Stella 2T highway/performance upgrades
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Tue Jul 09, 2019 8:29 am quote
Swiss - Uve done some brave tuning - and been kind enough to post detailed results - even when imperfect... made the rest of us noobs smarter. Thanks.

Keep it comming!
Molto Verboso
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Tue Jul 09, 2019 9:02 am quote
charlieman22 wrote:
Swiss - Uve done some brave tuning - and been kind enough to post detailed results - even when imperfect... made the rest of us noobs smarter. Thanks.

Keep it comming!
I second this! Thank you!!!!
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Tue Jul 09, 2019 12:16 pm quote
SoCalGuy wrote:
Holy crap swiss... my 2 cents... you took that poor top end right to the edge running WOT with that dinky main jet and no air filter. You could’ve taken one for the team in a big way. Unless you’re deliberately trying to seize, you need to be at least up in the 120 range. FWIW, when I ran a bellmouth on my 20/20 (Polini 177) I used a 125 main.
What air corrector were you at? Rotary valve engine?

I guess you can call me evel knievel! They say ignorance is bliss and that is true. I was not as nervous going 69 mph with those temps as I probably should have been. I did have a worry though with those temps and sounds so I was hesitant enough to back off when it was apparent there was no limit to temps rising. I've seen a lot of threads here mention safe temps in either the 2-300 range or the 400 range so the 360-70 i was getting into got my cautious mind thinking maybe I should ease off! Fingers remained on the clutch the whole time in anticipation!

Charlie and qa.. Glad I could be of service. Hopefully I won't be the test pilot for everyone's enjoyment soon! Would love to lock down the Jetting and stop messing with it sometime soon. Waiting to lock it down before I commit to daily commute by highway.
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Tue Jul 09, 2019 12:24 pm quote
Jack221 wrote:
Wow. You were lucky. I can't believe you didn't feel it.

Edit. btw if that didn't seize up nothing will when down at 320F. Running in is officially over. Yay
I'm gonna assume this thing won't seize cause I screwed up the chamfer and rehoned it probably too much to fix the nick in the wall, plus I went a little wider on the ring gapping. Add on your extra rich idle jet 45/120 and all those things saved me!

With that said, I'm more ok now than before with an extra noisy cylinder if that's the up side!

I'll be back out there narrowing it down from 118 mj in about 30 min.
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Tue Jul 09, 2019 2:01 pm quote
Switched to 52/140 idle jet again. This cleared up sluggish takeoffs from stop. Started off at 120/be4/118 MJ and worked down to 108MJ without taking it off center stand or putting carb lid back on. Just worked it down until revving on stand could get over 8000 RPM, which was at the 108/109 mark. I don't have a 109 MJ so I went from 110 to 108. I'm gonna go take it for a WOT plug/temp check now. I can already see from a couple miles driving that it wants to cool off when I give it a bunch of throttle.

One thing I will say so far is that it is a lot less rattly now. Seems to have quieted down in mid throttle compared to before the 92 MJ fiasco. It seems to have broken it in!

If it never gets to 320F at 108MJ I will work slowly down until it gets close then do a plug check and report back.
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Tue Jul 09, 2019 2:26 pm quote
Swiss 1939,..
A local saying from where I'm from could be used for one of your recent test runs,..
Your maize !!! 😁 Lol ,..
pek
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Tue Jul 09, 2019 4:10 pm quote
Quote:
What air corrector were you at? Rotary valve engine?
160AC, BE3 atomizer. 48/160 idle. Rotary. Put hundreds of miles on it, long, long stretches at WOT, no issues.
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Tue Jul 09, 2019 5:53 pm quote
Spent 3-4 hrs riding around my highway loop back and forth stopping at each end to make adjustments to jets and carb settings trying to dial this thing in. I am still not quite there yet, but I feel like the last 4 hrs I've learned more about jetting than all the time leading up to this.

Some observations and thoughts:

A.) really helpful to tell me that 320F is the target temp for MJ at WOT.

B.) It's really important to have some known constants when trying to figure out jetting, cause you can achieve a good spark plug color a million different incorrect ways, but there is only one good way.

This reminds me of the quote of Edison that Ben Gates quotes in the movie National Treasure (yeah ive seen it a million times):
"You know, Thomas Edison tried and failed nearly 2,000 times to develop the carbonized cotton-thread filament for the incandescent light bulb. And when asked about it, he said 'I didn't fail; I found out 2,000 ways how not to make a light bulb,' but he only needed one way to make it work."

C.) I am assuming these are my constants: 320F at WOT for correct MJ, and 52/140 idle jet at 1.5-2 full turns out air mix screw.

Here are the results of my incomplete jetting experiments tonight:

1.) I went from 118 down to 108 based solely on max RPM on center stand with the goal to get over 8000 RPM.

2.) After my first highway run I realized that 108 was too lean as it wanted to go over 320F.

3.) I spent the next hour or so making trips back and forth on that highway loop stopping at each end to make adjustments in response to temps.

4.) I worked backwards to what is commonly accepted safe practices and worked back up to 116MJ making a jump of 2 sizes after each run starting from 108.

5.) I think 116 might still be too lean as it was still getting up in the 310-320 range and climbing on my last run when I was not holding WOT the whole time, but oscillating between 3/4 throttle and full throttle about every 15 seconds.

6.) my last plug check immediately after WOT run was at 114 MJ and it looked nice as the color of milk chocolate, but the temps were still climbing past 320F so I went to 116.

7.) I did not check the plug immediately after 116 WOT run but waited 10 miles of middle throttle city riding till I got home. When I got home the plug check was super rich around the edges but dark chocolate on the very tip.

8.) I think my MJ can still go up, but the rich plug is a result of incorrectly set air mix screw.

9.) I kept 52/140 idle the whole time and there were drastic responses to each MJ change.. it got really boggy in low to mid throttle once I started going up from 108MJ which I started to figure out I could control it by really making drastic changes to the idle screw (throttle stop screw) which would let me move the correct air mix settings in or out based on my idle screw settings.

So why did I initially get better results on center stand at 108 MJ but then work back up to 116 when under load? I think it is a result of a combination of throttle screw and air mix settings being off. All of this leads me to a realization/hypothesis which I will move to my next post as it really should be a separate item that I have questions to anyone following along with this process.

Last edited by swiss1939 on Tue Jul 09, 2019 6:52 pm; edited 2 times in total
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Tue Jul 09, 2019 6:46 pm quote
What I noticed with my jetting experiment is that the throttle set screw really makes a difference with the idle rich or leanness. This in turn really affects the plug check that can throw you off if basing jetting solely on plug color.

My experience was as following.. I felt this whole time my idle jet was too rich even when it was actually too lean because my air mix screw settings are constantly really small approximately around the 1 full turn out range.. sometimes 1.5-1.75 full turns out, sometimes less than 1 full turn out. Assuming this was a result of a really rich main jet bleeding into the idle circuit and thus throwing off the results, so I would go down on main and thus be able to use a larger idle jet and open up the air mix screw wider. But, since the main jet temps are too high at WOT, I realized I needed to go larger on main jet, which would then force my air mix screw settings to get smaller to keep it from dying at idle. This led to frustration and confusion as to why my air mix settings are too small and or why my idle jet seems too rich.

Since I know that 52/140 and 1.5-2 full turns out should be a constant with this kit due to the instructions (as jack says a 45/120 idle may actually be correct, but since they are so close, im gonna pretend that isn't true temporarily and keep 52/140 as the constant for now just to have a constant). I realized in all this that when I went up main jet, i couldn't get it started or keep it running at idle, until i turned the throttle screw in, thus widening the throttle slide opening at idle. So knowing that a 52/140 idle should be correct, but my current air mix screw settings were too small, and I was getting bogging at low throttle, I decided to make some adjustments to the throttle set screw (idle screw) to see if I could move the air mix screw settings closer to ideal and hopefully fix the bogging issue at low throttle.

I began to turn the throttle set screw in, closing it further, and widening the throttle slide opening in the venturi tube. This would raise the idle which I would counteract by turning the air mix screw out, enriching the idle mix and lowering the rpm at idle. I never fully got it to 2 full turns out, or fully dialed in the main jet, but I believe that I am working in the right direction. Temps were going down at WOT and seemed to be less of a temp swing when city driving. The only thing I can't account for yet is why the plug is so rich.

My observation about this whole concept of throttle set screw adjusting the throttle opening in the venturi tube and its relation to the air mix screw leads to these beliefs for now:

1A.) the more you close the throttle set screw and thus open the throttle slide at idle, the more gas you add to the idle.

1B.) To counteract the extra gas at idle, you open the air mix screw, making the idle more rich.

1C.) in this way you can have an idle that seems set correctly in that it idles properly and settles properly from throttle down but leads to a mixture (air mix setting) that is too rich if you adjust it too far.

2A.) the more you open the throttle set screw and thus close the throttle slide at idle, the less gas you add to the idle.

2B.) To counteract the less gas at idle, you close the air mix screw, making the idle less rich.

2C.) in this way you can have an idle that seems set correctly in that it idles properly and settles properly from throttle down but leads to a mixture (air mix setting) that is too lean if you adjust it too far.

So my question to anyone more knowledgeable that is following along is whether my observations are correct? And if so, what is the correct throttle screw position to set it at before adjusting air mix? Which brings my observations full circle back to the idea that it is really important to have some known constants when setting up a carb.

I feel like I saw somewhere that said the throttle slide should be set at a certain width opened by default at the start of jetting/carb tuning but I cannot find it anywhere right now.

si2020carb_throttleScrew_1.jpg
going too far this way leads to a too rich idle when set correctly where ever that air mix setting rests?

si2020carb_throttleScrew_2.jpg
going too far this way leads to a too lean idle when set correctly where ever that air mix setting rests?

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Tue Jul 09, 2019 7:54 pm quote
Be careful out there cowboy.

0CEE5AF2-C7BC-4752-BB64-00DD3F563C31.jpeg

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Tue Jul 09, 2019 8:01 pm quote
PureDrivenSnow wrote:
Be careful out there cowboy.
Lol. yeah. You live and you learn. I won't make that mistake twice.
Molto Verboso
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Tue Jul 09, 2019 11:56 pm quote
You've been busy.

The first limit is aim for 300F max for a 1 mile 4th gear WOT run. This is then the main jet done for now. Something like 120AC BE4 115MJ should be this.

Next get the pilot. The limit is the transition cough at 1/4. 45/120 should be correct. 52/140 will be the same but mixture screw will end up further in.

Mixture screw. I thought you were having trouble. Its not easy and you're in good company. If you wind the tickover screw in until you have a 2000rpm tickover, setting the mixture screw gets a lot easier. Start adjustment with 2000rpm and the mixture screw 6 whole turns out.

Run with no filter for now and buy yourself a Vortex once you go 24/24.
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Wed Jul 10, 2019 1:46 pm quote
Jack221 wrote:
You've been busy.

The first limit is aim for 300F max for a 1 mile 4th gear WOT run. This is then the main jet done for now. Something like 120AC BE4 115MJ should be this.
120 AC BE4 116 MJ is still reaching higher than 320F. I will keep going up.

No work on either scooter project today as the headliner in my truck that has been sagging in front of the rear window for 2 1/2 yrs finally fell down completely blocking the window this past holiday weekend while I was visiting family. Had to pull it all off to get back from New England. What a mess that crappy gooey sticky foam made as I was driving. Today was my first full day off since, so I had to remove the fiberglass headliner and clean the truck up. I bought the replacement foam backed fabric 2 christmas' ago but never bothered to do the repair cause I didn't want to deal with it until absolutely necessary. Just happens to be the hottest damn day of the year I had to finally deal with it.

Regardless, I will be purchasing the gravity fed spray guy qa has been using on his allstate project today.

https://www.amazon.com/gp/product/B0046RDW3K/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

I was waiting for more of a reason to buy it than one project and here it is. I'll use it for the contact cement to repair the headliner fabric in my truck, and when I'm done with that I can use it to paint my p200 project inside and out with por-15 2k urethane top coat and any other painting needed for that project!

IMG_20190710_152442.jpg

IMG_20190710_160838.jpg

IMG_20190710_160853.jpg

Molto Verboso
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Wed Jul 10, 2019 5:13 pm quote
Right on! The compressor I use is an old Craftsman 30 gallon 220 belt driven thing I bought for $20. It needed some cleanup and a new regulator, but it pumps for about 15 seconds and I get massive spray time out of it.

I think with your 10 gallon you'll be fine. You may need to wait for it to recharge, but it's not like you're painting a car or anything, and you can take a break with the glue you're spraying. And you'll get a feel on how much air the gun takes in relation to your compressor, before you start spraying the scooter.
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Wed Jul 10, 2019 5:25 pm quote
qascooter wrote:
Right on! The compressor I use is an old Craftsman 30 gallon 220 belt driven thing I bought for $20. It needed some cleanup and a new regulator, but it pumps for about 15 seconds and I get massive spray time out of it.

I think with your 10 gallon you'll be fine. You may need to wait for it to recharge, but it's not like you're painting a car or anything, and you can take a break with the glue you're spraying. And you'll get a feel on how much air the gun takes in relation to your compressor, before you start spraying the scooter.
Mine is the 10 gal tank. It doesn't like constant flow tools like a grinder. It works but the compressor is constantly on. I'm gonna use the headliner as a test with the spray gun to see how much the it turns on to fill up during the spray. If it is constantly on I'm thinking I'll buy the 11 gal harbor freight aux tank and hook them up together to get 21 gal capacity for spraying. Just need a water filter.

I've used air gun to paint small things with good success enough times that I'm not worried about being able to paint with a larger gun. Art school has its occasional benefits.
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Wed Jul 10, 2019 7:29 pm quote
Swiss - since u took a night off jetting - thought I would post here some relevant own experience.
Since its closely relevant to your postings (and I promise there will be no discussion of welding) I thought this was a good spot for the convo.

Liked your "hold some constants" and Jack's 320 max rule of thumb - I put on my vortex/bellmouth and upjetted combining those two concepts.

BE3 160 AC.
Went from 102 mj to 118 and started walk down.

118 mj could barely break 200 degrees WOT.
115 mj same. Ac about 212 degrees.
112 mj will get to 245 in 4th at ~4200rpm but FALLS to about 230 at 6000rpm (4th gear wot will not top 4200rpm. 3rd will top out slightly over 6krpm)

112 feels slower at top speed than 115 mj. Wonder if I could be too lean.

So question to the crowd.
- If u can't reach 300 degrees, does that signal u r still too rich by definition?
- if 320 is the max u want to hit, is it best to just work down until u hit that temp before u even bother pulling ge plug to read it?

Interested to hear perspectives.
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Wed Jul 10, 2019 11:29 pm quote
First thing you do its a WOT plug chop. Way too rich or way too lean could cause this.
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Thu Jul 11, 2019 12:55 am quote
Thanks Jack.

Seems like u might burn thru a few plugs to find the range?

Curious - Are there others less destructive means to get in the starting range then a destructive test like the chop?

Swiss - I believe ur starting point was suggested by the manufacturer. Did you do an actual cut of the plug?
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Thu Jul 11, 2019 4:49 am quote
Not chopping the plug. Just running 10+ miles for city driving or as long as I can for WOT then pulling the plug and looking at the color.
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Thu Jul 11, 2019 6:25 am quote
Jack221 wrote:
Mixture screw. I thought you were having trouble. Its not easy and you're in good company. If you wind the tickover screw in until you have a 2000rpm tickover, setting the mixture screw gets a lot easier. Start adjustment with 2000rpm and the mixture screw 6 whole turns out.
Jack, I'm not having problems making the air mix screw adjustments. I'm setting it exactly how you describe, turning rpm up to 2000 then adjusting until the point it starts to increase. My problem is that when I set it correctly, the screw position is under 1.5 full turns when the idle jet is correct as you and instructions state and all mention of correct air mix position is that it should be between 2-4 full turns out.

I'm back at it all day today.
Molto Verboso
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Thu Jul 11, 2019 6:25 am quote
Yeah, actual plug chopping of the plug is just for race bikes and people with really bad OCD.

For our needs if you can see there is a pale brown ring at the bottom and a pale brown ring at the top leaving a white band in the middle, that's plenty close enough.

Chances are yours is totally white (hopefully without silver) or black.
Molto Verboso
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Thu Jul 11, 2019 6:29 am quote
swiss1939 wrote:
My problem is that when I set it correctly, the screw position is under 1.5 full turns when the idle jet is correct as you and instructions state and all mention of correct air mix position is that it should be between 2-4 full turns out.

I'm back at it all day today.
Correct is 2.5 whole turns. Slightly less like 2.25 turns is ideal when not stock.

At 1.5 you're not that far out. What pilot jet is in there? How does 1/4 throttle feel?
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Thu Jul 11, 2019 7:23 am quote
charlieman22 wrote:
Curious - Are there others less destructive means to get in the starting range then a destructive test like the chop?
Yes. I like oopsclunkthud’s method (actually what Gordon Jennings recommends)

1. Put a jet in it that is so large that it won’t run at WOT.
2. Work your way down until it doesn't bog.

That's it. You are now about 95% to perfect jetting and on the rich/safe side.

You can then spend as much time as you want murdering plugs trying to achieve that last 5% of perfection.
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Thu Jul 11, 2019 10:27 am quote
Jack221 wrote:
swiss1939 wrote:
My problem is that when I set it correctly, the screw position is under 1.5 full turns when the idle jet is correct as you and instructions state and all mention of correct air mix position is that it should be between 2-4 full turns out.

I'm back at it all day today.
Correct is 2.5 whole turns. Slightly less like 2.25 turns is ideal when not stock.

At 1.5 you're not that far out. What pilot jet is in there? How does 1/4 throttle feel?
I had 52/140 in all last time jetting and all today jetting. I finally found the second dip you mentioned. What I did was turn the idle screw all the way in which opens the throttle stop all the way open to raise the idle as high as it will go. Then I turned out the air mix screw all the way to 6 full turns out. Then walked it back half a turn at a time. Finally noticed that there is a small increase in idle at about 4-5 half turns out, or 2-2.5 full turns out. This is separate from the second increased idle where the engine starts to race. I feel more confused then ever now about jetting after today. Here is my results today stopping due to rain.

I put 122 main jet in and it ran horrible throughout. Went down to 120. Same thing. Went down to 119 seemed to clear up only after 5000 rpm but super bogging everything below and plug check was blackish with white hints on tip. So I went back down to 116 then went on my highway run. Plug check is nice milk chocolate but the temps are over 330 so I went up to 118. Highway run again temps still around 320. Boggy as shit below 5000 rpm. I gotta gun it really high rpm to clear it up before changing gears or it just bogs to a crawl. I'm thinking main jet is somewhere around 117-120 based on wot temps.

My problem is that with those mj and a 52/140 idle, everything below 5000rpm is terrible bogging. I took a shot thinking maybe it's the opposite of what I always assume and it's a lean idle. So I went to the 45/120 idle Jack suggested and it got worse. Plug check after middle throttle riding home is extremely black rich plug.

I know you keep saying 45/120 or 52/140 idle is where I should be at but with so much bogging mid throttle... that has to mean idle is too rich if my mj cannot go any lower due to wot temp limit. It only got worse when I went from 52/140 to 45/120.

I keep thinking I'm getting closer and starting to understand it but the more I mess with it trying to get the constants to work, the worse it gets and the less sure I am about jetting as a whole.
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Thu Jul 11, 2019 10:48 am quote
Here are my thoughts about where to go next with this jetting. Due to horrible mid throttle bogging when idle jet set to correct as instructions, and mj set to keep wot temps as close to 320 as I can get right now, I feel there are two options:

1.) Change the atomizer from be4 as instructed/included by kit. I have a be1 and a be3. Comparing them all the be3 and be1 have additional holes closest to the air corrector that be4 doesn't have. Be3's additional holes are larger than be1. I have a chart from this site that says what each one does to the main vs idle. Be1 doesn't look much different than be4 on that chart. Be3 looks to even out everything on the chart. I'm thinking be3 with larger holes would lean out mid throttle bogging more than be1, so I should try be1 first as a smaller step then go to be3 if not enough cleared up.

2.) Go smaller on idle jet leaving atomizer the same.

I'm gonna try the atomizer changes first as the idle jet size should be an unchanging constant.
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Thu Jul 11, 2019 11:17 am quote
Be1 did nothing to clear up bogging. Trying be3 now.

Also, since removing filter completely, I get a lot of fuel on top of the carb lid around the summer plug which is still in. The back of the carb is also very wet.

IMG_20190711_114547.jpg
Back of carb is very wet without air filter. Blowback? Reed pedal issue? Or just cause no air filter?

IMG_20190711_114539.jpg

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Thu Jul 11, 2019 11:37 am quote
Be3 did nothing to clear up bogging. I'm guessing if I were to run with the be3, then I would probably need to come down on the main jet a few points as now with that be3 it bogs all the way up and wont get over 6000RPM in any gear.

I literally cannot make the malossi instructed idle (52/140) or the suggested richer idle (45/120) work with the main jet when keeping the WOT temps under 320. Messing with these richer idle jets only makes the scoot run like absolute crap, and spending days in the heat messing with it as it runs worse only has me walking away and not wanting to touch my scoot for the next couple of days.

Last edited by swiss1939 on Thu Jul 11, 2019 11:58 am; edited 2 times in total
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Thu Jul 11, 2019 11:54 am quote
Why are you running a 120 AC ?
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Thu Jul 11, 2019 11:56 am quote
SoCalGuy wrote:
Why are you running a 120 AC ?
I was at the stella stock 140AC but went down to 120AC on Jacks suggestion because he was saying the stella reed engine demands less air than the rotary engine vespa.
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Thu Jul 11, 2019 1:01 pm quote
Have you checked the condition of the reeds?
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Thu Jul 11, 2019 1:18 pm quote
SoCalGuy wrote:
Have you checked the condition of the reeds?
I was thinking of doing that, maybe next week. I need a few days away from the scoot.

I put those boyesen reeds in at 8150 miles. The scoot has approx 9870 miles now. Approximately 1700 miles on them. I thought they would be good till about 2500 miles, which is when I was planning on replacing them preventatively.
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Thu Jul 11, 2019 1:44 pm quote
Did you find out what main jet gets the WOT temperature down? And or WOT plug colour not black?

Edit: Remember these pilot jets (52/140) are for the Vespa not LML. The LML will need weaker which is why I said 45/120 but maybe you need less like 40/120
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Thu Jul 11, 2019 1:59 pm quote
Jack221 wrote:
Did you find out what main jet gets the WOT temperature down? And or WOT plug colour not black?

Edit: Remember these pilot jets (52/140) are for the Vespa not LML. The LML will need weaker which is why I said 45/120 but maybe you need less like 40/120
I did not yet because I was getting so much bogging I couldn't get to WOT on the highway. It has to be in the 117-122 range, but as I went up the bogging increased from the rich idle so I switched tracks and tried to deal with that instead of continuing up on the main. 45/120 is richer than 52/140. It ran so much better when I had both the 40/120 and 48/140 in on the low end.

I'll get to it sometime in the next week. I just need a break from messing with the scoot so intensely for the past two weeks. I'm burned out on jetting right now.
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1980 P200E project, 2005 Stella Malossi 166 MKIII
Joined: 20 Jul 2018
Posts: 858
Location: Staten Island, NY
Thu Jul 11, 2019 9:09 pm quote
Jack, you got me wondering about the correlation between quantity of supply vs richness in an idle jet, since you said the lml requires weaker idle but the 45/120 is technically richer.

Im thinking that means because the 45/120 pulls less air into the circuit than a 52/140 that it also provides less fuel to the circuit than a 52/140, albiet a more rich but smaller supply? Or does the qty of fuel being supplied through the circuit remain constant based on the vacuum demands of the cylinder?

I'm frustrated by the si carb but also can't stop thinking about or trying to understand technically what is going on and how it all works together. What effect does supply vs concentration of supply have on the engine and how the carb changes either of those elements.

If the AC in main jet and idle jet circuits really do affect quantity of fuel supply into the circuits then if you could pretend that the correct jetting for a generic engine could be found in a carb set up with 120 ac main and 45/120 idle circuits vs another one set up with the equivalent 140ac based main and 52/140 idle jets, then the 120ac carb would have better fuel economy even if the 45/120 idle is a slightly richer mix.
Molto Verboso
Joined: 26 Oct 2015
Posts: 1562

Thu Jul 11, 2019 10:05 pm quote
swiss1939 wrote:
Be1 did nothing to clear up bogging. Trying be3 now.

Also, since removing filter completely, I get a lot of fuel on top of the carb lid around the summer plug which is still in. The back of the carb is also very wet.
Things are going to get real wet when you don't run a filter. It's just the nature of the beast.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1359
Location: London UK
Thu Jul 11, 2019 11:28 pm quote
whodatschrome wrote:
swiss1939 wrote:
Be1 did nothing to clear up bogging. Trying be3 now.

Also, since removing filter completely, I get a lot of fuel on top of the carb lid around the summer plug which is still in. The back of the carb is also very wet.
Things are going to get real wet when you don't run a filter. It's just the nature of the beast.
exactly. The blowback is not trapped in the filter. Once jetted better it will reduce to the point it doesn't run down the back of the engine.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1359
Location: London UK
Thu Jul 11, 2019 11:36 pm quote
swiss1939 wrote:
I'm frustrated by the si carb but also can't stop thinking about or trying to understand technically what is going on and how it all works together. What effect does supply vs concentration of supply have on the engine and how the carb changes either of those elements.
If you just focus on one thing at a time it gets done much quicker.

Find out what main jet gives you good for now (brown) WOT plug colour.
The socalguy method is a reliable way to get near.

Forget about pilot jets and all the splutter until you get this done. If you can't get a brown plug at WOT something else is wrong.
Addicted
1980 P200E project, 2005 Stella Malossi 166 MKIII
Joined: 20 Jul 2018
Posts: 858
Location: Staten Island, NY
Sat Jul 13, 2019 4:41 pm quote
Ok. I've messed with jetting a little here and there the past couple of days trying not to get burned out on it. I am able to get a main jet that is chocolate and not black so there is no issue with that, but I did notice the rubber carb lid seal tore in the back from tightening it too much, which is probably why there is so much oil/gas spewing out onto the lid. I also had the cylinder cooling hood slightly off cause the spacer holding it to the stud came off which probably affected WOT temps previous to thursday. I fixed that before making tweaks here and there friday and saturday. Also ordered some extra carb box lid rubber from scooter mercato that will come next week.

I am also not gonna post as many individual posts about specific jetting numbers as I feel its making me second guess everything. I'll post something about it when I think im good.

I do want to pose some questions regarding the theory of jetting though that may help me narrow it down.

First question. When you say 300-320 F at WOT max, does that mean WOT all day if I held it for 10 miles or constantly for extended time it should never go over those temps.. or does that mean 300-320F for x number of miles/time of WOT?

Second question. When you get the main to the point where it is chocolate and not bogging throughout the whole throttle range, but the temperatures still go slightly over 320F, but going up main jet size introduces more bogging... can going down a main jet size in order to open up the air mix screw further enriching the idle circuit bring the WOT temps down by way of enrichening the idle and the main circuit?
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1359
Location: London UK
Sun Jul 14, 2019 12:15 am quote
Once you get the main jet at WOT to lighter brown thats the main jet done for the first pass.

As an example. If I cruise at 70mph with the odd pop over 80mph on the motorway to Brighton (25miles), my 221 will not go over 320F at any point of the journey. Usually holding about 295F steady.

When the plug is beige at WOT and you are sure the jetting is correct but the temperature will not stay down, then there must be another issue causing it. The issue will be at least one of the following suspects ; Spark plug number too big (cold), too much 2 stoke oil, too much ignition timing, too much trapped compression, bad head design, cooling issue or the worst of all, intermittant air leak. There are probably more but these are all I can think of this early on Sunday morning.
Addicted
1980 P200E project, 2005 Stella Malossi 166 MKIII
Joined: 20 Jul 2018
Posts: 858
Location: Staten Island, NY
Sun Jul 14, 2019 8:06 am quote
Jack221 wrote:
Once you get the main jet at WOT to lighter brown thats the main jet done for the first pass.

As an example. If I cruise at 70mph with the odd pop over 80mph on the motorway to Brighton (25miles), my 221 will not go over 320F at any point of the journey. Usually holding about 295F steady.

When the plug is beige at WOT and you are sure the jetting is correct but the temperature will not stay down, then there must be another issue causing it. The issue will be at least one of the following suspects ; Spark plug number too big (cold), too much 2 stoke oil, too much ignition timing, too much trapped compression, bad head design, cooling issue or the worst of all, intermittant air leak. There are probably more but these are all I can think of this early on Sunday morning.
Ok so a good rule is to find the good light chocolate plug at mj wot, and if temps still hot you can try to control wot temps by either retarding timing or going to colder plug.

I was just going through the Malossi instructions again double checking the plug temp guidelines. I have b8 plug in. I just noticed the instructions say to use b8 or a b9 under extreme use. So I will try a b9 plug first and if that doesn't do it I'll check timing again and potentially go to 17 degrees to see if that helps.
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