher, made pita bread and minestrone, it wasn't all bad. If it had gone smoothly I'd likely have stuck with the project, but I'm satisfied for now. From here on is familiar territory, which should help a bunch.

Mmmm....
Bloodless pita bread.

Was going to joke about kneading bread helping to clean shop hands, but I DID wash well, and besides, you lot would believe me, so no risking that.

Wife did think the pitas were delicious, so who knows?

Progress!

So, engine's in!

Connecting various bits...Freaked out for a minute as I'd forgotten to stuff something in the intake port, noticed when the cap for the bleed screw went missing. Logical to think it toppled into the hole.

5 minutes later, I found it on the lift.

Bit challenging sorting out the electrical connections, a few hiding under other hoses, but think I have them all. Only one to locate... Edit: Ah, the exhaust manifold connection! No wonder there's no mate for it right now.

Well, we can't stay drama-free for long, it seems. Putting on the throttle body, I got resistance from one of the bolts....and now I'm wondering if it wasn't aligned right and starting to get cross-threaded. I know plowing ahead and trying to force things is only going to make a mess by stripping the threads, but I'm not sure how to procede....is there a way to rescue it? I do have a tap set, threads match the bolt but strangely it doesn't screw into one of the other good holes....."

pull it all back and have a look see. if it's not too garbled, maybe gingerly try and run a bolt or screw in there by hand with a little lube and see if it'll clean up the threads.

if no dice, you can try a cheater: get a bolt/screw (same thread & pitch, obviously) and grind a little chamfer on the end see if you can thread that in. kind of a "poor man's tap", if you will.

also, where's the bell for your decompression assembly?

If I didn't have to look for parts, tools and fasteners I'd be a really fast mechanic

Thanks! I may be beyond the first approach ( though didn't try lube). Have a spare bolt, so can have at that.

Don't recall having a decompression bell...doesn't that vary between models? IIRC, gitder's '07 had one... My inventory of loose parts is dwindling so something like that should stand out...

Ha! I hear you.

Haven't had time to work on the scooter...real work, and all, but still seem to have plenty of time to obsess about my stuck bolt.

Greasy, have any details on grinding the sacrificial bolt? Just kind of a shallow chamfer? Quarter inch, maybe?

If that fails....next step? I do have a tap, but just (gently) playing with that it doesn't seem to enter good holes too easily. Just reading about thread chasers, wondering about those....

And finally, what's the nuclear option? Is a helicoil potentially on the menu?

I'll be farting around with it tonight. I want to take it slowly to hopefully not dig a deeper hole.

I think what might have got me started wrong might have been using a wobble extension (which Robot had recommended for one of the other less accessible bolts), allowing the bolt to tip a bit. That and trying to squeeze my big mitts into a tight space....

You ran the bad bolt through a die, and it went through alright. But then you put that cleaned up bolt in a known good hole and it wouldn't go in? This seems strange.

Does a good bolt pass easily through the same die? Does it bind up in the "bad" hole?

Just trying to understand if the problem is with the bolt, the hole, or both. But cleaning up the bolt threads should be pretty reliable, so I'm not clear why that part wouldn't at least fix the bolt and let it work again in a different "good" hole.

Bolt is perfectly fine...as it should be, being steel. The hole, being aluminum, well, that's slightly buggered, it seems. FWIW, didn't do anything to the bolt.

I must have misunderstood. I thought you said the bolt would not screw into one of the other (good) holes either.

Rereading, I understand now that the tap (which you are sure is the right size) won't go into the bad hole, and also won't easily go into a good hole.

Yes, now you've got it! I'm hesitant to have a go with the tap, almost certain it's the right size, just trying it by hand, but it catches early. Just an experiment. I'll trust greasy's suggestion more than my spitballing.

If it's only cross threaded by a turn or two, it may be impossible to get either a bolt or a tap started straight. In such case, I'd be thinking about drilling out the first thread at least slightly oversize, and try again. By hand, only. Also, using a hooked pick to remove any loose material, or MAYBE there's an SAE size slightly smaller but of very similar pitch that you could get in there 3-4 turns and somewhat forcefully wiggle back and forth to get the aluminum back where it should be.

Take off the rubber bits either end and see if it will go in if unimpeded by them?

Rubber bits?


Messing around with it tonight, it seems I can get a good, easy turn or two on the bolt before it suddenly gets very difficult to turn. From the way I'm seeing it, MadisonSully might have the better approach (with drilling), as anything I screw down there will likely follow the wrong threading and just make it worse?

Problem is that there isn't a ton of threading there, so the purchase of the bolt is diminished and more prone to stripping altogether unless one is very careful tightening....

In the meantime I've dealt with the stress/frustration of all that by putting other bits in place....

what? this isn't running yet?

you're behind book time, chief! gonna have to come in tomorrow and wrap up!

Tomorrow?
Pfff, the night is young!

hey, I might be old and washed but the night's a puppy! I'm just getting cooking!