Modern Vespa

Hi all. I'm pretty new to the the forum and would love some advice. I recently purchased a 05 Stella 150 that had some high mileage and I'm completely going through it and decided to kit it out a bit. I've got a 166, race crank, 26/26, expansion pipe, and all new bearings, reinforced clutch, etc. etc.

I've matched the cases to the 166, matched the new carb through the reed area (cutting out the bar), and now I'm cleaning up the ports on the cylinder. Everything is going well. I'm planning on polishing the exhaust port to a nice finish.

My question: how polished should the surfaces be on the cases and intake side? I've read a lot on the web and get mixed options. They are currently very smooth, almost polished, but then I hit them by hand with 80 grit to leave small scratches in the surface (as I read on some forum). Is it worth it to find a small bead blaster and put back that sand blasted finish?

Thanks in advance!

On Modern Vespa, I would suggest that you post on the "Not-so-modern" forum due to the similarity between the Stella and the Vespa PX. If you haven't found it yet, you will also want to post on the Stella Forum on the Modern Buddy site.

http://www.modernbuddy.com/forum/forum14.html?sid=c51773f03a6565d704fc874eadbf6d41

Deleted, thought it was a economy 166 for some reason. I was incorrect!

You may not want to get quite this aggressive, but check out what blake7even did along those same lines.

Check out his Vespa Sprint "Sleeper" build thread.

I did a similar build on an LML motor I bought off scoot.net and converted it to 8" for my VBB over the winter. It's fun, but still nothing compared to my actual Stella, which is currently running a BGM 177 and a lot more go-fast parts.

A 166 kit -I assume Malossi ? or u get the cheapo indian stockish one ? THe Malossi is a fine piece of work and WILL work fine with a LML. As far as the carb make sure to match the whole intake (bolt carb and airbox together and match it )to the new carb opening and open and smooth the area under the reed block to allow for greater passage of air or Keaton is right. I ran a modified 24/24 and it was fine. Also if u remove the bar in the reed block you need to get other reeds and the stock ones won't work. I recommend the GGR hot reeds , they have lasted great in my similar engine. I am not sure about the crank but if you are doing a good kit then the stock crank CAN be a liability - ask me how I know ... so as long as its compatible (ie crank made for reed) my opinion is you did good. I had my stock crank reworked by HRA and it screams~ On the clutch rebuild with Honda cr80 corks -there's a thread here describes what to do. My basket held up - but I think its not a bad idea to band it or get a stronger basket. I did eventually put a Cosa clutch in mine to be safe. Oh and make sure if its a Malossi kit that you are timed to 18 degrees btdc. Jet it fat for break in and don't add extra oil to gas mix- I use crappy 2T oil for break in and I vary throttle constantly and don't rev it too hard. Also make sure your ports are chamfered in the cylinder - a sharp port can grab a ring or other nasty stuff! Good luck !

P.S. -check this guys youtube channel - he has several vids on gettign the goods from a LML. > https://www.youtube.com/channel/UCGFRPquIoR18LObBAcAoJZg

Thanks Falcon. Yeah I have a Malossi 166, Mazzuchelli race cut crank, Boyesen reeds, PipeDesign Voyager 177 exhaust, and reinforced clutch basket for the build.

I did actually bolt together the reed block, carb, and carb housing and opened/ matched the passage. I spent most of the day working on the jug cleaning up the transfers and polishing the exhaust port along with chamfering the ports. Since this is my first "tuned" scooter, I'm sure it's going to take some time getting the jetting correct for my build/ altitude/ etc.

My main question though is how polished should my case ports be? I've read both arguments and it seems that most people leave them with some texture, but smooth. Is it worth the time to bead blast them?

Thanks for the break-in advice!

You really wanted a flowed or bell crank to go with the reed.

I stared with a Worb5 flowed crank from SIP on the advice of Rob Hodge. Good value-for-money, too.

And I agree that the 26/26 will be too much carb. You'll never get it dialed in. I run a 24/24 with my Malossi 166 and am happy with it, though.

The texture of the ports is not anywhere near as important as the timing of when they open. This does change from engine to engine. Same cylinder put on either of two engines will have different timings on each one. This is one of the major reasons seemingly identical engines perform differently. If you are interested in power, then adjusting the port timing of your 166 is top of your list.

This I disagree with if the intake is opened -which he says it is - and good reeds are in place AND he has a badass expansion chamber - my dream pipe. Many ppl run 28mm modern carbs with this setup which is bigger still no ...? I am one of them .. I have a phbl 28 mm on mine with JL right hand exhaust.

I think follow what Jack has to say on the port issues -he seems to be scientist in this regard!~ On the jetting start with the tried an true combo of 55/160 pilot jet - 160 air corrector Be3 atomizer and I would guess around 135-145 main - I start hi as sputtering or 4 stroking doesn't hurt anything in the short term:)

Ask those guys at Pipe Designs about your set up. The Malossi is a common kit, they might have specific jetting, carb and port duration advice that would be VERY helpful. They know WAY more than anyone on here will. Do not bead blast the trans ports, just leave them a little rough. Most people didn't even respond to you're original question because the effect is mostly theoretical. Yeah, it creates surface turbulence and a boundary layer increasing air speeds... ahhh, or something...? But you have bigger fish to fry with sorting out your port durations and making sure the components play to the same tune.

Thanks for the jetting info. I'll take note of your suggestions for sure. I did consulate a shop that had built similar set-ups prior to putting together my parts list. Only one way to find out huh? Cheers-

Thanks for info. Yea, I already got a suggestion list from Marco at PipeDesigns. Those Germans are CRAZY for high performance scoots. Love it. Yea I just left the ports smooth but with texture. I don't mind putting in the time to make the ports "ideal" but I guess there comes a time when it's time to "move on" w the build to the next steps. Like building the motor up! Hope it runs.. haha

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Shiny exhaust ports delay the sooty coating but not that much, The non-polished surface on the intakes increases heat transfer so helps vaporise the fuel more.

BigD, did you work out what port timings the 166 cylinder has on your engine? And then what did Pipe Design advise you to set it to?

I wouldn't have paid for a 26/26 carb for this set up but as you have it, got better reeds and have matched it , when set up well it will perfom better than a 24/24. Be sure to drill the float bowl to 1.8mm, stock they are 1.6mm and this can cause issues (by issues I mean catastrophic damage) on engines with higher power.

For the sake of discussion. This is what the website recommends. I assume these timings and hp numbers are based on using a 60mm crank.

"The Voyager 177 works great on the plugged Pinasco Vespone cylinder on a rotary valve and diaphragm base (122 ° / 171 °). Then depending on the engine about 20 - 25 hp. If you optimize the cylinder slightly to about 120 ° / 174 °, you are at 24-27 hp and this engine already over 30 Nm"

You can drive and tune the Voyager on such a motor example:
- Pinasco Vespone cylinder (or similar) unprocessed
- 60mm rotary valve crankshaft
- 24 or 26 SI carburetor
- 21/68, 22/68, 21/65, 22/65
- PK XL2 fan or similar with 19 °"

Hey Jack, can you tell me a little more about drilling out the float bowl? I might have read this somewhere on a thread a while back but I"m not sure what this procedure does for performance or how to do it. I'll give it a go once I understand more about it. Thanks!

Oh yea, Marco from PipeDesigns gave me some guidelines on timing etc.

Want to share his suggestions for others? Advice from a pipe manufacturer is probably worth more than other more general suggestions. Nice project.

more important than fiddling with the ports on the barrel with the malossi 166 is opening up the piston.

there are three holes above the pin. these get opened up. the two on the sides of the middle one, more into slots.

there is also a lip on the bottom of the side cutout that gets removed. look at the attached picture and you should be able to figgure it out.

and second, a 24 or 26 is overkill, and harder to dial in on these than the 20 even with 'improved reeds' the reeds jus tare not physically large enough to flow enough at wide open to not be a restriction. Keep in mind, even when modified with the largest reeds you can on the stock block they still have half as much open area as a stock ET2 50cc, but with two 90 degree turns added in to the inlet tract to boot.

done the math, had it on a dyno, etc.

if you really want to go fast on an LML case, you need to look at side draft, RZ reed based setups.

My understanding is that the fuel tends to stick to the very smooth surfaces, and that a rough or dimpled surface causes a boundary layer... so the gas stays in suspension.
Of course if you choose one or the other you will never know the difference. But it's a lot less work to leave it rough.

That's my understanding as well... Hence why golf balls fly as they do (ie straight up, then veer dramatically to th left) & cricket balls are far better when used with sandpaper

Hey chandlerman.

I wanted to reach out since you've seemed to have a similar build as my 05 Stella and I have a question about squish.

I've been really busy with porting and working on the piston and everything is coming together nicely. I have my new bearings in and the Mazzuchelli race cut crank installed. I've done a dry fit with the cases and crank installing the top end to check the squish. I've torqued down the top end with the thin base gasket and the malossi o-ring on the head. I got 1.53 for squish with some fat solder. This is my first tuned scooter and I'm was wondering if I should take some off the head to bring it down closer to 1.1 or so. I have a nice flat grinding stone and I think I could remove just enough to bring it down and also use the o-ring since the grove is pretty deep for the ring.

Any thoughts would be appreciated.

Cheers-
Daryl

Before you worry too much about squish, you need to measure your port timings, as PureDrivenSnow pointed out. Once you have that figured out, you'll know where you need to shave down.

On both my LML motors, the casing's faces are really a millimeter or two too high, so I run with the thinnest base gasket I can get in order to get the port timings I need. I thought I was going to need to get a little bit of the face milled off or lap it down with a junk cylinder for my BGM build, but the timings worked for a box exhaust.

If you do need to cut down the top, I would not recommend lapping down the malossi head, though. I have a Malossi head that I lapped down half a millimeter and the o-ring tended to pinch and leak as a result.

Instead, assuming you needed to shave the top of the jug, I'd lap the top of the cylinder down to get squish to an even millimeter and no more than 1.2mm.

I run mine without a base gasket to get the squish I wanted (about 1.1-1.2mm)- I used spray on copper sealant to feel safe -no leaks and it liked it much more than with the gasket. I admit I didn't measure timings, just an experiment to play with squish that I feel was successful. One day I'll get with the cool kids and learn how to check the timings ...

I'm going to delve into the depth of porting. Not Vespa Suzuki 125 Trail bike.

What rotary tools and burrs are you guys using?

Dremel? Extra long shaft burrs? How long?

I've played with 4 stroke but access was easier and I used a 1/4 inch collet die grinder.

I use a dremel with a flex shaft. The flex shaft was a recent acquisition, but I'm a huge convert now that I've ported a barrel with it versus using the Dremel directly, I'll never go back.

For bits, I buy cheap bit sets off Amazon. $10 or so delivered via Prime, which makes them a tiny fraction of the price of name-brand, e.g. Dremel, bits and I'm still on the first set, though I just ordered more.

Past that, it's not into the details of how aggressively you want to port.

You'll probably want to add meat to your cases. Weld on aluminum if you have the means. Otherwise, JBWeld works just fine provided you are diligent with your surface prep. You want to maintain at least a 3-4mm flange between the cases and spacers or the cylinder.

When porting, be sure to match all the components so it's a smooth flow through all the bits. This means tearing the motor down once you know your spacers & port timings so you can stack it all together and then to final fit & polish on each side of the case individually.

Past that, I'd say take a look at my "Porting 101" thread, which produced a 16hp DR 177 despite me not really knowing what I was doing or Blake7Even's "Vespa Sprint Sleeper" thread, which produced something even beefier, I suspect, with a Malossi 166.

OK cheers I just want to clean out all the rough stuff (nothing radical) and to match the transfers to the crankcase etc.. to make it all smooth. I'm living in a company apartment so not much scope for major work.