Who is Bald John and what is his magic sauce jetting?
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Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1531
Location: UK (South East)
Mon Jun 01, 2020 8:47 am quote
I keep hearing references to the 'Bald John' stack, which, as far as I can tell is a fairly typical 160/BE3/xxx and 55/160. This is standard fare for a UK PX200 with a 24/24E carb. Now that I'm experimenting with a 140AC in conjunction with the BE3 and smaller main jets than I've grown accustomed to, I'm starting to see good results (this on a 200+cc engine). Is the Bald John stack essentially a thing of the past, or does it still apply to certain setups? It seems that the key here is the modifications made to the carb, notably the drilling of the passage between float bowl and main stack channel. Was this not done by many people until fairly recently?

As usual, I may be missing something.
Hooked
Stella 2T 150, Honda C70
Joined: 25 Sep 2019
Posts: 136
Location: Seattle
Mon Jun 01, 2020 9:53 am quote
See the attached article. Its basically de-restricting a Stella to make the engine breath a little better and as such go faster. The stock Stella air cleaner is pretty restrictive and it also has a secondary air filter up under the seat. Ditch the one under the seat. For the air cleaner, you can either just de-blue it or simpler, just put on a stock P200 air cleaner.

I also put on an SR Race exhaust (Sip Road 2 clone) as the Stella catalytic exhaust is pretty restrictive.

For jetting I'm running a 55/160 idle jet and for the main stack a 160 air corrector, BE3 mixer and 100 main. Its worth checking what you already have but the Stella came stock with an E3 mixer which is not the same as the BE3.

Hal

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Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1531
Location: UK (South East)
Mon Jun 01, 2020 11:56 am quote
Thanks Hal. I wasn't aware that this 'Bald John' jetting thing started with an LML project. Anyways, seems like SI carb tweaks and jetting ideas have evolved since then, probably in line with kit developments.
Hooked
Stella 2T 150, Honda C70
Joined: 25 Sep 2019
Posts: 136
Location: Seattle
Mon Jun 01, 2020 4:50 pm quote
I don't mean this any other way than out of just basic curiosity, but how have things evolved? I'm currently running this setup and I like it -- it is a VAST improvement over the stock Stella configuration. If that is your setup, with the 20/20 carb and a freer flowing exhaust, the jetting is either optimized or it isn't. That was my basic takeaway from the article -- make it breathe easier, adjust the jetting to match and you have a much more tractable scoot for less than $200 in spend. There are always other mods like changing stroke or displacement, but I'm really interested in how far I can push 150cc and still be as reliable as with my 3mm+ of squish.

That said I did order Boyesen reeds today, and may end up going down the route of opening up the exhaust port and shaving the head.

Hal
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1778
Location: california
Mon Jun 01, 2020 8:33 pm quote
SWA - good question.
I've used the "Bald John" jetting - and the terminology - but frankly not sure where I heard it.
Maybe Hal's article!

Was tough to leave it behind based on Jack's suggestions.
But the outcome of going to the larger float chamber hole/smaller main/ AC 120 was pretty damn positive.

Not sure I could have run as hard WOT for as long with the 160.
Could just be my perception - but liked the smaller AC enough to brand it JackStack after getting such good results.

Hey - if Bald John can have a stack - why not Jack.
Also - it rhymes - which must make it better.

Kidding asside - would like to hear other's perspective on your orig. question.
Can the 160 do the same job in an un drilled carb?

-CM
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1531
Location: UK (South East)
Mon Jun 01, 2020 9:42 pm quote
whereshaldo wrote:
I don't mean this any other way than out of just basic curiosity, but how have things evolved? I'm currently running this setup and I like it -- it is a VAST improvement over the stock Stella configuration. If that is your setup, with the 20/20 carb and a freer flowing exhaust, the jetting is either optimized or it isn't. That was my basic takeaway from the article -- make it breathe easier, adjust the jetting to match and you have a much more tractable scoot for less than $200 in spend. There are always other mods like changing stroke or displacement, but I'm really interested in how far I can push 150cc and still be as reliable as with my 3mm+ of squish.

That said I did order Boyesen reeds today, and may end up going down the route of opening up the exhaust port and shaving the head.

Hal
Hello Hal, your response answered this perfectly. Sounds like the Bald John setup was extremely well researched and tested on the Stella in that article. I'm not surprised it works so well for you. My own setup is a kitted 225 tourer, so when I kept hearing references to this magic 160/BE3/xxx and 55/160 setup, to me it was the quite ordinary, tried and tested P200 24/24E setup from long ago. Only the size of the main jet is different.

I'm beginning to realise that 160 and BE3 don't need to be paired and are not the only/best combo for my type of need. As I have been taking advise from Jack and others on here and understanding more (for example) about how the fabled T5 works with it's mystical 24/24G setup, I'm seeing other possibilities with the venerable SI carb. Also, in experimenting with the BE2 atomiser, I've realised something that feels good may not be so good for the health of my Vespa.

These 'new' ideas may not be new after all, but I've read some really cool stuff on here lately about SI carbs. I guess that's the difference between those of us that can get our carbs in the ball park, and those that understand the science. Take the recent threads about float top spacers for example. That's what I mean by evolving. Old hat for seasoned tuners maybe, but gold dust for the likes of me on this forum.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1531
Location: UK (South East)
Mon Jun 01, 2020 9:50 pm quote
charlieman22 wrote:
SWA - good question.
I've used the "Bald John" jetting - and the terminology - but frankly not sure where I heard it.
Maybe Hal's article!

Was tough to leave it behind based on Jack's suggestions.
But the outcome of going to the larger float chamber hole/smaller main/ AC 120 was pretty damn positive.

Not sure I could have run as hard WOT for as long with the 160.
Could just be my perception - but liked the smaller AC enough to brand it JackStack after getting such good results.

Hey - if Bald John can have a stack - why not Jack.
Also - it rhymes - which must make it better.

Kidding asside - would like to hear other's perspective on your orig. question.
Can the 160 do the same job in an un drilled carb?

-CM
CM, soon there won't be anyone left with an undrilled carb, and all the 160 air correctors will end up in retirement homes.
Molto Verboso
08 GTS 250, 79 P200E, 62 Allstate
Joined: 11 Jan 2006
Posts: 1754
Location: Florence, OR
Tue Jun 02, 2020 8:50 am quote
swa45 wrote:
These 'new' ideas may not be new after all, but I've read some really cool stuff on here lately about SI carbs. I guess that's the difference between those of us that can get our carbs in the ball park, and those that understand the science. Take the recent threads about float top spacers for example. That's what I mean by evolving. Old hat for seasoned tuners maybe, but gold dust for the likes of me on this forum.
Gold Dust big time. For me as well swa...

And I'm diggin the JackStack! Perfect way to coin this CM - Jack is THE MAN!
Ossessionato
1980 P200E , 2005 Stella 177
Joined: 20 Jul 2018
Posts: 2189
Location: Staten Island, NY
Tue Jun 02, 2020 8:52 am quote
qascooter wrote:
And I'm diggin the JackStack! Perfect way to coin this CM - Jack is THE MAN!
Jack is owed some serious drinks.
Hooked
Stella 2T 150, Honda C70
Joined: 25 Sep 2019
Posts: 136
Location: Seattle
Tue Jun 02, 2020 3:58 pm quote
Ok now I'm back with different questions. There are a lot of posts here and my work life is a little nutso right now so I don't have a ton of time to dive in as deep as I may want to.

Drilling the carb -- why? what posts should I read?

Jack Stack -- I like a good rhyme but sounds more like a late night drunken burger choice. whats up here?

I've also seen some things about raising float height.


Also if someone can correct me if my assumptions are wrong:

Goal is to push 150cc as far as possible. Porting, boyesen reeds, general air flow. All of this should still be doable with the 20/20 unless I'm really missing something. I'd like to say I'm getting to ride for hours at WOT from here to Bend OR or something but I'm not, its mainly just 3-5 mile back and forth to work jaunts, and some sightly longer weekend rides. My primary curiosity is to get the stock 20/20 and stock 150 jug as optimized as possible and get every possible newton (?) out of the scoot without having too much downtime.

Hal
Hooked
PX125E
Joined: 06 Oct 2018
Posts: 175
Location: Gravesend, Kent, UK
Tue Jun 02, 2020 4:18 pm quote
Hello SWA and Friends.
Iím asking here about an idea. I donít want to waste time if Iím talking out my arse here.

I have a standard air filter which I dismantled. I dremeled the webs inside the casting and am going to replace the filter gauze with a strip of aluminum mesh.
Itís untested and based on this Forum and Mr Freak mopeds videos.
Do you think itís worth an explanation please?
Hooked
P Series / Li / LML / Motobi
Joined: 24 Jun 2019
Posts: 409
Location: UK - 3rd Rock From the Sun
Wed Jun 03, 2020 2:26 am quote
what type as in size hole mesh will you be using? I have been considering a similar approach to this for making a filter for my PHBH and was unsure what diameter hole mesh to get
worrywort wrote:
Hello SWA and Friends.
Iím asking here about an idea. I donít want to waste time if Iím talking out my arse here.

I have a standard air filter which I dismantled. I dremeled the webs inside the casting and am going to replace the filter gauze with a strip of aluminum mesh.
Itís untested and based on this Forum and Mr Freak mopeds videos.
Do you think itís worth an explanation please?
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1531
Location: UK (South East)
Wed Jun 03, 2020 3:57 am quote
Hello Del, what is your objective? I've always used standard PX200 filters with one or two holes in the heart. I've never attempted to 'enhance' one further than that. On the occasions that I've wanted to experiment with greater air flow, I've used a venturi/bellmouth or a downdraught carb with no filter, just the rubber bellows into the frame.
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1778
Location: california
Wed Jun 03, 2020 7:52 am quote
Quote:
soon there won't be anyone left with an undrilled carb, and all the 160 air correctors will end up in retirement homes.
Agreed - seems like "our generation" is evolving the stack to smaller AC, smaller main. For what it's worth - the Bald John was being applied to a tuning that was producing a 62MPH max speed. Many of us are now tuning to cruz at that and above with a max that would be significantly higher.
Quote:
Drilling the carb -- why? what posts should I read?

Jack Stack -- I like a good rhyme but sounds more like a late night drunken burger choice. whats up here?

I've also seen some things about raising float height.
Drilling:
Because the carb has reached a limit and can't feed the main jet. Reason - the hole in the bottom of the float chamber has become the limiting passage rather than the hole in the main jet. Meaning - up-jetting is not having its intended effect because the carb cant feed the larger jet. Result - you think you have a larger jet in - but jet is not being fed, is acting like a smaller jet, and motor is being starved.

JackStack - because:
A. Jack has been advising and helping us all jet our carbs - to nice success - and has advised smaller AC than the old favored AC160 that most of us had a comfort level with.
B. If Bald John can have a stack - why not Jack?!

Float height. This is a bit more hit and miss in my view. It's done to:
A. Ensure you don't run the float reservoir dry.
B. Keep the level higher in the jet stack (not JackStack) tube - requiring less pull to feed the jetting.
Lifting this level has been a mixed bag for some of us - personally, I see it as a fix if you have a specific issue - but not a tuning step that needs taking if not.
Quote:
My primary curiosity is to get the stock 20/20 and stock 150 jug as optimized as possible and get every possible newton (?) out of the scoot without having too much downtime.
The 20/20 can certainly still be used. A larger carb will have more effect on the top end than putting around town. The article you posted still has merit in my view. For simple plug and play, a performance exhaust and better reeds are probably the quickest and cheapest. This would be accompanied by an up-jetting of your 20/20. If your current jet is around 100? going to a 110 may not require any drilling or modifications. In my view, the tipping point likely gets close when you put a new jug of larger CC on it. Other's can give their opinion.
Hooked
Stella 2T 150, Honda C70
Joined: 25 Sep 2019
Posts: 136
Location: Seattle
Wed Jun 03, 2020 12:52 pm quote
Ok this all makes a lot more sense now. From my end, I am not interested in changing the displacement at all. I want to get the 150 blueprinted so that it is running optimally by working on the ports and tuning the squish. But having done all that I'm probably looking at a top speed of 60 flat out with a tailwind and at best I'll be holding that for 5 or 10 minutes. Its just not how I'm riding it.

My interest is in making the platonic ideal of the Stella 150cc 2T engine just because that's what floats my boat. I know there are a lot of ways to go faster, and maybe I'll get there but I like just trying to squeeze out every bit of power from a relatively stock setup.

H
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7958
Location: Victoria, Australia
Wed Jun 03, 2020 3:04 pm quote
Bald John was part of the StellaSpeed forum. Was a good forum but wound down maybe 7 years ago?

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2856
Location: Nashville
Wed Jun 03, 2020 6:34 pm quote
Yeah, StellaSpeed died off after an attempt at re-branding some time ago. I was active on there prior to coming over here with its demise. Most of the posts can still be found in the Internet Archive, albeit without any posted images.

I kind've wish it was still around just so I could go read my early, flailing ignorance. Plus, there were some really solid tuning threads on there, which I would now appreciate.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7958
Location: Victoria, Australia
Wed Jun 03, 2020 7:22 pm quote
chandlerman wrote:
Yeah, StellaSpeed died off after an attempt at re-branding some time ago. I was active on there prior to coming over here with its demise. Most of the posts can still be found in the Internet Archive, albeit without any posted images.

I kind've wish it was still around just so I could go read my early, flailing ignorance. Plus, there were some really solid tuning threads on there, which I would now appreciate.
It was ok after the name change, just for a while it was un-moderated and filled with spam. That's when I stopped going there.

This one I re-found a while ago - https://web.archive.org/web/20160310065830/http://www.scootercentral.net/forums/viewtopic.php?t=16229

And this attached was my favourite inspirational thread on the forum. For some reason I had the foresight to save the web pages!

Need some guidance please! 'Japanizing' the engine -Performance Scooter Tuning, Maintenance & Repair_files.zip
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 Filename:  Need some guidance please! 'Japanizing' the engine -Performance Scooter Tuning, Maintenance & Repair_files.zip
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Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2856
Location: Nashville
Thu Jun 04, 2020 3:52 am quote
If I ever can get back to it, I'm going to put a 60mm Sprint crank into my VBB, so I'll be doing that exact same swap, as described in the article. I've spent a fair amount of time contemplating it, and I think it'll work just fine, especially given that this will be a mild tune (it's a two-port motor, so it has to be ).

I remember the Japan-izing thread, mostly because when I read it, it mostly taught me how little I knew about what I was doing, as if the volume of blown up parts wasn't indicator enough.

OK...back to Air Correctors

Now that I have the PM Tuning pipe on my Sprint, I can swap my Big Box with the Air:Fuel Meter bung on it over to my Stella and test out the air corrector theories from this thread. That may not be until first part of July, when I'll be left without adult supervision for a couple weeks.
Member
GT 125 (03), PX 166 (99) S3 (66) Imola 186
Joined: 19 Nov 2017
Posts: 45
Location: Nr Exeter Devon UK
Thu Jun 04, 2020 5:24 am quote
Hello Lads
i,m also on the lower AC'S now,.....140 for me currently ( 166/venturi/pm pipe),
A lot more confidence rather than the 160,.....
Everything under control nicely below the mythical 300F
Much Happier kaining it !!!!!and riding it like you stole it !!!! lol,...
Keep up all the good work everyone,.....
All the best
pek,...
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1778
Location: california
Thu Jun 04, 2020 8:07 am quote
Quote:
Now that I have the PM Tuning pipe on my Sprint, I can swap my Big Box with the Air:Fuel Meter bung on it over to my Stella and test out the air corrector theories from this thread. That may not be until first part of July, when I'll be left without adult supervision for a couple weeks.
So much good stuff packed in that one passage I just had to repost.
1. Love the idea of measuring some comparisons if it can be done.
2. Best time of year! Work in the garage when its nice and cool out, music on, from 10:00pm until midnight - guilt free!

🙂
Ossessionato
1980 P200E , 2005 Stella 177
Joined: 20 Jul 2018
Posts: 2189
Location: Staten Island, NY
Thu Jun 04, 2020 10:21 am quote
All this pm tuning talk got me looking at mine sitting in the corner. I just ordered the missing parts to dust that off and test it out on my Stella soon. Interesting to see how it compares to road xl
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2856
Location: Nashville
Thu Jun 04, 2020 10:22 am quote
swiss1939 wrote:
All this pm tuning talk got me looking at mine sitting in the corner. I just ordered the missing parts to dust that off and test it out on my Stella soon. Interesting to see how it compares to road xl
The power band is a little bit narrower, with the loss on the bottom end, but when it gets on the pipe, it's a screamer.
Hooked
PX125E
Joined: 06 Oct 2018
Posts: 175
Location: Gravesend, Kent, UK
Thu Jun 04, 2020 3:39 pm quote
Gravelrash2004 wrote:
what type as in size hole mesh will you be using? I have been considering a similar approach to this for making a filter for my PHBH and was unsure what diameter hole mesh to get
worrywort wrote:
Hello SWA and Friends.
Iím asking here about an idea. I donít want to waste time if Iím talking out my arse here.

I have a standard air filter which I dismantled. I dremeled the webs inside the casting and am going to replace the filter gauze with a strip of aluminum mesh.
Itís untested and based on this Forum and Mr Freak mopeds videos.
Do you think itís worth an explanation please?
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7958
Location: Victoria, Australia
Thu Jun 04, 2020 10:22 pm quote
chandlerman wrote:
If I ever can get back to it, I'm going to put a 60mm Sprint crank into my VBB, so I'll be doing that exact same swap, as described in the article. I've spent a fair amount of time contemplating it, and I think it'll work just fine, especially given that this will be a mild tune (it's a two-port motor, so it has to be ).
Will you be machining a new circlip groove in the clutch side bearing housing for this?
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2856
Location: Nashville
Fri Jun 05, 2020 4:20 am quote
Ginch wrote:
chandlerman wrote:
If I ever can get back to it, I'm going to put a 60mm Sprint crank into my VBB, so I'll be doing that exact same swap, as described in the article. I've spent a fair amount of time contemplating it, and I think it'll work just fine, especially given that this will be a mild tune (it's a two-port motor, so it has to be ).
Will you be machining a new circlip groove in the clutch side bearing housing for this?
Nope. Last night, after going back and forth about twenty times, I ultimately decided to just kamikaze it and installed the bearing and seal with retaining compound. With the way that the P crank sits in the bearing, it's trapped between the lip of the crank and the outside circlip. I don't anticipate this motor putting out enough power to twist a Mazzi race crank, although I've been known to surprise myself on stuff like that some days.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7958
Location: Victoria, Australia
Fri Jun 05, 2020 4:51 am quote
Livin' on the edge!
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2856
Location: Nashville
Fri Jun 05, 2020 4:57 am quote
Ginch wrote:
Livin' on the edge!
LOL! Yep! I have an LML motor with a Malossi 166 on it right now that I converted to 8" for it, but it needs some teardown love, so I'll probably get that sorted next.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2284

Sun Sep 13, 2020 10:24 am quote
charlieman22 wrote:
Quote:
soon there won't be anyone left with an undrilled carb, and all the 160 air correctors will end up in retirement homes.
Agreed - seems like "our generation" is evolving the stack to smaller AC, smaller main. For what it's worth - the Bald John was being applied to a tuning that was producing a 62MPH max speed. Many of us are now tuning to cruz at that and above with a max that would be significantly higher.
Quote:
Drilling the carb -- why? what posts should I read?

Jack Stack -- I like a good rhyme but sounds more like a late night drunken burger choice. whats up here?

I've also seen some things about raising float height.
Drilling:
Because the carb has reached a limit and can't feed the main jet. Reason - the hole in the bottom of the float chamber has become the limiting passage rather than the hole in the main jet. Meaning - up-jetting is not having its intended effect because the carb cant feed the larger jet. Result - you think you have a larger jet in - but jet is not being fed, is acting like a smaller jet, and motor is being starved.

JackStack - because:
A. Jack has been advising and helping us all jet our carbs - to nice success - and has advised smaller AC than the old favored AC160 that most of us had a comfort level with.
B. If Bald John can have a stack - why not Jack?!

Float height. This is a bit more hit and miss in my view. It's done to:
A. Ensure you don't run the float reservoir dry.
B. Keep the level higher in the jet stack (not JackStack) tube - requiring less pull to feed the jetting.
Lifting this level has been a mixed bag for some of us - personally, I see it as a fix if you have a specific issue - but not a tuning step that needs taking if not.
Quote:
My primary curiosity is to get the stock 20/20 and stock 150 jug as optimized as possible and get every possible newton (?) out of the scoot without having too much downtime.
The 20/20 can certainly still be used. A larger carb will have more effect on the top end than putting around town. The article you posted still has merit in my view. For simple plug and play, a performance exhaust and better reeds are probably the quickest and cheapest. This would be accompanied by an up-jetting of your 20/20. If your current jet is around 100? going to a 110 may not require any drilling or modifications. In my view, the tipping point likely gets close when you put a new jug of larger CC on it. Other's can give their opinion.
That there is some excellent information.
Enthusiast
2005 Stella 2T
Joined: 14 Jun 2020
Posts: 61
Location: MA
Sun Sep 13, 2020 1:12 pm quote
I recently went through this after putting a Polini box and a predrilled air filter on my otherwise stock Stella. For me, the biggest problem with the Bald John jetting was the 55/160 idle jet. It made my scooter way too rich at partial throttle, causing a nasty pop, pop, pop, pop from the exhaust during deceleration. Going back to the stock 40/130 idle jet cured that. Since then, I have gone to a 42/140 idle jet; no pop, pop, pop, pop and seems to run a little smoother at partial throttle than the 40/130.

The other problem was that the 160 air tube/BE3 mixing tube combo probably was too lean at WOT. I say ďprobablyĒ because, after receiving dire warnings my motor would blow up, I went to a stock 140 air tube and a nonstock BE5 mixing tube without really testing the theory. My own theory is that it is the mixing tube that really matters and the air tube is not critical. I may pick up a 120 air tube and a BE1 mixing tube to round out my set and then start mixing and matching to see what I get.
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