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Nedminder
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Never seen a 55/100 and BE4 not be rich enough low down.
?

Can you clarify (before I "discover" Latin America)?
Whats your point?
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Jet Eye Master
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The main jet is too small. 116 might feel good but it's too small. Find the WOT flood point again.
Careful not to end up in Egypt.....home of de Nile.
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Nedminder
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That was the nile?
Did seam a bit narrow.

I ran the 118's and saw fall off on power - this with the Be~5.
I'd have to go back and look - or re-run.
But I don't follow the logic.

My flat spot - "gulp" - was occurring at handoff between idle and main.
Motor loved when the main came on - bog was prior - in late part of 1/3 throttle.
To test - I started richening up the bottom:
- First with 55/100 - improved gulp and throttle response significantly.
- Then Be4 to nudge it a bit richer at handoff - improved gulp to all but gone.

Figured that BE4 might make it too rich through the middle and top - so I took main down - but it lost WOT power at higher RPM.
The Atomizer is really attacking the middle throttle area mainly.

So I could put larger main in - but prior experience showed that a power killer at WOT.

D'ya want me to run that again with the BE~5 and chart?
Or are you saying BE4 with richer main?
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America does have the most peculiar mountains
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Molto Verboso
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UTC quote
[quote="charlieman22"]
Quote:
Swa - will be interested to see what Knocks out your issue in the end.
Will be fun to apply an AF meter to mine to get some data as well.
-CM
I suspect mine will be less demanding to jet, given that it's a lowly (but mildly tweaked) DR177 compared to what you have. The BE5 is in, and it revs well on the stand, but then we had the mother of all rain storms, so didn't get to ride. Besides, my choice of idle jet is limited to those that end 160, several 45/140 and a 52/140 (richest one I have). If xx/120 is where I need to be, I'll need to to get ordering. I'll try the 52/140 for the hell of it.
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Nedminder
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I'll try the 52/140 for the hell of it.
Will be interested to see how it does for you.
I felt ridiculous putting the 55/100 in.
Who even has a 55/100?
Why do I have this in my collection?
Expected it to be one of those - out one side of the driveway and back in the other (this, sadly, is not an uncommon length of test ride for some of my efforts).
Started - no smoke.
But when I went to pull away - all power and crisp.
Caught me off guard.
Gulp minimized.

Jack - do you think I am so lean on main that I am effecting 1/8th throttle?
Easy enough to test - but I dont think so.
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Jet Eye Master
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Find the flood out point for AC120 BE5. This is where there is mild but obvious splutter at WOT. Two sizes down from that is correct, most of the time. Careful with your eclectic jet collection.

See how the max power is after that. If this is rubbish there is another way.

Now we know you have been struggling with a weak bottom end all this time, it all changes. Either the main jet is wrong or needs a change in direction.
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Molto Verboso
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Mine is definitely better with the BE5 as expected. The obvious 'cough' has gone, but it's still not totally clean at low throttle and through progression. However, 112 MJ is too small, as I cannot get the now famous 'splutter at WOT'. Going to try 120, then walk it down. I cannot see a DR177 needing more than 120/BE5/120
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Swa45, have to find the WOT flood out point. This goes for any carb on any 2 stroke. Just spluttering when it hits the highest rpm. I would expect this to be over 120. Once the main is set, atomiser, then pilot. After that back to WOT for the second round. Done like this in a few rounds it's properly done. No surprises and no trips to foreign lands.
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Nedminder
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Find the flood out point for AC120 BE5. This is where there is mild but obvious splutter at WOT. Two sizes down from that is correct, most of the time. Careful with your eclectic jet collection.

See how the max power is after that. If this is rubbish there is another way.
I can re-run - however - on past efforts:
- Was going down on power over 118
- Had flat spot you could land a helicopter on at hand off

Simple enough to plug back in and see.
Yes - not using that 120 that is smaller than my 112's!
Can use those reamers to ensure it is larger than 118 and smaller than 122 before inserting.
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Jack221 wrote:
Swa45, have to find the WOT flood out point. This goes for any carb on any 2 stroke. Just spluttering when it hits the highest rpm. I would expect this to be over 120. Once the main is set, atomiser, then pilot. After that back to WOT for the second round. Done like this in a few rounds it's properly done. No surprises and no trips to foreign lands.
I gotta do this with B-62 (Pinasco 177 2-port kit) before I end up shit creek without a paddle. Not a foreign land to me, but I don't want to go back there - again....
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Jet Eye Master
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charlieman22 wrote:
I can re-run - however - on past efforts:
- Was going down on power over 118
Try going through the motions as normal procedure and see where it ends up.

AC120 BE5 50/120 and main jet until it just floods out at max rpm. Drop two sizes then the rest is easy.
The fact you were having trouble getting the crown full black. And how it sounded on the WOT runs always made me feel it was lean. Getting this correct may be a small waste of time but once you feel it run correctly the SC jetting will be easier.
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qascooter wrote:
I gotta do this with B-62 (Pinasco 177 2-port kit) before I end up shit creek without a paddle. Not a foreign land to me, but I don't want to go back there - again....
I'll hopefully get back on my VBB tuning in a week or so. I'm stupid-busy into next week, then supposed to be riding all next weekend for Chicago's annual Slaughterhouse Rally (This year's theme: Socially Distant since 1996).

After that, though, I'll also be going through this same adventure with my 2-port Pinasco 177, too. We can compare notes
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No surprises and no trips to foreign lands.
If you don't go to Cairo - you won't have as broad a perspective.
But its always good to be home again.

Flopped my homemade BE~5 back in - and moved main jet well up - 123 and 125 for these two tests. Left the 55-100 idle in as it seems shockingly responsive at 1/8th throttle and was the largest contributor to knocking out the flat spot at hand off.

Results from the runs were - shall I say - surprising.
Nicely Jack.

Saw sustained speeds over 60 in 3rd - for first time ever - on speed runs.
New HP peak.
Will have to ride a bit to see how it feels all round - but fun has returned a bit.

120AC/BE~5/123 - or 125MJ. Very rich idle jet - 55-100.
Keep in mind this was with carb top off.
Expect some adjustment down in richness when top goes on.
Will be interested to see what this looks like on AF meter.
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Family wanted Pizza & Beer from the pub.
Wood fired oven - who can blame them.
Being the family man that I am - I "offered" to pick up.
Swapped in the richer 128MJ - did I mention the speed run is on the route to the pub?
You can see how I am organizing my life.
Results below.
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Good weekend everyone!
Good weekend everyone!
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Jet Eye Master
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Really was way under. Dyno shows 125 as the best. What was the flood out jet?
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charlieman22 wrote:
Family wanted Pizza & Beer from the pub.
Wood fired oven - who can blame them.
Being the family man that I am - I "offered" to pick up.
Swapped in the richer 128MJ - did I mention the speed run is on the route to the pub?
You can see how I am organizing my life.
Results below.
I like it, that diet Beer though, you need a Guinness or Left Hand Milk Stout. 😃
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Nedminder
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Really was way under. Dyno shows 125 as the best. What was the flood out jet?
I wold only know if I had fully followed your directions properly.
Which is to say - Im guessing 132/135 area.

I did take the time tho to sort and measure my jets.
That 120 that was really a 110-111 was the first jet I ran when I started to tune in - wouldn't fully rev out.
Then when I started walking down - felt stronger as I went.
Dyno'd better at 116 then 115 and 118 (as marked on jets I had) so thought I must be there.
Live and learn.

It's night and day now.
Not the syrupy smooth pleasure of the SC - but back to the raw power feel of a well tuned SI sitting right on top of the crankshaft.
Little shake and chatter out of the Super Strong clutch getting its ass whipped leaving the line.

AF meter arrives on Monday.
I will hold til then to both tune in the box top and find flood out jet.
I want to see where I am on the meter with this tune so I can understand where and how its affected when sealed box top goes on.

As you noted - this should be instructive for the SC.
The piston pics with wash on the piston were from there.
My impression was - it was too rich down at the bottom.
Will be interesting to go back to it with this tuning experiance under my belt.
Quote:
I like it, that diet Beer though, you need a Guinness or Left Hand Milk Stout. 😃
only when close to the source.
last piston top pic - from Smart Carb before the SI went back on
last piston top pic - from Smart Carb before the SI went back on
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Molto Verboso
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I love how this thread keeps resolving. (Fairly) instant gratification! You move so fast ;P

I feel like I've read mixed things about the use of exhaust meters on Vespas? Guess we'll find out soon enough. Just hope it doesn't send you down another rabbit hole... reckon you should trust the plug, piston crown and dyno over the AF meter until you are sure it is giving legit and useful data.

Eagerly waiting to see how it goes.
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I feel like I've read mixed things about the use of exhaust meters on Vespas? Guess we'll find out soon enough. Just hope it doesn't send you down another rabbit hole... reckon you should trust the plug, piston crown and dyno over the AF meter until you are sure it is giving legit and useful data.
Jetting is definitely a game of diagnosis.
Think of this like adding an Xray.
Might not show soft tissue - but you can still see bone on bone.

Speaking of which.
Last minute chance to meet friend out by the beach yesterday - so jumped on the scoot.
First long ride with SI carb.

The good: scoot runs cooler. Even on long pulls on the hwy.
Power ws good.

The annoying the hand off pause at 1/3 throttle. In the hills - under load - was exposed. Not nice in the middle of a sweeping corner going up an incline. I played with the idle mix screw between 2.5 and 1.5 turns but couldn't knock it out. Suppose I could have dialed it out to 3.5 to see if it got better or worse.

Jack - you wanna take another attack at this? I'm still waiting for my goodies from Smart Carb - and at this rate - I will end up having the SI factory tuned by the time it arrives.

I can richen up with atomizer a touch - coming down on my main. I am already at 55-100 on my idle. wadda you think/ what do I attack it with.

Edit* Below a couple pics. I plan to use the air fuel meter to get a read on what's going on with the different set ups. Perhaps will be able to tie back to some pics of pistons and or spark plugs.
Plug after 50 mile ride.  Looks nice - tho perhaps a little sooty around the outer ring suggesting rich idle.
Plug after 50 mile ride. Looks nice - tho perhaps a little sooty around the outer ring suggesting rich idle.
Piston after 50 mile ride.  Also looks nice.  Super rich wash from SC 1/4 throttle (I think) has started to fill in.
Piston after 50 mile ride. Also looks nice. Super rich wash from SC 1/4 throttle (I think) has started to fill in.
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Jet Eye Master
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What's all the jetting now? Piston looking way better.
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120/be~5 (bit leaner than)/123 to 125 MJ.
55/100 idle.
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Jet Eye Master
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Try the BE4 again. Might need a real BE5 or main jet still too small. Need to find the splutter point. Until you know that it's all just guess work.
It did a long run, so not a long way out.
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Ok - installed the AFM and ran a quick test.
120/BE~5/125. 55-100

So this set up has felt good to ride.
It does have a small hitch at hand-off - not that easily exposed - but its there.

I ran it at half throttle and let it go all the way to max RPM.
It read in the high 14's and flashed in the 15's (it jumps around a bit) when at high RPM.

Then I ran it at WOT in same manner. Here is showed mid 14's - but flashed higher and lower within 14's.

My takeaway - a slightly less rich atomizer would likely bring the middle down. My understanding is - idle at 14, mid around 13, and WOT at 12.5 - is the target.

Suspect I could also go a point richer on main.

Anyone wanna comment on that?
close look you can see it just behind floor board coming out of top of exhaust pipe.
close look you can see it just behind floor board coming out of top of exhaust pipe.
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charlieman22 wrote:
Ok - installed the AFM and ran a quick test.
120/BE~5/125. 55-100

So this set up has felt good to ride.
It does have a small hitch at hand-off - not that easily exposed - but its there.

I ran it at half throttle and let it go all the way to max RPM.
It read in the high 14's and flashed in the 15's (it jumps around a bit) when at high RPM.

Then I ran it at WOT in same manner. Here is showed mid 14's - but flashed higher and lower within 14's.

My takeaway - a slightly less rich atomizer would likely bring the middle down. My understanding is - idle at 14, mid around 13, and WOT at 12.5 - is the target.

Suspect I could also go a point richer on main.

Anyone wanna comment on that?
I was able to get my best readings going up a small slope, the light load calmed things down on my meter. I would try a richer main also to see what you get. I was never lean enough to get in the 15's mid range. I would richen that area up a bit also. Meter is telling you your lean in both areas. I was always rich working my way to lean, when I started I was in the 9:1 area and wouldn't rev out. I kept moving leaner until I got to about 12 - 13 and stopped. I never used dyno software to measure, so now you have two data points to use. I am interested to see where this guides you along with your other tools, such as dyno numbers and graphing.

Didn't you end up going to a richer modified BE5 atomizer already with some improvement? The meter kept me out of the weeds and from going in the wrong direction with tuning.
⚠️ Last edited by Christopher_55934 on UTC; edited 1 time
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UTC quote
charlieman22 wrote:
I ran it at half throttle and let it go all the way to max RPM.
It read in the high 14's and flashed in the 15's (it jumps around a bit) when at high RPM.

Then I ran it at WOT in same manner. Here is showed mid 14's - but flashed higher and lower within 14's.

My takeaway - a slightly less rich atomizer would likely bring the middle down. My understanding is - idle at 14, mid around 13, and WOT at 12.5 - is the target.
Stochastic ideal is 14.7:1. Max power output is 12.7:1, both assuming you're getting accurate readings. That's the real rub with the AFM: It's hard to know if the numbers you're getting are accurate or not, and also, I suspect, part of Jack's reticence to rely on them too heavily.

I use mine more as a change detector and symptom verification tool--if I have a flat spot, it can not only validate that it exists, but also get an idea of how big & bad that spot is to reduce the number of jetting changes it takes to get to the jumpoff point for finer tuning. I also validate that any change I've made hasn't had unwanted effects elsewhere in my carb setup that might require me to back out the change and re-think it, or catch me off guard somewhere else along the way.

CM Actual out
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Nedminder
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Christopher - thanks. I'll try it going up hill to see if it steadies.
So many gauges and wires on the bike currently - looks like the car from back to the future.

CM(O) - for Original -
Heard the term before but had to look it up.
"Stochastic: randomly determined; having a random probability distribution or pattern that may be analyzed statistically but may not be predicted precisely."
Having a Stochastic Ideal seams an oxymoron. Which ironically, is at least a 50% accurate description of me!

I would think that the higher 14.7 number - which is leaner - would be less powerful than the 12.7 max power number.
I've also read that with 2stroke - you wanna be a bit lower than the 14.7.
Any thoughts on that?

Anyway - I will play with both the atomizer and the main jet and combine with the Dyno to see if I get a bit more optimized power output.
Running a 125 now. I've run 128 before and it felt/measured lower on the dyno.
So I've used my jet reamer to make a 26.5 MJ for todays test.
Have a little incline I can use to see how it does.
Will squeeze every ounce we can outa the SI.

Thanks gents.
-CM(N)
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I thought I'd just throw this in here to add fuel to the fire. Makes a good case for staying a little on the rich side.

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I was about to throw that image in, too, V oodoo .

Sometimes, I think alike with great minds.

And if for a busy headset, this is mine, only missing the handheld GPS unit for properly accurate speed readings, plus the cell phone mount and GoPro that I'll be rocking for Slaughterhouse this weekend. I'll be like a Mod, but with gauges and cameras instead of mirrors and lights.

And I may even get the wires moved inside the frame, too, if my schedule allows.
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Jet Eye Master
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UTC quote
Everything and everyone says, even new AFR meter, says it's too lean. Find the flood point and it will all become obvious.

Jetting until it floods seems like a waste of time but if this had been done months ago we might have found more power. The Malossi will blow easier, so better to practice on the BGM.
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UTC quote
pheasant plucker wrote:
I love how this thread keeps resolving. (Fairly) instant gratification! You move so fast ;P

I feel like I've read mixed things about the use of exhaust meters on Vespas? Guess we'll find out soon enough. Just hope it doesn't send you down another rabbit hole... reckon you should trust the plug, piston crown and dyno over the AF meter until you are sure it is giving legit and useful data.

Eagerly waiting to see how it goes.
I'm enjoying it as well , just staying quiet sitting on my milk crate taking it all in, so much great information is being shared. Keep it up CM.
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a not so normal vbb2 '64, a weirdo vbx '86, a not so normal pts100 '82 and a yellow sunshine '74 sprint
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UTC quote
chandlerman wrote:
I was about to throw that image in, too, V oodoo .

Sometimes, I think alike with great minds.

And if for a busy headset, this is mine, only missing the handheld GPS unit for properly accurate speed readings, plus the cell phone mount and GoPro that I'll be rocking for Slaughterhouse this weekend. I'll be like a Mod, but with gauges and cameras instead of mirrors and lights.

And I may even get the wires moved inside the frame, too, if my schedule allows.
this is high tech 8)
OP
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UTC

Nedminder
62 VBB1T Round Tail W/ leaner sidecar
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Nedminder
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Quote:
Jetting until it floods seems like a waste of time but if this had been done months ago we might have found more power. The Malossi will blow easier, so better to practice on the BGM.
Meh - I've learned how to fly closer to the sun without having my wings melt off. Invaluable!
What doesn't kill you...

Have been walking MJ up - just like they say you should 🙂 - and with each step I learn a little something. Have a 127 in there now. I would have described it as feeling fat before - but perhaps my perception of lean/fat needed recalculating...

However - might have to go back and re-drill the hole in the carb float chamber. Feels to me to be running out of fuel due to higher consumption of the larger jet. Float chamber isn't draining - but jet silo is I think. Now I understand why float chamber lifts are used... Prefer the hole drill method to avoid the potential side effects of float top lift.

Will investigate. Other shenanigans I pulled inside the carb likely responsible (JB welded the hole and re-drilled at ~2 mm down from 2.3 before JB. May need to bring back up to 2.2/2.3.

CM(o) - that picture made me laugh my ass off. You have trained your eye to flash to all the rich spots - on non homogenous gauge faces - placed in disparate positions. No one else could successfully ride that scoot like you can.

Voodoo - Very helpful graph. Appreciate you guys pulling stuff out of the library for me like that.
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Molto Verboso
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Molto Verboso
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I hope this is just a trick of the light and not the bodge poking through...

But WTF is going on here???
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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UTC quote
I do like the way you will try everything you can think of before doing it the way that is known to work. Like only reading the instruction booklet if you absolutely cannot work it out.

With the correctly mounted AFR meter 12.6 is the goal. However, they are +/- 1.0 so you will need that ear at some point.
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Molto Verboso
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Molto Verboso
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Jack221 wrote:
I do like the way you will try everything you can think of before doing it the way that is known to work. Like only reading the instruction booklet if you absolutely cannot work it out.

With the correctly mounted AFR meter 12.6 is the goal. However, they are +/- 1.0 so you will need that ear at some point.
I think Jack is trying to say it's still lean man... Popcorn emoticon

Perhaps CM22 is thinking he has found the flooding point... but what he is finding is something else. Maybe fuel starvation like he mentioned? The walking up the jetting and loosing power feels or comes across as flooding?

Maybe you need a new carb... Clown emoticon
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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UTC quote
charlieman22 wrote:
CM(o) - that picture made me laugh my ass off. You have trained your eye to flash to all the rich spots - on non homogenous gauge faces - placed in disparate positions. No one else could successfully ride that scoot like you can.
Well, the key is that I usually don't need all that information, because I know the motor is setup correctly and the AFM is not normally on there. I just stuck it on (magnets on the mount) for effect.

Basically, I use the CHT either when the motor is warming up so I know it's warm or on longer, speedier runs, as well as an ongoing sanity check that nothing is off and causing a spike.

The tach is, along with a little mental math, my secondary speedo, both because...well, Vespa speedo...and also to know how hard I'm revving it.

The EGT is new and I HATE that housing. It's too big and the stem is way too long, which makes it all even worse. I just keep forgetting to get a new pod ordered. That face is also larger than I was wanting, but I do like the analog gauges. That same site (aircraftspruce.com) has gauges with both CHT & EGT in the same gauge, but they were out of stock and so I went ahead and got just the EGT. It's still rather large for my tastes, but my ultimate design would have the dual gauge tucked in between the speedo and where the CHT is now, and an analog tach matching to the left.

Eventually, I may may fabricate a custom mount for a pair of analog gauges, but that obviously hasn't happened yet.
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Nedminder
62 VBB1T Round Tail W/ leaner sidecar
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Nedminder
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UTC quote
Lemme start here:
The scoot is running better than it ever has on an SI carb.
Responsiveness in first half of the throttle is legit.
Power comes on down low and smoothly.
Great through the middle as well.
From the light - there is no struggle to get out in front of traffic and separate.

The starvation issue is fixed.
We all know the feeling - from the (multiple) times we've set off and forgotten to open the fuel tap... the moment when you open the throttle expecting BaWAAAAAAAA! - and instead you get that hollow BaWOOOOOOO. Damn!

Hole in the bottom of the float bowl was restricting - likely do to a bodge rework I had previously done.
2.3mm now and motor is very happy (2.3 over supplied the Polini making it hard to jet and knife edged which is why I bodged a patch).
Quote:
I think Jack is trying to say it's still lean man...
I heard him twice the first time. 🙂
And following the advice closer than apparent.
The point of going super rich and walking down is safety.
It's good advice - but you still have to do the walking.
I already know I am safe - as I have walked up from 112.
It's at or near full power now - and I will keep walking one increment at a time using hand reamed jets until I see diminishing returns.
Ironically - this should speed not slow jetting in from this point - rather than finding super rich and having to re-find this range.

AFR is in the 13's with the 127MJ.
Looking at Voodoo's graph - it suggests I have a few more steps to go - though at the cost of fuel economy.
12.6 per his graph will likely occur around 130ish.
Perhaps I will end there.
Will be interesting to see Dyno vs AFR.
Speed run with 2.3mm hole.  Second time I have seen 18+.  Very smooth.  It's close.
Speed run with 2.3mm hole. Second time I have seen 18+. Very smooth. It's close.
This suggests as I go richer - it will gain power over optimized leaner setting.
This suggests as I go richer - it will gain power over optimized leaner setting.
@ginch avatar
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Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
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@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
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UTC quote
Watching this epic race between teacher and student. Popcorn emoticon
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Ossessionato
1963 VBB2T
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Ossessionato
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1963 VBB2T
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UTC quote
Geez CM be careful you don't go down the rabbit hole too deep, try to get a safe medium, you got a nice ride going on there side car and all, just be careful. 12.6 is a pretty respectable number .
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Molto Verboso
bare metal cafe racer
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Location: Aotearoa (New Zealand)
 
Molto Verboso
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bare metal cafe racer
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UTC quote
Still haven't answered me and allayed my concerns... what is going on near the engine mount point on the frame?
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