Modern Vespa

Swiss, my $.02.
That plug pic is great! - and by that I mean - your photography is really solid.
The plug itself is another story.
That color you show - in daylight - is the color I get when I am 1 size jet off the rich/safe size I need. Really close.

In short - you gotta move from that color to something that resembles brown - but it happens at this point often with a single jet size.
You can run like you have it - no problem - other than a bit of fuel consumption and smoke - but the next step should give you that BaWAAAAA! sound that will bring great pleasure.

Keep in mind - I have no formal training - am willing to take unreasonable risks - and offered advice on my second posting when I didn't even know what a two stroke was. (Ginch has reminded me). Just sayin.

-CM

I do think a hone and new rings would probably be smart, although I'm going to wait a while as it is running great and I just spent 1 1/2-2 years breaking stuff and rebuilding it multiple times over. I kinda just want to ride it for a while before I start tearing it apart again! Surprisingly it doesn't seem like its lost much compression from the soft seize. I do keep meaning to do a compression test when its warmed up to see how the rings are holding up though. Yes I do feel like it is 1 or 2 points too rich and think I could sneak it a bit closer as there is still just the slightest richness right at the crossover for idle and mj. Although that may just be a fine tuning of the air mix screw which I will do next time I get a chance. For the first time I am seeing the rough texture buildup on the plug that looks to be from the right jetting/temp.

I was contemplating reaming out my 122MJ to a 124 or 123 to see if I can get it just right, cause the thought of jumping 3 points down from 125 I think might be too much.

And I am not looking to trash it again by going too far. I've spent enough money on this scooter! Need to earn its keep by giving me a couple years of fun before I contemplate putting a bunch more money into it!

My next step would be 120MJ. Need to be sure this is 120 relative to the 125 in there at the moment.

If I were you I would buy a new box set of main jets. These are generally incremental. Sizes may not be exact but they are relative to each other.

If that plug was taken from WOT runs when fully thash hot, then it might go down even further. Don't be scared by running weak, there is a long way from a bit lean to seize up. When lean it starts to lose power and sound rough first. If you feel this don't ride hard....for long. They are tougher than you think.

SIP is very adamant on their website that their own brand main jets are bang on the sizes that are stamped on the jets. In fact they use their accuracy as a differentiator.

I have gotten almost all of my jets from sip, but incrementally not as a pack. Swa, i thought the same too from their descriptor they brag about the accuracy. So i am skeptical of my measurements. But i will say that their jets are occasionally differently manufactured. Some jets are more fancily manufactured by sip with the numbers laser etched in the side, others are more old school manufactured with the numbers physically stamped on the side. So this makes me question their accuracy at least between the two different sip manufactured styles. I hope that the laser etched jets are newer and more accurately manufactured, but when ordering piecemeal one can never tell which version of sip jets one will get! That plug photo is definitely not thrash hot wot. It was after 15 miles of holding mid throttle high rpm in low gear, then a very quick wot run of less than 3 seconds.

If this plug was just from a fast cruise kind of rpm, then you really could go down 5 points. Plug is still black, with crusty black bits. This is an over rich plug. Do the same again with a 120MJ (relative to the 125MJ). Plug should be the only thing that's a shade of brown after that run.

Two different types of sip jets. And unfortunately they mix and match right at the sizes i need them to be consistent.

All below are sip jets

135-stamped
132-laser
130-laser
128-laser
125-stamped
122-stamped
120-stamped.

I've ordered new 122 and 124 so i will see which those are.

Still on same jetting. 120/be5/125.

Hard wot run for little over quarter mile pinned in 2nd. Probably about 7-10 seconds held pinned.

Temps are close but still in 3rd and 4th at wot they slowly going up around 350.

Hoping that is just from slightly rich jetting and a minor timing adjustment to bring it down into good range.

Are we still talking about scooters?

Well here's some sound porn for you questionable viewers. Sorry, no video.. cellphone was stuffed in my hoodie underneath my jacket to muffle the sound a bit.

Most of this is in 2nd gear held around quarter throttle cause I was stuck behind a slowpoke going between 30-40mph in 2nd gear almost the whole time. But it helps to exaggerate the slight stutter at the crossover of quarter throttle. And at the 120/be5/125 mj pictured above.

https://www.youtube.com/watch?v=As0DegDDfGU

and here is some video for those who like to see/hear it. Some slight smoke on revving.

Went down to 120/BE5/122 MJ and it runs great but still with the slightest stutter at 1/4 throttle. I also fine tune adjusted the air mix screw finally. I'm now at 2.75 full turns out on the 160/45 idle. I could get it to stall out when closing down the screw on the last half turn. Couldn't get it to stall out when opening up to 10 half turns out although it felt like it was getting close to stalling at that point. I didn't want to open it any further out of fear it would pop out the hole. Didn't want to take carb out to reseat that screw!

https://www.youtube.com/watch?v=misxYCTtBmU

I'm done messing with this for a week or so.. my neighbors are sick of hearing this! I'll put at least 100 miles on this and check plug again before going to 120 if needed.

Think it's rich at higher rpm but lean at 1/4. Sounds weak as rpm falls and rich again at tickover. Keep with that 122MJ but change to a BE4. Check WOT again, as the BE4 will be richer. Then check 1/4 out on the road. Must be getting cold out there.

Hibbert and I were just discussing the 1/4 throttle does seem lean. It got better when I went richer on the air mix screw. He and I were wondering if the idle was too lean, but as you said, it seems rich at idle. I was also conflicted because the plug looks rich when idling and it smokes a bit, but the 1/4 throttle stutter was confusing me.

Lucky I have a be4 on hand. In fact, I think this kit came with the be4 atomizer.. so they may have known what they were doing when they included it!

Yes, it is getting cold. This past week has been probably some of the last warmer days I was able to get out and do some jetting and riding, although I have been wearing thermals and winter riding gloves on the colder days. This week has been in the high 40's to mid 50s and that's why i've put some time into messing with the scoot. That and my large sip order for the p200 hadn't shipped for days.. so I am on hold with the p200 engine.

Hahahaha.
Swiss - sounding good!
Interested to see if Jack’s solution gives that nice return to idle.
Seems like a good one.

Good to see u back on the road with this!

Just looked at my mileage records on this 1st OS piston/rebore. I've put 550 miles on it so far including the soft seize somewhere in those 550 miles. Trying to get about 60+ miles on every jetting change over the past week. For a small island.. this means driving around the same roads a few times.. probably annoying the crap out of everyone around those routes with my preference for high rpm 2nd gear!


I would go for a nice long ride tomorrow, but it's gonna rain all day and these SIP performer tires suck in the rain!

Ha! I find a big wave and a smile will (usually) get them to wave back and smile after about the 3rd or 4th pass.

Left it at 122mj and switched to BE4. It was a decent improvement! Still the slightest stutter either at 1/4 or below 1/4 throttle. But it is greatly reduced and much cleaner at 1/4 throttle when held at mid to high rpm than on the BE5 atomizer! Plug photos are not after the hot WOT run, but after 20 miles of mid to high rpm quarter throttle driving.

Compression tested after a hard run and I'm at meh 100psi when engine is hot. So maybe I should hone and replace rings. I think I will have Lee at that scooter shop do this when I head down to florida, since the cylinder doesn't need replacing and the jetting is close. I wanted to make sure I stopped into his shop to have him look over and tweak anything that needs it. Would like to give him what little business I can on the way through Georgia.

Also got a cheapo faux gopro on amazon in June to use on this scooter and never pulled it out of the box. I threw it on the crash bars today and shot video of the temp gauge for you guys to see what the temps do based on throttle/rpm.

CHT is on the right. EGT is on the left.

CHT yellow range is 250-350F
EGT yellow range is 1000-1200F.

First video is of a 2nd gear WOT run for quarter mile. That run is the first 50 seconds of the video. It felt a little flat/rich when it hit wot and pinged up at the max rpm for a few seconds.

https://www.youtube.com/watch?v=x9Z9wR9yP_E

Second video is a longer vid of my typical city street driving which shows a more accurate view of normal temp ranges at mid throttle, high rpm.

https://www.youtube.com/watch?v=BiWDJ5IGWo0


120/BE4/122 MJ. 160/45 Idle. 2.75 turns out a/f screw.

120/BE4/122 MJ. 160/45 Idle. 2.75 turns out a/f screw.

120/BE4/122 MJ. 160/45 Idle. 2.75 turns out a/f screw.

120/BE4/122 MJ. 160/45 Idle. 2.75 turns out a/f screw.

120/BE4/122 MJ. 160/45 Idle. 2.75 turns out a/f screw.

Closer jetting.. and the burn pattern is getting better on the piston crown.

Good progress. Plug now actually a shade of brown. Looks like you are in good company with the thinking 4 stroking feeling was rich but in fact lean.
Continuing on theme. Its most likely your plot jet is lean too. Piston is a long way from black. The one colour you don't want to see on a piston is silver................. black, very dark grey or gold are the only acceptable colours.
On the pilot jet the 45 part is most likely near correct. Just the air number to vary. 45/120 would be something normal to see with a BE4.
Once the turkey is all gone it might be time to wake up the neighbourhood.

Tested this 45/120 yesterday and it was much improved but still slightest stutter down low. Almost nearly there! Gonna try out my 48/100 and 50/120 as Jack suggested to see how they differ, but expecting I'll have to drill the 48/100 to make it a 48/120.

He also mentioned reed pedal thicknesses which got me out measuring the thickness of my boyesen reeds. The outer thicker one is 0.72mm, the inner one is 0.39mm. Was contemplating cutting my own reed pedal from malossi reed sheets or other, but they only sell in thinner increments... 0.30, 0.35, 0.40 mm. I'm curious to try thicker and thinner pedals to see how it affects the performance.

I also removed the curved metal backing plate when upgrading to boyesen. After watching a bunch of videos on reed pedals I'm wondering if i should bring that curved metal plate back into the equation to act as a stop for their max opening.

Swiss - nice work. Looks like you have gotten your hands around the jetting and moved on to other tuning tricks. Ha!

So what are the tradeoffs of thicker vs thinner reeds?

I wouldn't say ive got my hands around jetting.. but it is finally starting to click on a rudimentary level. Thanks to much hand holding. It helps when Jack gets you to within striking distance so that you can finally hear/feel the correct jetting. Bike really does get quieter and smoother when its nearly dialed in. Holding mid throttle at 50mph and it just sings and feels smooth, almost like you aren't going that fast.

But now I'm over rich on the idle with a 48/100 as it wants to stall from being too rich when idling and bubbles a bit when accelerating from stop. Which in fact really helped keep temps down and feels so much better with high rpm when rolling on and off throttle. The bike just feels stronger when on the main jet now.

Funny story.. I got stuck in left lane at front of red light today when left lane was a left turn onto highway and I wanted to be in right lane. I gunned it when light changed to beat the guy next to me so I could get over quick before the turn as he had a huge line behind him. Didn't realize it as I was glancing over my shoulder to make sure I had room to change lanes.. and as I looked back ahead of me, I realized I was doing a wheelie through the intersection while in the middle of changing lanes with all the cars stopped at the intersection looking at me like WTF is that vespa doing! That isn't an uncommon sight in my neighborhood for swarms of kids on dirtbikes to be doing wheelies down the middle of the road, but I'm sure its the first time anyone around here has seen a vespa doing it! That was purely from the extra grunt the no longer lean idle gave it.

Time to drill the 48/100 to 48/120. Hopefully I have a 1.2mm bit in the garage.

Regarding reed thickness.. Jack was suggesting moving away from the boyesen 2 stage reeds I'm using now and cutting my own from malossi reed sheets. As far as I gather from what he's mentioned to me.. thinner reeds = faster throttle response. Thicker reeds are better for higher RPM bikes than what we are dealing with even on our tuned engines. Which now that he says that.. makes me wonder if the boyesen reeds are actually restricting flow, cause they are two stage with the 1st smaller stage being 0.4mm thick and the larger 2nd stage being 0.75mm thick. And if he's right that a 0.75mm thick reed pedal needs over 10,000 rpm performance, that would mean I'm using less than half the reed plate opening 100% of the time! So cutting my own pedal is on the agenda once I get the material. This also makes me think that I'm going to have to change jetting around a bit if the boyesen reeds really are restricting my airflow.

Depending on your drill bit set, looks like there are a few options. You could try one of the smaller ones and work your way up. That's what I did when I was working on a custom jet.

This set looks like it has 5 sizes you can try on your way to 1.2mm. Amazon has a few smaller less expensive sets also.

https://www.harborfreight.com/titanium-m2-high-speed-steel-drill-bit-set-115-pc-61543.html


https://www.google.com/url?q=https://www.fastenermart.com/files/drill-size-chart.pdf&sa=U&ved=2ahUKEwijvcG07abtAhWRZzABHSw_DSQQFjAQegQIBhAB&usg=AOvVaw3XhrV1_rRwVBrU3dZaqUwt

Odds are I might already have the right sized bits. I think I bought a few around that size when drilling the carb. If not, I'll take a chance on something like what you suggest. Thanks Christopher!

Just in case I bought these not to expensive and free shipping with prime. I bought both the bits sets due to reviews of inaccurate sizes. Measured them all before use to verify sizes.

The black plastic box had duplicates of the same bits, I did find enough to experiment. I was using a 160/? (40 - ?) at the time, easier for me to use a 160 / 40 and work my way up to what I wanted. Only changing one variable that way.


https://www.amazon.com/dp/B01MS1CNLV/ref=cm_sw_r_cp_apa_fabc_6o8WFbJ1R47VX

The bits with the colored plastic markers were all correct sizes.

https://www.amazon.com/dp/B088GWR3N8/ref=cm_sw_r_cp_apa_fabc_-q8WFb17JFTSD

I had a 1.20mm manual drill bit so I was able to drill out the 48/100 to 48/120. Its almost spot on now! Still the slightest stutter on the idle jet, and plug looks a bit rich. Took it for a longer ride after the plug photos and I think the temps when held at WOT in 4th go up around 350F but dont seem to climb over that. I got it up to about 68-70mph before I backed off.

Outta town this week so outta time to mess with it until next week. I still need to go richer on main to find the bubbly point again.

sounds for you guys again.
https://youtu.be/Ar6FUSlEoRk

Put about 40 more miles on it after these plug photos and took a look again. Its dark chocolate but definitely brown color now. I think it might be able to go down to 118 or 116 pushing it. Currently still at 122. Will do more tests in morning before I head out of town for the next week.


manual drilling the idle.

48/120 idle. 120/be4/122 MJ

that bike sounds so good!

Got back from out of town last night and got done with work early today so i got out on bike and worked on jetting again. Went up to 128 and it was hard to start kept flooding the plug. Ran with no or minimal bubbling at top end in second once warmed up but it was pretty bubbly at first. Also once warmed up on 128 it felt a little slow top end to get up there.

So i went down one size from the previous plug photo of 122 to a 120. It might be right here or maybe just maybe get down to 118. I'm gonna ride it like this for a while and put a fresh plug in before i even consider making another mj change lower. Plus the piston photo looks like it's correct for what Jack says it should look like. Carbon deposits all the way to just before the transfer ports on the sides. Only thing I'm not sure about is the piston seems a bit clean up near the boost port. That may just need more miles though. I think I'm gonna start messing with the air fuel screw on the idle to see if i can clean up the four stroking that occurs below quarter throttle.

Btw it's too damn cold to be riding this now. I would still ride but i haven't found winter riding gloves that keep fingers warm enough while also not interfering with using the controls. After about 30 miles i was done cause the finger tips were getting frosty. Eventually plan on getting heated gloves but not right now.

Also too damn cold to work on bikes in the garage. So progress will be slow for the next few months.


120/be4/120











Boost port

Took front hub off to start balancing tires and am wondering if i should replace the front brake disc. It's grooved. Not deeply grooved but enough i can feel them when running finger tip over it. Disc is 3.88mm thick.

Front brake pads also need replacing. 2280 miles on these brake pads.

I hope you don't mind me saying but I think you're chasing your tail a little bit here.
I've had 40+ P/T5 Vespas since 1980 and I have kitted every one of them, some with blistering performance and some a bit meh...
The ones I've left with a standard carb I've only ever changed the main jet starting at way too rich and working down until it stops bogging at WOT.
Never had a seize or other problem from that though I have had the usual problems from air leaks to intermittently leaking seals, etc..
On the other hand some of the carbs I've had on my Lammys I'll not even put a MJ in until the idle circuit is dialled in, I am no expert I just follow instructions metculously! Certainly not a SI carb expert but never had a problem getting them to work well.
I do tend to always ride at WOT so that works for me and if you're like me just put the rest of the carb back to standard with a big MJ and work down. If you mainly not thrashing the lungs off it I'd have it on a dyno.
Please don't take this as a knock, just some thoughts that may help.

No problem. I agree I'm chasing my tail for months. But I have had multiple seizes and its finally dialed in almost perfect. Temps seem to be where they need to be and just need to get enough courage to get back on the highway and test it out longer rides.

What I would try next is to get the bogging fixed. Remove the extra float gaskets. Put in a BE5 and get WOT to flood. If 128 is near rich, then 120 is too low. If WOT is not correct the rest will never dial in.

Hate riding mine in heavy gloves but it's the only way this time of year.

On hold due to weather..

Wasn't expecting this today!

2-3 week hiatus due to snow on ground for most of that time after an 8-10" snowstorm, and about 3 weeks of sub 40 temps mostly around 30F.

Front tire/hub balanced, new front rotor disc/brake pads.. everything up front smooth as butter.

Finally removed the extra float bowl gaskets.. back down to 1 gasket normal float height. Didn't bother removing the reed block to replace with custom cut reed yet. Worked incrementally up starting at 120/BE4/132 to 140. 132 and 135 gave slightest rich bog at the transition of quarter throttle. 138 gave a bit more but everything so far was still clean at WOT and once it broke through quarter throttle rpms. 140 MJ is the mark it finally felt boggy through most of the higher throttle ranges. So I think my richness mark to work down from is 135/138. I swapped in a 130 MJ to get home and I am very happy with the feel/sound of the bike. It is cleanest throughout full throttle range that I've felt since starting to tune the bike. It also sounds smoother and quieter. Im happy at 120/BE4/130 MJ and 48/120 for a while. Will leave it there and run a ton of miles onto it and a new plug, keeping an eye on the temps at wot. Maybe even get it back onto highway finally and see what it does up at the higher end finally.

Christmas miracle!

Merry Christmas ya filthy animals!

I just came across this thread. Same replacement FA Italia input shaft problem. And the problem was that I bought it from SIP.

The broken one is a Piaggio shaft. The new one is a FA.

The primary gear wasn’t spinning correctly on the shaft, so out comes the calipers...

The input shaft is worthless to me with that tapered bearing surface. I’d like to return (or exchange) it out for a different one, but I think I’m just screwed again from SIP.

Trying to understand what you are showing. The fa italia input shaft has needle recess which is turned down to 11.5 at the top and bottom of the recess, and 11.6 for the meat of the middle of the recess? Messaging the bearings don't fit. Why would they do that?

You might be able to take it to a friend with a lathe and bring it all to the 11.5 thickness?

I wish i had measured the recess thickness on both my lml and p2 input shaft when i had them both out.

It's a bad angle of my first pic of the caliper measurement. I'm actually measuring from the bottom of the recess in that picture, NOT midway on the shaft.

The top of the resess has been turned down to 11.5 while the bottom has been turned down to 11.6. So when the primary gear spins on the input shaft, it tried to spit the gear off the end of the shaft. A slight taper is all it takes to mess up something expensive inside the engine!

Does that clear it up?

Got it. So there is a taper to the recess which obviously is gonna f up the functionality of the needle bearings.