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!Vespa .. trying to make this thing work!

Apr 23, 2020
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Cedar Park, Texas, USA
Some of you may have followed this saga on various other threads, but I'm starting a new one.

Quick history:
After I got hooked on scooters a couple of years ago and mrs72 commandeered my scooter, I got one of my own. I picked an oddball scooter quite on purpose, a "Genuine Stella Automatic". These scooters are a result of a weird history between Piaggio/Vespa, an Indian manufacturer called LML, and Genuine Scooter Company who really only import and re-brand Asian scooters for the US market. Without going into all of that, suffice to say a Stella Automatic is a mildly modernized Vespa PX with a significantly more modern 4-stroke 125cc engine and CVT in place of the old Vespa's 2-stroke/manual setup. LML, the manufacturer, went out of business in 2019, so this rare scooter is basically orphaned in terms of support.

My first Stellauto ran fine and was a lot of fun for the short time until it nuked its starter ring gear and some nice gentleman in Oklahoma gave me a nearly new one that had been sitting for 8 years to replace it. Now I have my second '14 Stellauto and after bringing it back to life, I rode it for most of a year trouble free until parking it mostly at the end of 2022, when it wouldn't come back from winter this past spring. It's been mostly unridden since early spring.

The problems I recently dealt with are boring and you can look at them in the other threads if you really care, but finally with a freshly cleaned tank and cleaned carb and new pulley in place, the scooter starts reliably now and I've been riding it daily for a few days now. But it has some kind of running problem that I am hoping to sort out in public view on this thread.

The issue is inconsistent running under load at higher rpms. Ever since I got this with 38 miles on it, it has had the same range of issues. Hunting and inconsistent idle, surging while under cruise, and generally iffy running. Now it has gotten to where it really just won't rev above about 5-6k rpm under load and that means a max speed of about 40mph. And if it sits idling like at a long stop light, it nearly stalls under rough idle conditions and then really doesn't want to go when it's time to move.

My current theory is that most of these oddball problems are due to the Dellorto "ECS", or "Electronic Carburetor System". It's a half measure between EFI and carbs, with the intent of meeting Euro smog regs without having to actually do EFI. Essentially it's a carb fitted with a throttle position sensor, an O2 sensor in the exhaust, a little air solenoid valve that meters extra air into the carb to lean it out, and an ECU to control it all. The ECU takes input from the crank to calculate RPM and has a mapping not unlike EFI systems to provide a mapped mixture across throttle/rpm range. It supposedly uses the O2 sensor input at idle. It's a black box that cannot be tuned. Oh, it also serves as the ignition controller/ignitor, and is rumored to do some ignition timing, but there is no kind of knock sensor so it's not interactive. I am guessing just a static advance map based on throttle and rpm.

While I was using the scooter regularly before all of the recent problems, I had disabled part of this ECS by removing the air solenoid hose and plugging the port on the carb, so the carb would just run max enrichment according to the jetting. Looking at the spark plug makes it clear that it was running very rich all the time, which I guess is to be expected. When I did the recent repairs, I hooked the air solenoid back up, and now it has these weird running issues again.

This 24mm Dellorto ECS carb is unique to this particular scooter and like one or two other Peugeot scooters only sold in Europe. Dellorto doesn't list it in their parts catalog. LML didn't even put it on any of their other 4T engines. It's very difficult to find parts for this carb, and tuning information is nonexistent. But there are jillions of GY6 scooters, pocket bikes, go-carts, you name it, all over the world, which all use 24mm Keihin PD24J carbs or clones of those carbs. So my next move is going to be trying one of these PD24J carbs in place of the ECS carb.

The PD24J is slightly larger overall than the Dellorto, and the Dellorto carb currently touches the fuel tank on one side when fitted, so there's a chance I may have to fab up another intake tube with a bend in it to scoot the bigger carb over a little bit to clear the fuel tank. Also, the stock airbox has a curved rubber hose that connects to the carb which is not going to fit pretty much any way we slice it, especially if I have to scoot the carb over. I may have to come up with some other solution, including ditching the airbox entirely, which I really don't want to do. I think I can likely make the throttle cable work, perhaps having to trim some of the housing. The big thing is that the Keihin carb has no way to use a throttle position sensor, so either I have to rig something with some kind of linkage or just do without it. I have ridden the scooter before with the TPS disconnected (inadvertently) and it seems to run fine this way, so besides putting up with a flashing ECS light (kind of like a check engine light), it might work ok.

The goal of fitting an easy to service, abundant-parts and current production carb has enough benefits to make this fab and tinkering exercise worthwhile. I also ordered a jetting kit, but I figure the stock jetting for a typical 125cc GY6 is probably a good enough start. If I wind up going the no-airbox route and using a cone filter, then popping the carb off to rejet is a cinch.

This weekend I plan to do this swapping, in hopes to get the Stellauto running like she should so I can ride with mrs72 on her new(ish) Kymco scooter for the whole of the fall. While I'm goofing with it, if I can find the appropriate piece of exhaust tubing to make a patch, I may cut out the little catalytic converter and bypass it. I actually think it may be clogged, probably from me running it too rich for too long, and maybe that's half of the running problems.
Alright. This morning I pulled the carb with the intent of trying to make the keihin carb work. Unfortunately the throttle linkage on the keihin cannot fit because the fuel tank is in the way. So I'd need to fab an intake manifold with a bend in it. Also looks like the pod filter won't fit either so I'd need to mod the airbox with a custom outlet hose to connect to the carb. Ok. Somi wasn't down for that today.

Instead I did a more thorough cleaning of the dellorto carb and plugged the air solenoid port. FYI when putting the Dellorto carb side by side with the Keihin CVK PD24J clone, it's clear that the Dellorto is essentially a copy of the Keihin CVK design. In fact, that little air inlet that's used for the mixture adjustment, which I suspected was kind of like a controlled vacuum leak, is actually just a little tube pressed in where the CVK's carb would have a vacuum diaphragm cover and port on a normal CVK.

When I put it all back, the scooter runs really well except one thing. If it idles a long time, like at a long stop light, then it hesitates when you take off and runs bad for a few minutes. Eventually it will return to normal after like 5-10 more minutes of riding. My theory is maybe the float level is too high and it lets the fuel level get too high when idling, then it's really rich until it can burn fuel faster than the fuel pump can supply it. OTOH it could be just the opposite: maybe at idle the fuel pump can't pump enough fuel and the goofy little reservoir is getting emptied and by the time I take off again the carb is low of fuel and takes a bit at higher revs for the fuel pump to catch up. I'm truly stumped on this problem. Any advice here?

In other news, it also can be hard to start when it's hot and it has a kind of rough idle. And if I let it get well and truly warmed up, it will occasionally stall when coming to a stop, which then makes the hard-starting-when-hot problem become really annoying. I suppose this could be pilot mixture, or low float level causing this. The scooter has a 2-gallon fuel tank and I filled it up just a couple of days ago, rode probably 100 miles since then, and it's down to about 1/4 of a tank. Manufacturer suggests it should get 85mpg, but it sure feels a lot more like it's in the 60s. Since I fill it with treated gas at home, it's very difficult to measure mpg accurately. But this would support my theory of the float level being too high, maybe it's just running super rich.

I kind of wonder if the little catalytic converter is clogged, which would make sense if I have been running it super-rich for very long. Once I can find a piece of 1-1/4" OD exhaust tubing, I plan to cut the cat out and bypass it. If I can find a muffler with the right dimensions, I might just cut the whole giant muffler off at the cat inlet and put an aftermarket pipe on it. It's not like this massive muffler makes it very quiet, and if it is running rich due to elimination of the mixture-adjusting port, maybe a free-flowing exhaust would help lean it out.

Yesterday mrs72 and I went out and did a fair bit of scootering around together, she on her new scoot. The !Vespa is a lot louder and not nearly as quick as that Kymco. At one point she asked to switch, she thought I might want to ride her Kymco around a bit. The funny thing is, even though she has told me several times she "hates" my scooter, you couldn't get the smile off her face riding the !Vespa. She thinks it's just the fact that it's super nimble and unimposing, and of course hilariously high quantity of character. What I found was that 50% more hp was amazing on her scooter, but even though it just goes effortlessly and is as smooth as silk, I really did miss that enormous character. Plus, even though the Kymco is physically bigger, the cockpit is much more roomy on the !Vespa, and it has less of the feet-in-front riding position, suits my longer arms and legs a lot more. The !Vespa, although only 4 years older than the Kymco and with roughly half the miles on it, genuinely looks and feels like a 40 year old classic, right down to having to nurse the idle at stoplights and the occasional stall. The newer Kymco is light years more refined. If you can get my !Vespa up to 50mph it is a riotous achievement that feels like you're about to win a prize. The Kymco just sails right up to and past 50mph without you even noticing... you could be sipping a cup of coffee while doing it.
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Turns out I had stacked the components slightly wrong on the !Vespa when I put the new variator pulley on. There's a spacer that's meant to go inboard of the pulley, which I put on the outside. Today I switched it back. Man, that makes an enormous difference!

So, yesterday with the spacer on the outside, the scooter felt kind of sluggish, top speed was right around 45mph but it took forever to get there. It's like the engine just didn't want to start revving until you got up over like 40mph. Now it is much quicker 0-40, but it's basically at the redline, or maybe on the rev limiter, when the scooter is going an actual ~42mph. That's basically the top speed. If you ride it WFO like that for more than about a quarter mile or so it starts to do a little but of surging, which I think is just burning fuel faster than the fuel pump can pump it.

So, next up is to replace the vacuum hose that's running the fuel pump with a larger diameter hose, maybe that'll improve the pumping efficiency just enough to sort out these running issues. Man, if only I had been able to get an electric fuel pump to work, this would be a snap.

IIRC last season the scooter was running right, it was running basically the same as now if the seat of the pants are any indication. But it would top out right at 50mph. Something tells me the taper of this J.Costa pulley is different than the stocker. CVTs are funny beasts. I had planned to swap to sliders in the CVT in order to get a little more top end and quicker acceleration, and I had considered switching to the J.Costa high performance variator to match this pulley, which is also purported to give both quicker acceleration and higher top end. The speed limitation right now is because it's on the scooter's redline and there's no more gearing available in the CVT.
Talking to myself here.

One thing about working on something frequently, you get good at it! Yesterday I did a little bit of work trying to get this scooter closer to it's intended state of running. Whole job took less than 30 minutes.

Issues I was trying to fix:
- scooter tops out at 40mph and surges when running WOT, should be more like 50mph
- if you idle for more than a minute or two, the scooter runs very poorly, barely runs when you take off, clears up after a few minutes, sometimes will die at idle
- extremely poor fuel mileage, probably <30 mpg! Should be >80mpg

So here's what I did:

- changed the spark plug; FYI this plug is hard to find like all parts for this scooter, and surprisingly expensive. When did basic copper spark plugs price skyrocket above $10 each? Anyway, the old plug was very, very black, covered in soot. It's been this way the last few times I removed it, but this time I know it's after running nearly a whole tank of gas with it "fixed". So I know it has been running super rich, no wonder the bad mpg.

- Replaced the vacuum hose going to the fuel pump on the theory that fuel starvation was causing poor running after idling and maybe the surging at WOT and poor max speed

- pulled the carb and put back the air line going to the ECS controlled air valve, this in hopes to fix the extremely rich conditions. Running it in open loop will require me to rejet and I have no idea what kind of jets to get or what size the current jet is. Orphaned carb! So I need to get it back to closed-loop so it will get >30mpg and not be super rich.

- replaced both fuel filters. The one between the tank and the fuel pump drained cloudy grayish fuel from the inlet side along with a surprising quantity of rust. The fuel filter between the carb and the reservoir was much cleaner but I replaced it anyway for good measure, along with one segment of fuel line on that side.

When I started it back up without making any adjustments or touching anything it fired up immediately and the warmup idle while on electric choke was pretty high but I thought maybe not higher than normal; I let it "warm up" for over a minute before taking off, mostly to try and get the fuel reservoir pumped up. Test ride proved a huge success. The scooter runs almost as good as it ever has now. Much crisper acceleration and top speed now is about 43mph indicated. Also, the idle was extremely fast after doing all this, which makes sense, since the scooter most likely runs at closed loop at idle so I'm guessing the ECS is properly setting the idle mixture now. And the surging at WOT/steady 40+mph is greatly improved.

The top speed is still limited much lower than I recall, last year I was able to consistently get this little guy up to 50mph and sometimes with the right wind and road conditions I saw as much as 54 on the speedo. There's a big difference in hp between 43mph and 54 mph. It does have a different variator pulley on it now, and it may be that the profile/angle of the J.Costa pulley will result in lower top speed unless I either put heavier roller weights in or switch to the matching J.Costa variator. But the scooter still does a little bit of surging at WOT. This problem really mystifies me.

The other mystifying problem is the misbehaving idle speed. If I ride it at 30mph and then stop, it might be idling at like 2500 rpm, so I adjust the idle speed while it's parked to get it to more like 1500, then run it up to 30mph and it stalls when I stop. So I bump the idle up enough for it to not stall and next time I stop it's back at 2500. I am guessing this is actually caused by the pilot mixture being way off and the ECS trying to auto-adjust both it via the air valve. It occurs to me that the air inlet (aka vacuum port) the ECS uses to adjust the mixture is much larger than the idle air bypass in the carb or really the butterfly setting when it's idling, so if the ECS detects a rich idle it's going to open the solenoid and let a HUGE amount of air in at idle, which will result in a way faster idle, not really just leaner. Just makes setting the static pilot mixture very tricky if this is true.

Alright, so today I plan to fire up the GPS speedo on my smartwatch to test the top speed and also validate my hacked speedometer is accurate since mrs72 swears it reads 5-10mph slow. I will put an ounce or two of Seafoam in the tank and fill her up again, get it fully warmed up and then re-adjust the pilot mixture. For all I know, bad pilot mixture could be causing both the surging and the limited top speed. Of course, it could also be electronically limited... the ECU does have engine speed calculation and programmed limiting.

If I'm to keep this scooter long term I need to either successfully switch it to a more normal carburetor & ignition setup or retrofit fuel injection onto it. If a wrecked 125-150cc EFI scooter pops up on CL, brother I'm on it. In the long run, I'm probably better off making this one even more retro and getting myself a used Primavera or Sprint 150 to use as a daily.
I reset the pilot mixture to 1.5 turns out and spent yesterday during the glorious weather running as many errands as inefficiently as possible and burned almost an entire tank of fuel. Scooter rolled over the 1K mile mark.

Idle was crazy high when I put the pilot at +1.5, so it looks like I was going in the right direction. I will probably put it in a half turn and try some more. The normal process of getting the engine warm and then tuning for max idle rpm is completely wrecked by the ECU adding air to lean it out, because if the normal best/fastest idle is rich, say 12:1, then the ECS will add air and with more air the idle speed will go way up, until it invariably detects it's too lean and turns off the solenoid, and the idle speed goes right down. So the trick is to set the static idle mixture to the magical lean idle that the ECU is trying to hit so it won't try to lean it out and cause this variable/surging idle.

It still seems to be getting pretty bad mpg. No trip odo but I was well into the 900s when I filled it up yesterday and just rolled over to about 1010 and burned about 1.5 gal. I'm sure the pilot is still too rich. Also, maybe that 85mpg is not to be expected when riding it at WOT pinned against the rev limiter the whole time like I was half the time yesterday.

I am now almost 100% convinced the WOT surging is the rev limiter. The scooter runs just fine all the way up to exactly 43mph and will simply not go faster, even down a hill. Hold it at WOT and it tries to maintain a constant engine speed with slight surging or hesitation to keep it from going faster. The J.Costa outer pulley I put on is probably a different profile than stock, so it might not make as tall of a top gear with the stock variator as it would with a J.Costa variator. I know the stock variator will go >50mph, so I might be able to tune it some to get a few more mph out of it. Eventually I think I will need a matching J.Costa variator which claims to have both a shorter low gear and taller high gear than stock, so if my scooter is really running right, I should be able to keep the acceleration I have and get back more than the 7mph I am missing.

50mph is kind of critical for suburban utility, since many roads I have to use are posted 45mph with plenty of traffic running that speed and the country highways tend to be two lanes and double-solid and 55mph, and nobody likes a scooter in the only lane going 12mph below the posted limit where you can't pass. Right now I just can't ride on those 55mph roads and I just barely keep from getting plowed over on the 45mph roads.
Turns out I had stacked the components slightly wrong on the !Vespa when I put the new variator pulley on. There's a spacer that's meant to go inboard of the pulley, which I put on the outside. Today I switched it back. Man, that makes an enormous difference!

So, yesterday with the spacer on the outside, the scooter felt kind of sluggish, top speed was right around 45mph but it took forever to get there. It's like the engine just didn't want to start revving until you got up over like 40mph. Now it is much quicker 0-40, but it's basically at the redline, or maybe on the rev limiter, when the scooter is going an actual ~42mph.
IIRC last season the scooter was running right, it was running basically the same as now if the seat of the pants are any indication. But it would top out right at 50mph.

I reversed the above mod, putting the spacer back on the outside of the pulley. Now the scooter runs a GPS verified 53mph wide open. It might go faster given a little more road. I guess all of the other tweaking and running a tank+ of gas with Seafoam got rid of the sluggishness, since it's not at all sluggish now. I mean, it's not like mrs72's 13.5hp beast, but it's as good as it ever was.

Mixture adjustment is still in progress. This is going to be a process. I'm not even confident that the screw is doing what I think it should be doing. Zero documentation on this carb is killing me. I am assuming it's like a Mikuni, turning in means lean.

Still runs kinda bad for a minute after sitting at idle for a long period, but it also idles really low and I have to nurse the throttle when it idles for a long time. I still think it may be the fuel pump not pumping enough while at low idle and it starves the carb of fuel. If I increase the idle speed then when the ECU kicks in more air because it thinks it's rich or whatever, then it idles so fast I can barely hold the scooter still. This remains the last thing for me to fix.

Mrs72 was right as usual. Speedo seems to read right at 3mph slower than actual speed from about 30mph to at least 50mph. So when it was stuck going "43" before, it was actually going more like 46. The current 53mph top speed is indicated 50.
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Alright, so I have a new idea. Y'all tell me if this will work.

The scooter has an oxygen sensor. It should read 0.45V when the mixture is 14.7:1. So if I clamp the air inlet from the solenoid to the carb and run the scooter at idle while the engine is warmed up, I should be able to monitor the O2 sensor voltage as I adjust the mixture until it reads 0.45V, right? Then maybe the ECU won't try to lean it out by adding a ton of extra air.

I guess we know what he meant, but the reality is information about repairing and tuning these particular scooters is nearly nonexistent. If someone else had done this work and posted about it on some forum then I would have been able to search and find it, then I wouldn't have to figure this all out on my own. So, down the line, maybe this can help someone else out. But I guess if this irritates the likes of cdc I can move this info over to my blog where he doesn't feel the need to post snark attempts.
After a couple of weeks of use, the scooter has been running great besides a bit of hard starting when it's hot, until yesterday when I went to take what would be the third trip to get ice. Wouldn't start. Later after the big party at the house I needed to get the scooter back up off of the sidewalk where it was parked and at least at the top of the driveway hill, wouldn't start. I had to push it up the hill.

Sooo... I guess it's back to the drawing board. I'm still unconvinced the carb is working consistently and I don't trust that ECS mixture adjusting thing. I guess I get to work on it again today.
Even after all the work, it won't start. I now think it must be ignition. I smell fuel when trying to start it, there's fuel in the carb and it's clean and in proper shape, but the spark plug was not consistently firing in the gap correctly and was instead firing across to the rim of the plug when not installed, who knows if it's firing at all when installed. It's a new spark plug. Just so frustrating. I think I'm going to go dig through the garage trash and see if I can find and clean the original spark plug.

EDIT: After 24 hrs. contemplating, I have concluded I must just have a defective new spark plug. Wouldn't annoy me too badly if this was a normal $3 spark plug you can just go pick up at Walmart, but it doesn't really compute for a $10 NGK spark plug to go bad after less than 50 miles.
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Well, I'm a complete idiot, apparently.

#1 the NGK spark plug I bought, and installed!, is the wrong one. I should have known this, because I have made the same mistake before! It's a CR8EH which is indicated for my scooter, but it's not the correct part. The "EH" is the problem. This is only "half" threaded. So the spark plug won't screw all the way in. The original, correct part, which I recall now is not actually original but I replaced it, is an Autolite 4303 which has 19mm of threaded portion on it, so it would be able to screw all the way in. No wonder it worked better.

Somehow as a side effect, I think I also might have gotten the threads cross-threaded in the upper portion. The half-threaded part screws right in until it runs out of threads, and the full-threaded one screws part of the way in and gets stuck. I ordered a 10mm back-tap to try and fix this problem without having to pull the head. Fortunately since it has good threads in the bottom of the hole, the back-tap may just work.

When it rains, it pours, I guess. Tough luck if I ever get this scooter working.
Well, I'm a complete idiot, apparently.
Good to still be able to laugh at ourselves, as the number of opportunities grows exponentially with age. I just had a good one around realizing the proper controls and settings on the pickups of my Les Paul, but we won't go there, as its about as complicated as getting the right spark plug. Fortunately I figured it out alone, all by myself, and will no longer complain to the band about the sound of my twin reverb and guitar setup, which had nothing to do with it :-) Maybe I'll just say "I fixed it" and leave it at that.
Well, the fact that I should have remembered trying that NGK spark plug, that's the big frustration. Then, I noticed over and over how difficult it was to get the spark plug lined up and threaded in straight with the plastic forced-air housing in place, I should have known this would eventually result in cross-threading the spark plug. So now I'm going to dremel away some of the cover so I can avoid this in the future, I guess I'll cover that hole with some duct tape.

I'm hopeful the back-tap will work. Worst case I have to pull the head, which will just be time consuming, and then convince a friend to fix it for me. I just hate missing great riding weather with my wife.
In a rare move, USPS has bumped their estimated delivery date of my special mistake erasing tool to one day earlier...


If this comes true, maybe back in the saddle for the 60% chance it isn't raining Sat.
I think maybe you should rename this thread !Vespa at War, then people can protest and choose sides. :lol2:
Is it me and the !Vespa both together at war against some unseen force trying to keep the scooter stuck in my garage in pieces? Or is it me trying to make the scooter work at war with the !Vespa who just wants to spend the rest of the season on the DL?

This is backing out the back tap with a 1/4" T-handle, 6" extension, U-joint, 10mm socket:


It was kind of a tricky job and I wound up running the back tap through four times with progressively more taper each time until the threads were pretty much perfect. Seems I hadn't likely cross-threaded it, but there were just some threads in the middle that felt damaged. It just had to clean up that one spot. 10,000x easier than pulling the head!

Scooter fired right up with zero drama as soon as the old plug was back in on the freshened threads.
Never heard of a “back tap” but good to know they are out there!

Same here! The 10mm one I got is only really useful for this one scooter. Most motorcycles are going to use 12mm or 14mm. Same company makes a kit with a 12mm and 14mm both in it. I might order a set just in case I screw up one of my other motorcycles.
After getting the spark plug problem worked out, it seemed silly to have a 100% working scooter. So I decided to attack it with my angle grinder and sawzall.

Truth is, I want to do everything I can to wring the most power out of this thing so I can have any hope of keeping up with mrs72 on her much quicker Kymco.

So... the scooter has a little bitty catalytic converter, which is welded to the side of an enormous muffler that does a surprisingly poor job of actually quieting the engine. If you're not familiar with these old large-frame Vespas, you might not realize how odd the exhaust is. The muffler is roughly rectangular and sits below the floor with entry and exit both at the rear on opposite ends. Header pipe comes down from the cylinder which is just below the seat, then winds around the side of the muffler using 4 90-degree bends. The catalytic converter is alongside the muffler welded into a heat shield between the front and rear 90-degree bends in the pipe.

So I went at it with the angle grinder and sawzall and got the little cat cut out, replaced its missing section with a piece of stainless tubing I had laying around. Tried clamping it in with two normal 1.25" muffler clamps and an impact wrench. Here's the result:

After about three tries, I finally got it to clamp and hold solid. The rear joint works fine as is, but the front joint leaks. The scooter is very loud with the leaky exhaust. Kind of sounds like a 45-rpm record of a chainsaw played at 33-1/3.

I was concerned that the little cat might cause too much restriction, and also that by running it too rich, I might have melted down the car. This is a "Euro-3" emissions vehicle, so it's pretty corked up compared to US-market-only bikes. Here's a shot of the cat looking down the throat:

That's pretty much a 1" ID inlet, you can see the honeycomb in there. Looks kind of free-flowing to me, but I didn't do any kind of testing. Doesn't look to be melted down at all. I just threw the part in the trash.

So, the reason it leaks, I think, is mostly due to the clamp design and the fact that the pipe is not a perfect fit. There's no perfect-fitting pipe available, anyway, so I plan to make this work. The clamp bends he pipe roughly into an oval shape, so it leaves potential gaps n the edges. I need a clamp that provides even tension around the perimeter of the pipe. I ordered some T-bolt type clamps to use instead, which should also look much better.

I also ordered some Permatex exhaust putty, so when the new clamps come in, I'll pull it all apart and put some putty on the inside of the pipe before I assemble it again, then put the new clamps on. Maybe I'll fix the leak. It will at least look better.

If this gets into the welding and get a friend's help phase, I might opt to just fab up a whole new exhaust system.

I took it for a test ride after all of this, which is how I discovered it's pretty loud. Scooter runs fine without the cat. Butt dyno is inconclusive.
Alright, 2nd time:


This time with some Permatex exhaust repair putty in the joints and better clamps. Still leaks, but a whole lot less. Next is to add some more of the Permatex on the outside of the joint and cure it with the heat gun rather than with the scooter idling as recommended, because the exhaust pressure is blowing the putty out of the joint. Then I'll probably wrap it in muffler repair tape and call it done. Anything more is a full custom exhaust.

Impressive bluing of the SS pipe! If this was a regular motorcycle header you'd conclude it was running really lean. Imagine how it it is 18" up the pipe by the cylinder head.
Well, my luck with this scooter frankly stinks.

I ran it the other day for the prescribed 10 minutes to get the Permatex to set up, and I actually restarted it a couple of times during this time. No problem. Then went out and did nothing but loosen the rear exhaust clamp and rotate it a little bit so it would clear the center stand better, and now the scooter won't start.

That's right, I did absolutely nothing, and now it won't start. It started fine like 10x in a row, then it sat overnight, it won't start. I charged the battery just in case that had anything to do with it, but it didn't. Just won't start.

I'm about ready to toss it off a cliff.

I had to run an errand yesterday when this one wouldn't start so I took mrs72's fancy "new" Kymco Like 150i. That scooter is a gem, but I still like the old rattletrap better. I did get it up to 62mph quite easily. It'll probably crack 70 on the speedo if you have the space, which I am guessing is more like 63mph actual. If it had a flat seat without the pillion separation hump, and a way for me to ride with my feet further back, then I'd just buy another one and let this Vespa collect dust.