Modern Vespa

That does sound like a pain. My Stella has a hole in the fork tube lower, and upper section I fished the wire through.

I didn't have an issue running the SIP speedo cable. Although take that with a grain of salt because I put it in there too soon and then when dropping the headset down I lost the cable into the fork.... so I tried to pull it up with some needle nose pliers and broke the plastic connection piece... so had to order a new one.

Running the actual cable wasn't too bad though. Just fish a cable from the bottom up to the top then before you pull that wire through tape the speedo to it and send her up! The second bend in the fork was the only dicey spot. I just pushed from the bottom and pulled from the top gently till it made it's way through. Maybe took 15 seconds there.

Well Rocket is home in his own garage. It's been a great journey with lots of good conversation, laughs, a few oh shits and many muffins and gallons of coffee consumed. Looking forward to many miles at home and on the coast with Scott as we dial these little beasts in. Thanks for all the help from you guys at MV that weighed in on our project.

Well, Rocket went home today....sniff......

It was inevitable, but still, B-62 is now a bit bummed.

We had another day of jetting today. Crazy what runs the best. I've got two pages of one line notes of the changes we've made.

I was trying to emulate some of you guys here that take astoundingly clear and concise notes - you know who you are. But even my chicken scratch and half-ass attempt came in handy in this jetting scene.

Turns out with the work we did on the engines (Slight opening of the rotary on both ends, and flow the inlet with the carb and box), the 20/20 carb, timing at 18~19 degrees, Pinasco 2-port 177 kit, and the sexy flowed Pinasco crank, the jetting turned out the smoothest at: 160/BE3/116 with 45/140 idle

I tried the 140/BE4/116 (122 bogged slightly at WOT) but couldn't clean up the mid range. I tried a 120AC, 160AC, with the BE4, the BE5, and the 120 & 140 AC, then put in the BE3 and wow, better. Then the 160AC and even better.

And this is all with messing with AF screw between 1 1/2 to 3 1/2 turns out for a variety of pilot jets. I've been dinking with this for weeks, on and off.

The 45/140 works best 2 1/2 turns out but still isn't perfect. I wanna try the 50/160 but don't have one (yet).

I don't understand why the 160/BE3 works better than the 140/BE4, except that it feels more responsive and just "better". I'll put a CHT gauge on next to ensure I don't blow it up, and keep a close eye on the plug, which looks nice so far.

Chris is going to take it easy on Rocket for the next several hundred miles (which should be ridden in the next couple weeks, knowing him), and also install a CHT gauge. He bought me one too, so thanks man! Oh, and Rocket has a 118 main jet just cause. Oh and both have B7HS plugs.

So it was a momentous day. A momentous day indeed. Both engines rebuilt. Both scooters back on the road. The culmination of many good days, good rides, good stories, good coffee, good friends. And I've got to thank all of you - for all the encouragement, advice, knowledge, skill, and help. It was valuable to us and to these wonderful little machines. Without all of you, this all would probably have turned out very differently (think piles of parts!). Thanks again!

Life is good

Lookin good guys!

Thanks guys... it's been fun following your progress!

First class write up qa ... we laughed, we cried ... really liked the pics too. The real story here is about spending quality time doing things you enjoy with a good friend. Cheers brothers!

Lots and lots of "dig it" in this thread.
Thanks for taking the time!

Awesome sauce qa and scootnewb goes to show the value of modern vespa and the sharing of knowledge that goes on here that leads to awesome posts like this.

Don't tell me that it's over, qa. It's too good to end.....(small tear)

Thanks for the awesome buddy posts and for keeping all of us entertained, some of us living vicariously, and most of us craving hot coffee and sweet treats.

For some reason, the Byrds are singing in my head....

(the turn, turn, turn is your wrench, of course )

And I imagine the story continues, because I must have missed the part where you simultaneously hit 60 on 8's....

Congrats on your raging success!

The best projects are like that when they have to end, and end as well as your well told tale has.

BTW, a shout out to Chris for knowing how to lash these things down properly!

Oh this story is far from over we're just starting chapter two the fun part, dialing these little beasts in. Summer is coming to the Oregon coast and I plan on devouring more muffins, coffee and getting plenty of that salt air. We've had great fun comparing them to each other and discussing differences like three speed vs four. It's nice to have a base to know if certain changes really made a difference or if it's like when your high school car gets a hole in the muffler and all of a sudden you just know it's faster. 😄

I was one of three scooters to do our local Distinguished Gentlemen's Ride in Eugene. I had three motorcyclists after the ride tell me how much they enjoyed the smell of my two stroke exhaust. How sweet it is 😄

Hey Scott I had no idea these two builds were going on or ida tagged along for the ride. Really well documented and although it took me a couple hours of reading got through to the end. I have learned to have Chris's idea , it's all a journey , no rush , enjoy.
Going back to read some stuff I skipped way to fast over.

Very Distinguished Chris!!

I took a little trip down the coast in the SS Minnow (97 Winnebago Adventurer) for some close to home exploring, and beach lounging, and just got back to the forum.

Thank you all for following along. Yes, We'll be updating with some cool pics of summer rides, and when we get the jetting sorted.... This pretty much nailed it - thanks for summing it and following along! Thanks K! Heh, heh. You WILL see that post, but it hasn't happened yet because the engines (Rocket's anyway) are too new to push it to 60. But when it happens....Wooohooo! ) And the seasons do Turn, turn, turn....Dangit - now that song is in my head!

Here are some pics of the southern Oregon Coast....

Hey JeTI-Jack! I've got a couple of questions (and anybody else, please chime in).

I finally FINALLY, did what you advised, which is run it with a 140/BE5/??? until it splutters at WOT in 2nd (it's a 3 speed).

122 MJ - definite splutter. 120 MJ - ever so slightly splutter, and only at the very top. 118 - clean.

So I put in a 115 and am calling it good! Now for the questions: I felt like I couldn't ask anything until I, at least, followed your recommendation.

1/4 splutter or stutter - I cannot get rid of it by swapping idle jets. I've tried lean 40/130, to rich 48/140. also 45/140 and 38/120. Each with 1.5 to 2.5 turns out, incrementally. It always stutters between 1/4 and 3/8. I even just held it on a quarter throttle to see if it'd clear or not. It didn't.

Any ideas of what to try next? BE4?, 120AC?, 160AC?, BE3?

To refresh your memory:
VNB2
Pinasco 177 2-port kit with Pinasco performance crank (57mm)
Dellorto 20/20 with float bowl passage drilled to 2.0 mm
Mild case work opening up the input both directions and flowing carb and box to case.
Vape static ignition, timed at 18 degrees.

Any and all advice would be greatly appreciated!

55/160 or 52/140 idle. Try a be1 or be3 as well. Low end sputter could also be the main is still slightly rich. If you just cleared up the top end range with main going down, it can still be affecting below the top quarter range for a few more jet sizes. What's the plug color at wot?

Good you took out the AC160. That was going to cause problems. When it gets fully hot like when cruising for hours at speed it will need the 118 main jet. If it runs clean at normal riding, I would put it back in for now.

Most rich feeling is actually lean. Hardly anything between how they bog except the sound. As Swiss said go richer. About 48/140 is the leanest. Getting the mixture screw set at or close to 2.5 turns for newer spaco is important.

Thank you Swiss and Jack. Jack, you mention the Spaco carb. This an old Dellorto carb, so 1 1/2 turns out?

And if the 48/140 doesn't clear it up, should I go with a BE4 mixer? or a 120AC? or both?

Thanks for the help guys!

Scott - try advancing your timing a degree or two. 18° static may be too delayed to allow smooth combustion at that critical transition between the idle and main.

I'm at 20° on my GL with a similar set up (Pinasco alu 2-port, SIP Road 2, 20/20, moderate porting, cut crank). I'm running 140AC BE3 114 with a 48/160 idle and it pushes through that 1/4-1/2 throttle with no stutter or stumble at all.

Worth a try. Listen for pinking at WOT of course ... but I don't think you'll get any.

Thank you SCG! I'm going to give it a try tomorrow - I'll let you know how it goes...

Turns out I was actually timed at 24 degrees! I changed it to 20 degrees and put in the 140 AC.

This whole time I've been thinking I've got a Dellorto carb in there - It's a Spaco, so my fiddling with the AF screw has been, well, screwed. I need to be out 2.5 turns, so I need to try 2, 2.5 and 3 to see what's what.

Crazy thing is the best it's run is:
30/120 idle (super lean) with 140/BE3/112. But still a slight hiccup at 1/4 throttle. I keep thinking maybe go with a richer mixer (BE5), then I can go with a richer Idle jet. Logic sounds backwards though....

Umm that's a bit off in the timing. Isn't Spaco stamped on your carb? I had been reading Jacks method for setting up for the correct idle jet, turning out 5 and turning in until the highest of revs on tick over and if it doesn't land at 2.5 turns it's the incorrect idlejet ( don't quote me in that just spewing this before having to run out the door to work) did you attempt to figure the squish yet?

Yep I thought all my carbs were Dellorto. That's what I get for thinkin....

I checked the squish also. Ready for this? 2.8mm.

I have some solder that is 1.5mm thick, but couldn't get it to read by the spark plug hole, so I twisted a triple chunk of it and taped it to the piston. Yes, I pulled the head. It was bugging me. So I've got a .25 base gasket, and a 1mm rim on the head alone.

So I can lap the head down 1mm, or close to it, and swap out the base gasket with...gasketseal...

Or I can put it back together and not worry about it. I'm getting tired of dinking with it. I think I'm going to email Pinasco and ask them about this kit and see what they have to say about squish and jetting.

The squish on my 2-port Pinasco 177 was stupid-big. I'd have to dig back through my last rebuild thread to see where it started, but I ultimately wound up using a 60mm crank, in part to get the squish down.

I like the way you tackled the undetermined squish problem. I also got 2.8mm on my squish test. Before bothering Jack any more I need to get a bgm or vmc head which is supposed to take up the excess clearance. I'm really in no rush , from here on in it will be more about the journey, I'm quite intrigued by these Spaco carbs and how they function. Until I get a head I'm going to see if I can dial things back a bit and do some seat of the pants tuning, really I'm not looking to have a rocket but more of a dependable smooth running 40 to 60 mph cruiser.
Scott I realize now what the different atomizers do , owing the amount of air/fuel ratio from low end to high end , hopefully I understand that right. Scott have you received knowledge as to the difference between a 160 ac and a 140 ac?

160 is larger than 140 so it lets more air in. Main reason for changing the air correctors, at least how it makes sense to me, is to allow you to control the size of the main jet as desired. So if you are using a small main jet but you want a slightly larger one to provide more fuel flow onto the piston for cooling, you go up to larger air corrector but keep the same ratio of ac to main jet size which gives you the same air fuel ratio but with more air and more fuel due to larger sizes of the subsequent jets. I have been doing the opposite, using too large main jets, so been going to smaller air correctors to bring my main jet size down.

example:

You are using 120/be3/105 main stack and it's the correct jetting, but you want to use a larger main jet cause your kit calls for something like a 115mj. 120/105 = 1.14 a/f ratio.

Switch to 140 ac, take the a/f ratio and figure out the corresponding new mj by 2-1.14=0.85 then 0.85*140=119. So your new main stack is 140/be3/119 and it is equivalent to 120/be3/105. 119 main lets quite a bit more fuel in than a 105. More fuel = more cooling, but the ratio is the same so the jetting should work equally.

There seems to be other reasons for using different air correctors based on what works well or bad with the cylinder size and or idle jets. That i'm not too sure about.

Thanks CM1 - it's stupid-big for sure. At this point I'm going to "make it work". We'll see how that works out Thanks Lynn - 2.8 for you too? Interesting... I'll be watching to see what you do with the head. I may spend an afternoon and lap the head - one of these days when my plate is empty. Yeah, right, like THAT ever happens... Thanks for this Swiss! I've been assuming that was the gig, so it's nice to hear it spelled out. I know there is overlap with the mixer tubes in the mix, or it'd be super easy. I'm starting to get the pressure thing with the mixer tubes after 50 or so different combinations of AC/mixer/MJ & Idle jet. Oh, lets not forget the AF mix screw. And I haven't even looked at the slide...

I'm going to try some things tomorrow, now that I know that the squish is cavernous. I cannot help to think that Pinasco did this for a reason. It'd be nice if they shared why this is on their product details area. Maybe it was designed from the get-go to have a 60mm crank? I would've ordered one if that was the case.

But I digress - I'm going to try some things tomorrow, and we'll see how it goes!

Trying my darnedest to follow what you're saying, where does the 2 in 2-1.14=0.85 come from?
Honestly I had no idea that the ac divided by mj gave the afr.

Its been a while since I did math cause I went to school for art.. but I'm sure there is probably a better equation to get the desired results.. I just subtract the ratio by 2 so I can get the inverse which is what you need to multiply the air corrector by to get your desired variable, because you know what AC you want to go to.. you do not know what main jet is the equivalent, this is the variable you are trying to arrive at. If you knew what mj you wanted to go to, and you were looking for the equivalent air corrector, you would just multiply the new mj by the a/f ratio directly, instead of subtracting it from 2. In the example I gave, the ac is larger than the mj.. so you can't multiply the new AC by the a/f ratio itself cause its larger than 1 and you would end up with a larger mj than air corrector... so you need the inverse to get the correct mj which is smaller than the ac.

And when I say a/f ratio.. I mean the discrete a/f ratio of the main stack itself 160(air)/be3/125(fuel), hence a/f ratio (of the main stack itself) 160/125=1.28. Same can be figured out for the idle jet which is both the air corrector and fuel jet in one.. 55/160... 160(air)/55(fuel)=2.90 a/f ratio of that specific idle jet. Neither of these give you the a/f ratio of the whole carb, but just the discrete ratio for each stack individually. I assume you would get the global a/f ratio from a sensor in the exhaust... like how they do it on a dyno.

Again, this is how I understand all this stuff, coming from someone who sucked at math in school. For all you smarterer guys, I apologize for my crude path to get there.

EDIT: I guess the correct way of getting the inverse is 1/n instead of 2-n because my way only works when the number is smaller than 2.

Ok now I get it , it just depends which one you are after as to multiply or divide by 2.
I new about the idle to get the afr but did t realize it was the same for the stack. Now is it not true that the tops of both the idle jet and the stack or ac work in unison the same as the bottoms of both do?
Scott I hope you don't mind this carrying on , I'm hoping it will help both of us and others in the long run.

Don't sweat the big squish. It's not the reason the engine sputters at 1/4 throttle. Vespers came from the factory with squish in the 3mm + range.

The reason the squish is big is because Pinasco built the kit primarily for use with a 60mm crank. A 60mm crank sits level with the top of the cylinder at TDC. All of the squish is in the head. That's what the 1 mm "lip" is for.

The bigger squish with 57 mm cranks isn't a problem per se. The only downside to big squish is slightly less efficiency and slightly less power. That 1/4 throttle sputter is all timing and jetting.

If you want to reduce the squish don't mill the head. What you want to do is take 2 mm off the base of the cylinder.

My poor math has led you astray.

using my crappy method on the example I gave.. you would only do 2-1.14=0.86 and 0.86*140 to get the main jet. If you started with the main jet and wanted to find the air corrector, you would do 1.14*desired constant main jet = air corrector.

I feel I'm digging myself in a hole here!

BTW, I apologize for sidetracking this thread.. I thought I was on lynnb's thread.

Excellent, thanks! I'm running your setup tomorrow - one of the scenarios I want to try out! Thanks again! No way Lynn - this is awesome. I'm glad it's being discussed here - I was just thinking it would be awesome to have this all in one place, but hey, half the fun is getting to see all the cool stuff everyone is doing!

And thanks again Swiss for doing the math - cause we all love doing math so much

I too think you have a 60mm kit. 3mm squish is going to run, obviously. Will just be down on power and prone to detonation when driven hard.
If you keep it like this, higher ignition timing will help with the lower compression. As SoCal sail, especially evident at lower rpm.
The carb will adjust but will need to be done again when the squish is sorted out.

Missed this post, good information, food for thought for sure.

More interesting then welding machines - but I do miss the coffee and donuts.

Seems a couple of you guys have the giant squish situation.

Scott - are you unhappy with how our girl is running?

Not giant but yes large, but what SoCal said made pretty good sense.

You crack me up CM2 - Coffee and Donuts this Saturday - hopefully the weather won't be too rainy, cause we plan doing another tuning session.

So here is the skinny: They both run amazing strong, and plenty of torque and top end speed. Super fun and crazy for such a little thing.

BUT - I cannot get rid of the 1/4 throttle splutter or stutter. I've tried a bazillion combinations (OK, only 50 or so, written down) of idle jets and main jet stacks to alleviate this issue.

I've taken and tried everyone's advice. A few issues I ran into:

1) I thought I was timed at 18 degrees BTDC. I was actually at 24. Now I'm at 21.

2) I thought I had a Dellorto carb, which meant 1 1/2 turns out. Wrong, I have a Spaco in there. Just a boneheaded maneuver on my part.

So now I'm trying a different approach: I've got a 160/BE4/122 main stack, and the plug looks good and it runs solid - and fast.

A new shipment of idle jets just came in this week (thanks to Chris), and I have a bit more variety to play with, vs just the 4 I was using before.

Now I need time to try various idle jets and play with the AF mixture screw on each one and see which one works the best. However close it gets, that'll be the way I'll run it. Then I'll install the CHT gauge (and 23 tooth clutch).

Chris has been running the CHT guage and has the exact same build, so whatever the VNB2 (B-62) ends up with, the VNB5 (Rocket) will get too.

Bottom line is when I'm cruising through town at 30 to 40 mph, at 1/4 throttle, I don't want to have to constantly drop the throttle to nothing, then up to half or 3/4, then nothing, repeat... I should...SHOULD...be able to cruise along at 1/4 throttle without it gurgling along.

Yes, I'm on a mission...

Any advice? I'm willing to try anything, but I'm not shaving 2mm off the base of the cylinder. It has plenty of power for my scene. I'd just like it to not gurgle at 1/4 throttle.

BUT, it this is as good as it gets, it's pretty flippin awesome!