Modern Vespa

I'm completely over it.
I dropped the motor a year ago and tested for air leaks, shortly after my first rebuild, and it held 5 psi for hours.

The thing is , I've been chasing my tuning all over the place ince then.

I currently have a P125x with Malossi 166 kit. Case matched and everything flowed or whatever you call it with a Mazz race cut crank, Si 24/24 carb and a Sito Road 2.0 and a Vape variable ignition system.

Oh and a new S.I.P fast flow with the bowl to main jet passage drilled to 2.5 mm
And their filter opened up like a heart.

Jetting, and here's the drama,
Main stack= 130 air/ BE4 mixer/140 main!

Slow circuit is a 50/???, I can't read the second number currently and can't find my magnifier.

Thing is it's lean at WOT when I do a proper plug chop.
A wisp or a ghost of color you really have to look for and to narrow! Electrode being white as well.
I don't think I'm getting the revs out of it that I should .

My cheapo Amazon multi tasking hour meter, CHT meter and Rev counter shows me the highest rpm to be 6995 @ gps Speedo 55.

My Timing at idle is 19.5 BTC

I don't care about the speed, I feel I'm not reving out enough.

Fuel flow is was so much better then my stock, Dick Trickle, I was getting!

So I plugged my engine up and put 5 psi in her again and it's holding.

Any ideas why the high main jet accompanied with lean chop?

3rd and 4th both stutter out at max rpms, can feel the power rapidly stuttering.

One last question, if I can upload a short video, when I slowly rotate the crank my Guage jumps around considerably. Settles back to origanol number almost istantly.
Is that normal?

So I don't know what I'm asking.
It runs but I'm missing something in my set up that isn't allowing full potential, I believe.

Thanks for any pointers

Sorry I can't load videos

Timing at idle should be around 23deg at idle for a Vape sport ignition.

Because at 19.5deg idle, at 7000rpm you'll be at around 14deg btdc which doesn't make sense.

First off, you shouldn't be checking timing at idle anyway. You need to be up in the 4-6k RPM range to get a good, accurate reading.

As to why you're lean...hard to say. Have you confirmed that you have flow all the way through the carb? Tried different jets? Just because a jet is *marked* 140 doesn't mean it's a 140 unless you've measured it with a pin gauge.

Now that's all out of the way, we can get to the root of the problem, which is that you need to look at your port timings to figure out what's going on.

Measure your port timings and your squish. I'm going to guess that your timings are too low, which is why you can't get enough RPM's. The Malossi is a relatively revvy kit and likes higher timings. Do you have any base gaskets/spacers on the motor?

As a bit of an aside, you said you have a Mazzy race cut crank, but not if it's a 57 or 60mm. I assume the intake timings are 118/6, but the intakes themselves are not lengthened. That's not ideal, but it's not killing you, either. Nothing I'd worry about if you're not splitting the cases for other reasons.

Finally, the SR2 isn't doing you any favors at this point. You'll get another 500 RPM's on top and a little better curve before the peak just by going to an SR3. Any of the Big Boxes will also do right by you. I'm not saying you *need* a different exhaust, just that it'll be easier to get 8,000+ RPM's with a newer exhaust design.

We can get you there, you just need to be looking at the right pieces of the puzzle.

I thought I was miss understanding something.
I miss read what somebody was saying.
Will re time but question is , what kind of behavior am I seeing out of this timing I have now? Tempeture wise and what not?

If my gauge is correct It runs a high as 220f. Does that make sense given the incorrect timing?

As far as flow thru carb how do I confirm.
As far as jetting I've tried a 130 , 132(I think) and a 135
All from S.I.P or Scooterwest.
Seems like I had a 138 that caused problems and I pitched it.
But the all acted accordingly as I went thru them.

Ya I'm going to have to learn about port timing!

When I bought this Scooter it had just been setup by Scooterwest and I assumed it was all done or done correctly.
Given the amount the seller paid for the install.

But no better time to learn

Ignition timing too close to TDC means there isnt enough time for the fuel to burn before the piston moves back down. Usually means you end up with a huge main, but with lean conditions.

The cylinder is designed to with a specific ignition timing. I can only think of "modern fuel" and "high compression" being the only reasons why you might want to retard the ignition.

But most modern kits factor this in already so if its 23-24deg with a variable ignition system, then thats the number.

but as CM mentioned, if your squish is not to spec, setting your timing to any number will be a waste of time.

Issues been going on a while. As said get the timing done better.

That plug is not looking great. Jetting is lean. The stutter is lean misfire. Good idea to take the head off, check squish as suggested. And confirm the piston is not damaged.

The idle jet should be at least 50/100 to run well.

If you want the original filter fitted use an undrilled one. Heart drilling is really just for stock.

Main air should be AC120.

Lucky for you, I did a video on troubleshooting the entire fuel flow system about a month ago.

But even that isn't going to help if you don't get your port timings and squish set up right.

You didn't say if you're running a 57 (stock) or 60mm crank. If you're running the 60, it makes all of this a LOT easier, because you have 3mm of space to work with to get it all set up.

The VERY short version is...

Port timings are an expression of how much of the rotation of the crank each port spends open and allowing mix and/or exhaust to flow through it.

To calculate them, what you need to do is measure the distance from the tops of the exhaust and transfer ports to the top of the cylinder (the "deck").

Then, measure the distance from the top of the piston to the deck with the piston at Top Dead Center (TDC). You'll feed all of those values (to the nearest tenth of a millimeter) into a calculator and that will give you your timings.

I'm out of time for now, but if you search within NSM, you'll find a wealth of material on port timing. Ditto for squish.

To answer the crank uestion it's 57!
Thanks for the help I will watch your video and get researching port timing!
Thanks again.

Well, I will re set my timing, check my squish, and learn about port timing, but that being said, your statement above gave me wood!!!

Thanks for your help, and I've got some work to do!!

Thanks Jack!!!!

This post was not quite
What we were hoping to see
Try again, perhaps?

This post was not quite
What we were hoping to see
Try again, perhaps?

OK so I plopped in a 120AC jet, set timing at 19 BTDC at 5800 rpm's, 23@idle.
Checked flow Thru of fuel system and carb per Chandlermann's video.

Haven't checked squish or port timing.

Took her out and she is rich and bogey lower rpms starts cleaning up nicely at or past half throttle and starves for fuel at about 6600 rpms.
So there is more there but am I introducing an air leak only at high rpms?

Would the port timing not being optimal cause the starve and lean out at top?

You can't be at 19deg @5800rpm and 23deg @ idle (1200rpm).

Did you use a degree wheel to measure the degrees to make the marks?

What makes you think its starving for fuel at 6600rpm? Any video/sound recording?

I thought you had fixed the air leak. It was noted earlier on that your cylinder timings and squish might be contributing to the bike not running as expected. Unless you know what the timings are, it's just guessing.

Lots of good advice since my last post.

First off, one of your timing numbers is wrong *or* you're not running a Vape Sport ignition. 1200 and 5800 are only two degrees of advance different (-3 vs -1). That's relatively minor and while it might be limiting power, is not significant enough (if accurate) to limit the performance.

If your measurement is off, however, you could absolutely find yourself so retarded that the motor can't rev past some point. I've made that mistake myself before spitballing where to set the stator on a fresh build, and it leads to behavior that can feel like fuel starvation as the motor misfires and/or backfiring/power loss.

So at this point, I'd make absolutely certain that TDC is set correctly and that you've calculated timing accurately off it.

Can you confirm how you set timing? i.e. how you found and TDC; how you calculated your timing from there?

Photos and videos always help in case we're failing to connect on terminology. This.

Any CHT data would also be helpful.

If it's starving for fuel when flow is otherwise adequate, then the main is waaaay too small and at severe risk of seizure. Given that you have an absolutely massive main jet, I don't think that's the case.

If you want to know what fuel starvation feels/sounds like with an adequate main jet, here's my video:

That was on my Malossi 210 with an undrilled float passage in an otherwise re-worked 24/24 and a 132 main.

Note the dieseling after the second starvation instance, too, another clear indicator that the motor is starved.

And we still need to get some measurements for port timings and squish, but I'm putting those on the back burner until we're sure you're not going to blow the whole thing up.

This.

I've spent way too much time jetting my own engines when timing wasn't set up properly and it's impossible to get it running well.

You can't offset wrong timing with different jets. It's just non-negotiable. You'll just end up chasing your tail.

Fuck it, I'm going to sell it!
I've got a fever today and to many know it alls jumping my shit.

Gear down big shifter. Nobody's jumping your shit and nobody is coming off high and mighty know it all.

You asked for advice and got good solid advice.

It's tuning, there's no easy button.

Can you throw all the stuff together and make it work, yeah. But, as you're finding out it's not optimal. And to make it optimal requires a through systematic approach and an application of practical processes that have been tried and true.

The knowledge and expertise is basically being spoon fed to you. We can't turn the wrenches and check your timing(s) as well.

I get it, you're frustrated. We've all been down the same road. If you want a hot rod, you have to grind it out and do the work. And it sucks.

Or you take it to somebody and hand over a big bag of moneys and get a tuned bike in return.

It's easy to get frustrated with vintage Vespas.

And it seems you had some bad luck with the ordering of parts which is pretty horrible to begin with.

I'm the first person to hold up a hand and say I didn't know anything about anything a few years ago and the gents on this forum helped out. The guys who have answered your thread, combined, have easily built/rebuilt/molested 50+ Vespas onto the road.

Hundreds of hours with my own builds, making expensive mistakes and constantly asking everyone who's ever built a Vespa, you find your way.

It's rooted in basic mechanical engineering. That's why we're pretty certain about elements you're coming across that aren't working. There's a lot of black and white with Vespa engine builds, there's no grey area. Works or it doesn't.

Tuning isn't for everyone, it doesn't mean anyone's clever. It's a ton of investment of time and money. Just the tools to work on them. I have 2 big boxes of tools separated for smallframe and largeframes. There's not many shortcuts.

Had a handful of friends brought px200s and most of them sold them. Most don't want to spend so much time figuring it all out, which is fair.

+1 to both Greasy and 108

You have a number of what are, to us, minor issues to resolve. I will also say that the first time any of us tackled them alone in our backyards, driveways, or front walks, we were just as frustrated as you.

And I promise you that we didn't have anywhere near the level of support that's out there today, whether it's me drinking coffee and pontificating or youtube videos or a wealth of other information. All we had were the Haynes Manual, and most of what's in it fell into one of two categories: Things that were wrong and Things that only made sense if you already knew them.

So, yeah, right now this all feels very frustrating and a little overwhelming because you don't have the experience to be able to see that they're minor. To us, they're just, basic tasks you perform when building a motor. I know that I forget that sometimes--I just helped a guy here in town with a rebuild and I couldn't count the number of times he said, "I'd never have known that" about some little trick or check that I take for granted now.

Which brings me to my next suggestion...see if you can track down some local scooterists to help you get over the hump. You're in SoCal. Compared to Nashville, SoCal is practically infested with scooterists, even if a lot of them ride Lammies. Scooterists are notoriously curious about other people's bikes and usually quite happy to help out with mechanical tasks. Especially if you have beer.

In the immediate-term, though, the first thing I'd do if I were you and looking to minimize effort is tackle your ignition timing. No opening of the motor itself, but if you don't have one, you'll need a TDC Tool and a degree wheel to accurately find Top Dead Center. It's about a $10 tool, basically just a fancy M10 bolt. You can buy a degree wheel, or just print one off the Internet.

Once you have those, you can confirm or fix your timing. Don't worry so much about getting it absolutely dead-on to start. We're just making sure you're not 15 degrees too close to TDC, which I suspect you are at this point.

Regardless of anything else you deal with, as 108 said, "you can't offset wrong timing with different jets." Same goes for air leaks, which you fortunately don't have at this point.

It may also turn out that once you get the ignition timing sorted, the port timing gives acceptable performance and you can decide to just run it from there.

Finally, there are a lot of folks who let the perfect be the enemy of the "good enough" when it comes to these motors. They miss a lot of good riding days as a result. I'll say with pretty high confidence you're not in that bucket--you bought this thing to ride, not obsess over--so hang in there a little bit longer, get it back on the road, and then you can decide if these things are for you or not.

And even if you do decide to sell it, you'll get more money for a well-running scooter than a project. Not that you'll ever get out what you paid for it, but that's why these things are hobbies, not investments.

I feel your frustration. I have been working on a mildly tuned engine for 2 seasons now. It runs quite well, but still has some issues to solve. It's my first one. It's a lot more difficult than expected which is how it goes for most people the first time through. It is hard for even experienced people to sort out why an engine isn't running as expected. Usually, it's a combination of things and a lot of trial and error. If someone could put their finger on it and say "change this", they would. Really helpful bunch of folks here.

I have been turning wrenches for decades on VW's, but Vespas have made me lose my shit to the point of kicking my scooter over on it's side when it wouldn't start. I'm a psychologist…53 years old, cursing like a sailor in my driveway, taking a running kick at my bike while the neighbors watched.

I didn't look at mine for eight months after 18 months of not getting there. It's part of the fun, the self loathing.

Wait, I got a LOT solved in the garage with Covid.
If you can't get up it's Google time!

I had that exact setup with my first Vape.
Also ignored the convoluted instructions on page six of the booklet.
That was stupid. Then again, those instructions are stupid.
It's not done with the flywheel on. If you use the flywheel to time it you'll add time and confusion, and smash your washer.

Print out a paper degree wheel a bit smaller scale than those made for timing with a flywheel on, and glue it to cardboard.

Lightly screw down the base plate so you can freely rotate it.
Piston stop in (only use a screwdriver or flashlight peek through the hole to confirm. You can be off a few degrees without a stop).
Rotate the rotor with the degree wheel counter-clockwise until you bump.
Set degree wheel to 0.
Rotate clockwise until you bump. Divide the result by 2. Remove the stop and continue rotating clockwise to that number. Mark anywhere with a sharpie as TDC.
Rotate the degree wheel to 0.
Rotate counter-clockwise to whatever advance you want and use a screwdriver to line up the marks as at 2:00 in this video.
That's the dotted line in the graph. The curve is the CDI.
The CDI you have is an added complication, but IIRC I ended up with the dotted line at 23 as best advance before switching to static (it's not actually static either, just called that).
140/BE3/125mj, 52/140 with a drilled/Cosa filter.
120/BE4 was a nightmare combination at low throttle with that kit.

Don't go clockwise first as in the video.