Modern Vespa

I installed the new piston and double-checked timings. 125 TD/184 ED/29 BD. Squish is .9 and I wanted .8, but I can live with it.

Naturally, I shot some video of the first start and a little up n' down the alley.

I still need to finish the floor rails, but I'll get to that sooner than later. I'm just happy to have it back on the road.

I also fired up the Sprint now that I put a SIP Road 3.0 on to replace the mystery exhaust that P200 motor came with. I'm wishing I'd opened up the intake when I rebuilt it and put the Malossi on it, but it still REALLY woke up what I've got. That'll need dialing in, for sure, but both bikes are more than a little ridable at this point .

Oh yeah! Third time is most definitely a charm!

Way to persevere and give us all hope to do the same

Good going! Now it's time to ride it like you stole it. 🙂

Just catching up on this and I am at a loss for words… sorry man. At this point I'd look for evil totems and cursed tikis. No other explanation.

Godspeed amigo! Hope it is sorted for good now.

Wait..
You just did a wheelie, in shorts?
Why have I been shopping for Kevlar-assed jeans and FF helmets the last few weeks?

It's all good, BN.

I just got back from some errand running and other than the horn deciding to fall out (I put the clips on inside out for some reason) and a couple carb tweaks (moved the needle clip up to 3rd for richness at half throttle and it still has a little bit of richness at 1/3rd to sort out), it ran great.

Once it got onto the main, it was happy as could be, no fuel starvation evident with only half a tank of gas, so the pump is working as it should.

I had one really scary moment heading back to my house. I was on the through road, doing 50 or so, and an oncoming car came across the center turn lane INTO MY LANE AND WAS HEADING RIGHT AT ME! So I was literally playing chicken with this dude at a 100 MPH closing speed. I just jumped on the brakes to buy time and after a couple of the longest seconds of my life, he turned left into the Subway that was on my right, but I literally thought I might be about to die.

Even before that, I didn't push it too hard because I have broken sensor wires on both my CHT and EGT and while this setup is close to Known Good, that was on the old piston so I chose not to risk it. The broken CHT wire is right at the base of the sensor and I tried to fix it, but it wouldn't hold, so I have another on order and the EGT I can fix, I just didn't feel like rolling around on the floor to deal with it this afternoon.

Oh, and when I was reinstalling the floor rails, I came up one end cap short and couldn't remember where I'd put any of my spares. I'll steal one off the VBB since it's getting stripped down next, but again, just didn't feel like messing with it today.

But all-in-all, things are running solidly, and it's right as the weather gets perfect for riding here.

Umm...I'm a slow learner?

This port timing is much better. Well set up, this will be fast. What's the ignition timing and jetting right now?

Remember kids, don't do this at home without the proper protective gear.

It's at 55 Idle, 165 Main, KLK on the 3rd clip. I'll have to go back and double check timing, but I believe it was 17 BTDC at 7,000 RPM's with a SIP Vape variable on it.

It was already pretty close to dialed in before the crash. I leaned the needle one notch yesterday after running errands and am going to try leaning it out one more because it's still rich at 1/3 throttle--which, naturally, is right where it lands in 30 MPH speed zones.

And don't worry, Nomad, when I was running errands, I was in Full Spaceman Attire with fullface, jacket, pants, boots, and gloves.

Coffee Spit-take on the the totem picture! LOLZ!

I mostly wear a three quarter helmet or bicycle helmet, flipflops, shorts, and a t-shirt on most rides, especially during Covid because I work from home. I know I'm a poor role model. To each his own. Don't hate me.🤓

That main jet seems big. Not such a great issue except that fine tuning the mid region of the needle will be very difficult if the main is too heavy.
If you ride with all your safety gear on, at 3000 rpm in 2nd, then suddenly go full throttle, it should take off like a scalded cat, while floating up the front wheel. If this doesn't happen this main jet is too rich.
Pilot jet looks a bit heavy for a PWK too.
Getting close to done. You can ride all winter where you are now.

The pilot just wants to be that big. I tried taking it down and even at 52, it started hunting a little when returning to idle.

For the main, I still need to figure out where it wants to be now that fuel starvation at WOT is not making it seem like I was lean when I really wasn't.

New CHT sensor is due to arrive on Friday and my wife is headed over to the UK for ten days to see her mom, so I should make some good tuning progress this weekend, even if it may rain on Sunday.

It's a PWK 35? On a 177?

PWK 34

Should be around 45… if is bigger than a 30. And that's with a 210

I'd recheck the timing.

Especially if you've played around with the squish… I thought I was at 24deg at idle and it was actually something like 20deg and it messed up all the jetting tests I did before…

The idle jet has always been richer than it "should" be, but I pressure test after every build and it's leak-free, so at some point, I just view it as an "it is what it is" thing.

I never check timing at idle because it's just not accurate. I check it at 4,000 RPM's or so to get a good measure for static timing and at whatever my peak power RPM target is (so usually 7-8k on this motor).

I'm still going to re-validate TDC and timing this weekend now that you point it out, though.

Worth rechecking.

If your revs are hanging (hence the need for a larger idle jet) when you roll off the throttle, that must be happening at less-than-4000rpm

You got to see if the timing is advanced enough at that rev range to give the fuel/jetting enough time to burn.

Timing effects jetting a fair amount in my experience.

Glad to see you back on the road!
Side draft carb tuning - cheated and went smart carb...
Oh, and Greg Brady idol.

Always a good idea to check the previous TDC mark before strobing timing. Been caught out by that a few times.

How many turns out is the airscrew? Different carbs each have a target sweet spot. 1.5 turns is a good target if you have no other empirical information.
The too big pilot jet not wanting to be smaller, could be a sign that either the airscrew is too far out or that the needle diameter is too big. When you started it in the last video it did sound lean, even for a cold motor.

To check the needle diameter, ride at 1/8 to 3/16 throttle and decide if its rich or lean. At this position the diameter of the needle is dominant. If the AFR is working about 11.5 is the target for 3/16.

I'll see if I can find time to get it on the road tomorrow after work. I know I won't have time tonight, plus I still need to re-check timing before I put a bunch of effort into carb tuning, as 108 reminded me.

The air screw is, IIRC, pretty close to 1.5 turns out, too. I spent a lot of time this summer swapping idle jets, which is a PITA because you have to take the whole float bowl off.

If 1.5 turns and with the video sound, then that's confirming it without even riding. Needle diameter is too big. Any thinner needles to try?

Not off hand, but JetsRus does

I ordered the full range of KLG, KLH, and KLJ. I'd almost done that earlier in the summer, but never got to it.

I expect they'll get here in a couple days and I can make some progress on this thing.

My new needles were set to arrive today, but they didn't make it, so now they won't be here until Monday.

In the meantime, I fixed the CHT, which wound up being the wire, not the sensor, but either way it's fixed with the usual blood sacrifice that happens whenever I have my arm stuck up in the tunnel. Good thing for me I got a fresh tetanus shot after my wreck.

I also added a battery using one of the pair of AGM power chair batteries Scott suggested. That, in turn, meant that I now needed to get everything onto a switched power source, which meant shifting stuff off the DC in over to the headlight circuit, which is on a switch along with the parking, tail, and brake lights. So now I can switch everything on or off at the headset, nothing wonky required and I no longer have to deal with my turn signals or GPS speedo not working at idle.

I also ordered a small, cheap voltmeter that will live on top of the battery so I can keep an eye on things, charge-wise.

So a lot of work and cussing for what looked like no changes whatsoever from the outside, but all good stuff.

Now, it's raining and is going to for much of next week, but hopefully I'll get some breaks in the weather so I can start working on the carb setup with the new needles.

Added a voltmeter onto the battery so I can keep an eye on it.

Once I decide about final battery mounting, I'll clean up the wiring, but it's nice to know what's up with the battery so I can throw a charger on it if I need to.

That molex connector hanging out in the corner can be hooked up to a charger or my AFR meter if it's installed.

I got a two-pack of voltmeters, so I'll eventually do something similar on my Sprint, too.

What voltmeter did you get - I'm liking that one...

It's nothing special. Just a pair of motorcycle volt meters. They make 'em in all sorts of colors, too, if purple or green or blue is more your speed, too.

The rain they forecast for today didn't start until mid-evening, so I finally had a chance to swap out the needle to a KLH and move it up to the 2nd clip and get it on the road a little after work today.

The mid-range is much better from 1/8 to 1/2 throttle, so the richer diameter did good things there.

Once it gets up onto the main, it's stuttering a little, but I can't quite decide what it's trying to do. The low end of 4th gear, specifically 4,500 RPM's/48 MPH, it stumbles and almost feels like it's not getting enough fuel or it's fluttering like it's getting ready to seize, but temps are fine (stable at 250F after about five minutes) and once it gets past that, like onto the pipe, it sounds much better.

Maybe I'm just far enough outside the power band that the pipe can't do its job, but I've never had this problem in the past. If I keep in 3rd until I'm up to 55, or even a couple MPH less, I can get into 4th no problems. The power band just seems a little narrower than it was.

All-in-all, though, the bike is running well, it just needs some more time and attention to get the jetting dialed in.

Good the diameter helped. What happened with the pilot jet and mixture screw? Should have got richer and now at 1.5 turns it runs with a pilot jet in the 40's.

The 4,500rpm stutter, as the CHT temperature is low, it is too rich in the middle. Before buying more needles, leave it all where it is and get the main jet as lean as it will go. Ride at WOT in 2nd and 3rd and lean out the main. If you get it barely stuttering, then drop two jet sizes, its normally about there.

I haven't done anything with the pilot and mixture screw or main yet. They don't really seem any different to me. I did the needle swap because it was quick and rain was coming. I have lots of needles to choose from, though.

I'll probably work on the main next, then get back to the idle.

And I threw a Table of Contents onto the first post. Maybe too clever for its own good, but then again, so am I.

Pilot jet should be first done. Although it won't be the last time its done. Every step it will be getting faster now.
When leaning down keep an eye on the CHT and listen for detonation. As its now running smooth but not well, any coughing or bogging will now all be lean conditions and cause for immediate concern. ie stop and change something richer.

When a needle/jet collection gets big, then you start ordering doubles you forgot you had. How many times have I done that.

I went through and "circled" all my needles on the chart after I ordered my first couple duplicates. It makes a big difference in both avoiding duplicates and also knowing what my options are for making changes without ordering more.

I also have them all stuck into the top of a cardboard box that's laid out more-or-less the same as the chart and labeled so I can find the one I need in short order without having to look at twenty needles through a magnifying glass. (This way, I should only have to look at one).

I'll take a look at the pilot jet next. It was frustrating before because it just didn't want to richen up.

Maybe this is informative, but as it is currently, the bike starts pretty much first kick, every time when cold, even after sitting for a week or more, with no choke and no throttle. When it's warmed up, though, say after I've ridden it somewhere on an errand, I'll come out of the store after five or ten minutes and it almost never starts first kick, but if I give it just a tiny bit of throttle it starts just fine (probably getting it off the pilot jet to start it), and will pretty much immediately settle back down to idle.

Thanks as always for the guidance, Jack!

I made some major improvements on the jetting tonight before it got too dark to ride safely or read my CHT at speed (It has a light on it, but it needs adjustment), but things are looking much better.

Dropped the main from 168 to 162, the needle from KLH-2 to KLG-1, and now have moved it back to KLG-2 because it was too lean at half throttle set up like that. 1/4-3/4 throttle was feeling pretty good, but a little rich, on the KLH-2, but first clip was way too lean. I think that dropping the main helped with that.

The idle, though...something's just not right there. I put the biggest jet I had, a 160, in and it's a little better, but still pretty lean. I'm thinking maybe the passage in the carb is blocked for that circuit, so I'll have to go get a new can of carb cleaner and hit it with that tomorrow.

As of right now, I feel like I'm on the cusp of success. It was running better tonight than it has since I blew up the old cases.

I'll try to get out and capture some action footage tomorrow.

I thought this was your paint thread…

Ever heard about of shipwright's disease? It starts when you replace something like one of those little cleats and find the deck is a little sponges. Before you know it, you've rebuilt the whole boat.

I'm just screwing with you, at least modify your title a bit now that we are jetting carbs

I still have one floor rail end to install, so technically, it's still a bodywork project...

Are you gonna make it yourself on a lathe or a mill?