Modern Vespa

Hey guys,
Going to port match my wife's px that we got from Patrick (oopsclunkthud -- great bike from a super guy, btw) to bolt-on a Stelvio.
Been watching FMP's video. He ported a 2005 or so PX and avoids one area to avoid breaking through (see pic).

This bike is a '78, so I'm hoping there was maybe more meat behind that section before maybe Piaggio cut down on aluminum there.
Should I still avoid that area? This a pnp project so my wife can keep up with traffic, on a known quality build with hardly any miles. Really tempted to just bolt it on and see how it goes.

Nothing to lose by bolting it on, if it doesn't work as well as you want you can try porting it then.

I'd be tempted to just do this. Plus itd be info for the MV community that will be following in your footsteps.

Gosh, i'd spring for getting more material welded to my cases. It would be VERY convenient right now to take the opportunity to do so. Mr. Gick can weld that up lickety split.

Are you splitting the cases? Reason I ask is if so, then Whodat has an excellent point...

Wasn't going to. I'm basically following FMP's PNP install idea. Already done with the carb box/intake work to match the 24 carb. Taking Sunday off for my neighbor's sake.

At 27:30 he sticks his index finger behind that area. The '78 doesn't have that empty space, as far as I can feel. I'm hoping somewhere between then and 2005 Piaggio decided to save some aluminum.

I've had multiple 2005 PX150's. I've only gone as far to split and gut the cases to match and flow the stock top end to the case. There wasn't that much extra meat to work with. Larger case porting means that more fuel can get in there to cool and lube both the crank and piston. And if you're going to swap on a cylinder kit, you should be renewing the cruciform, crank bearings, and seals. Also check for any sort of wear or chipping on the loose gears too!

Oh, i was just assumed that the cases were (are) going to be split.

Just bolt it on.
Base port matching makes little performance difference with low cylinder port timing (like the Stelvio has).

Do what the REAL tuners do... grind that mofo till it matches, and once you see daylight thru the grind zone, just grab that JB Weld & fix it !

Just bolt it on. It's gonna be more than enough for your needs.

Ok, bolted it. Zero porting. Still can't find a torque spec for the cylinder head screws that add to the bolts.

I'll need a few days work before I can kick it. I'll follow-up with my impressions as far as how it feels.

All your advice was much appreciated.

watching....

I was gonna suggest rolling out to CM2's casa with the empty cases and a six pack of something good to get the meat added, but as it is, I'm just going to follow along for your impressions.

He's always welcome. Have wondered the same on torque.
Would also highly recommend: chase all the VMC threads on the studs and on the bolts. They are coated. If you are unlucky - they could stick enough to strip your case threads while trying to put torque on them. (the note sticks to the stud, and when you try and tighten - all you do is bottom out the stud in to the case, then strip the case as it tries to go deeper).

Wow, thanks for the offer!
If I didn't know the seller, and that it's a known quality rebuild with hardly any miles, I'd have gone through it all. Seemed like an ideal PNP candidate.

You're right about those coated long bolts. I cheated on the bolting. Just used fresh nuts, except for one of their extension bolts for the cowl.

Torque spec is 14nm on the bolts and 11nm for the screws. Assuming I'm good

Hey!
Thanks.

Took a 10 minute break-in ride today. Feels great!
Not opening her up yet but the torque is definitely there. Gearing feels made for this displacement.

Started first kick, after four before remembering the key switch

Any difference breaking in an alloy kit?

Also turns out I had the meat all along!
FMP's video I posted is a 2007 px. Piaggio cut out that meat somewhere between 1984 and then to save aluminum.

In my experience - doesn't take long.
Not like you are going to break in the nikasil.
Just the rings.
Usual rules apply.
Rev it through its paces reasonably.
Don't hang in any gear.
Let it get good and warm a handful of times.
Rinse and repeat.
Bob's your uncle.

Poor jetting does more damage than any other thing. Buy the time several jetting episodes are completed the running in period is usually over. But be careful with the sustained WOT for a while longer.

Thanks, Jack.
Current jetting with the bolt-on VMC, Road 2 and 24 Spaco:
Idle jet 50/120
140/BE4/128 main stack.
Felt really good during one 10 minute hilly run. Dies while idling warm when choke pulled.
Keep going with this setup?

You're not saying its spluttering. Need to find out where this point is. Seems like a waste of time but quickest way to the end with no cylinder damage.

Which air filter? (hint: None, Vortex or T5 are the only acceptable answers).

Carb float bowl is drilled to 2.1mm or bigger?

Fast flow tap of some kind and large under tank inline fuel filter in 7 or 8mm pipe?

Ok onto jetting. If all answers acceptable and still saying a 128MJ is good, then you must fit an AC120. BE4 50/120 all good and can stay.

Unfortunately it's raining all day here, so I won't be able to get it to splutter today. Only went to 1/2 throttle yesterday on the hilly break-in ride.

Air filter is a stock 24 (drilled) for now. BGM fast flow tap but no filter.

Carb bowl not drilled. A BGM(2mm float bowl hole) upgraded carb arriving next week.

I've got 130 to 136 mj's and a 120ac to try tomorrow. Can you recommend a starting point mj?
Thanks again!

Changing main jets in an SI carb is so trivial that I don't think it matters. I'd start with the 130, and if that doesn't splutter, go to the biggest MJ you have.

With that large of a main jet I wonder if the undrilled float bowl passage is restricting fuel flow instead of the main? Watched a video of a guy putting in a 160 MJ never spluttered because the passage couldn't flow that much fuel.

Dropping to a 120 air corrector should help richen it up a bit. I switched from a 160, 140 then 120 to keep my ideal main jet within a range I had a good selection of.

Rain let up today, so I took it out. Stop and go ride, as is the only choice here.
Changed main jet to 130. Couldn't find my 120ac in my bin of brass bits until afterwards.

130 cleared a little bog at mid throttle, but no splutter.

Threw my phone in my pocket and recorded a few blocks, hoping you guys could give it a listen. Video is dark, of course. Couple of "California (rolling) stops" in second gear there.

I'll try the 120ac tomorrow.

Feels great, btw. If anything, it doesn't feel like it "breathes" like my ported Malossi, but I could be very wrong about that at this point.

Ok - one man's ear.
1. You are a little chubby - down low - but its nothing to be ashamed of. Good for break in.
2. You hardly got on the main jet! 🙂 seriously - its not gonna just fall apart on you. Rev it out a little without hanging at the top. Let it break in. Sounds like you are jumping off it at 5K.

That's my OPINION.
Other's may have better experience or different thoughts.

AC120 is essential. Ride with less at your peril.

The stock filter is not great makes jetting less easy and is restrictive. Better off without it.
Putting a filter under the tank means the filter in the carb (was it ever it pc to say under the chinamans hat?) can be removed.

Carb must be drilled when non stock or many bad things happen as soon as its at sustained WOT.

The carb box top changes the jetting. Always put it back on, even if it is annoying.

Sounds ok to run in as it is. Its not going to blow up at that rpm you're riding at.

My engines must hate me cause I abuse them way more than that! They are screaming before I shift.

Yeah, I shift at about 8,200, but my motors are Not Normal...

Thanks
Only the first acceleration is in first gear. The rest are 2nd gear, that may make it sound chubbier{?)

I did rev it out before trying the pocket video. No luck trying to splutter it.

You're right. I'm letting off at around 4/5k. Wanted you guys to "see" how it returns. This is also a neighborhood with stop signs at every corner. 50 or so yard runs.

oh pissing contest If I take my 221 to 9500 in 3rd (77mph) and slip into 4th, its right in the power in and still floats the front wheel. It's quite exciting.

If you can't make it splutter at WOT its not safe to open up. Wait until all the other stuff is done and save the piston.

Just as a quick reminder, this is my wife's bike. I'm just the grunt on this project.
At most she'll do sustained 4k rpm's in central California hills. Most all other rides will be stop and go here.

That being said, I want to see what this can do

Thanks again. Very much appreciated.

Break-in ride. It doesn't have 5 miles in that video.

Yeah I try not to treat it like crap for at least 100 mi. And a bunch of heat cycles.

But it makes me wonder when I watch videos on YouTube like those white one racing guys who are building and rebuilding engines to race right away and how they probably aren't running them in for hundreds of miles before a race. I wonder how many miles they are running them in first, and if not much I'm sure their jetting is spot on which prevents any premature damage!

They probably do like three heat cycles, a couple test laps, change the oil and call it ready. I think it's the official Malossi break-in guidance that says three heat cycles and go thrash.

Breaking in a motor is about making sure the rings are bedded and washing any leftover swarf and debris from rough edges that needed to wear down a little out of the transmission, which is why you were supposed to change the oil after the first 500 miles.

And Ray8, I'd say getting the jetting right is even more important since this is your wife's bike, even if she's mostly going to cruise along at the low end of the power band. After all, if anything happens while she's riding, not only will you have to fix it, but you'll never hear the end of it either.

I was thinking the same thing, especially if it's lean somewhere down low and seized up at 20 mph. Save a piston jet rich.