Modern Vespa

Thank you. I didn't find one for the Stelvio either.

I will just do the usual break in. The speed limit on the back roads is 45 mph with lots of hills. I will just enjoy them sensibly with rich jetting until I've run a few tanks through.

When I dropped my engine a few weeks back, I found that the coiled fuel hose had shrunk and it was even shorter yesterday. The blue hose I had was hard as a rock. It's like 6 months old!!

A hillbilly farm fix was in order. Had some 1/4 " brake line kicking around. I will sleeve it with some tubing to keep the clamps from rubbing on the frame. I'm keeping it like this. The brake line is pushed an inch and a half into the fuel hose going into the frame and almost an inch into the blue line. I warmed the ends up with a heat gun so the line is molded to the bit of brake line.

I'm starting with 140/BE5/128. 50-120 idle jet. I'm pretty comfortable setting up the main, but the idle circuit was impossible the last time through. It would run rich no matter what jet I put in and the mixture screw did not seem to do much until it was nearly closed.

When I put on the Si26, things seemed more promising. It would rev out at 1/4 throttle on the stand (it wouldn't before) and the mixture screw seemed to actually do something. Worst case scenario, I don't get quarter throttle any better than before. If that turns out to be the case, I can live with it.

Are you still on the 26/26?
If so, definitely AC120/BE4 to start with.
Iron cylinders take a lot more running in than alloy. Extra oil for the first few tanks too.

The 26 will run richer because the flow velocity will be slower. As long as the reeds are good now.
A 30mm carb on a 125 motorcycle is not uncommon. A 26mm on a 190 scooter is not too much.
Hopefully need the bigger pilot jets too.
Any filter on this?

I was planning on running without a filter.

The 26 needs its own size filter. I suspect you don't have one and should neither buy one.

Actually, I couldn't have run out of fuel. I had 4 liters in the tank which is way above reserve. Maybe the 1% mix in the tank wasn't doing me any favors. I just wanted to have a backup until I was sure the autolube was working. It is.

Maybe the BR9ES is too cold. Either way, I could not get a spark out of it, even after cleaning.

The VMC spec sheet recommends a B9ES, but I'm wondering if a hotter plug might be better.

I've got no issues with the br9es in my VMC

Sounds much better than before. Is that the main jet done at 125? If it is swap the BE4 for a BE3. And see if it's any improvement.

Once ridden for a tank of petrol, quickly do the 2nd gear WOT test. If the main jet is not enough, running in will be wearing it out.

It's going to be way faster than the polini. It's a modern kit with better ideas. As ever with 2 stroke tuning, one big mistake and it fails. Would say your doing fine. Keep the revs and temperature down but ride it harder after each tank.

Once ridden for a tank of petrol, quickly do the 2nd gear WOT test. If the main jet is not enough, running in will be wearing it out.

It's going to be way faster than the polini. It's a modern kit with better ideas. As ever with 2 stroke tuning, one big mistake and it fails. Would say your doing fine. Keep the revs and temperature down but ride it harder after each tank.

Once youve established the jet that splutters at wot in 2nd how much smaller is the ideal jet? for example if a 135 splutters what jet should you come down to? 132? 130?

I went for a 20 minute ride doing between 35-40 mph. My temps quickly got up to 310*F. I am thinking I should up the main and idle jet. I'm at 50-140, 120/be5/125.

The biggest main I have is a 128. I will order some more in the130's.

Could the temps be break-in related?

The biggest main I have is a 128. I will order some more in the130's.

Could the temps be break-in related?

No. (That was easy )

it's been a while since I ran a BGM on Stella cases, but that seems like a big main.

I think you should bump the mixer to a BE4 to start. What throttle positions were you mostly at? More mixer than main, I'd think.

Didn't you buy a 50/100 pilot. I'd find out how rich that is first.

I went for a 20 minute ride doing between 35-40 mph. My temps quickly got up to 310*F. I am thinking I should up the main and idle jet. I'm at 50-140, 120/be5/125.

The biggest main I have is a 128. I will order some more in the130's.

Could the temps be break-in related?

Hard to imagine a Runleader shooting like that with your current jetting, vs an "event" spike.
They may have changed since, but the older VMC nuts had coating inside the threads that provided a "false (thread friction vs nut face) torque."

That plug looks super rich. Like practically fouled. Your temps still seem high for as gently as you're riding.

What gear and throttle position, rather than speed, are you riding at?

It did cut out at one point at about 40 mph and restarted right away. Not a soft seize, just rich and greasy.

Hmmm, I've never had a scooter cut out at 40, 30, 20, 10, or 5mph. I don't understand....

One thing I noticed that temps stayed around 260 while it sat and idled. Usually CHT's fall off a cliff once the load is off the engine.

That plug isn't seated. Dealing with a sensor there can be quite frustrating

Confirm torque on the cylinder nuts.

My wife's VMC leak tested on the bench, but not after the considerable vibration involved once riding. I ended up replacing those "optical tuning" nuts for standard nuts and Nordlock washers. Two years and no issues.

Get an M10x1.0 screw in sensor. You'll have to drill and tap the VMC head, but that's pretty do-able. FridayMatinee did an m4.5 on his and I feel like someone else has done an M10, but I can't recall who.

I did it on the Smallstate head and the BGM177 comes with that pre-drilled & tapped. That was actually a lot trickier, because it has an *angled* pad rather than just flat. Maybe it's Quattrini's way of making sure you've got actual builder chops to trick out their kits.