Modern Vespa

hey folks.....

anyone got any experience of PHBL carbs on GS150 engines? i just picked a gs150 up with a PHBL 20 on it. ive only ever been familiar with flat side vespa carbs so am a bit stumped on these. engine starts on choke, then overrrevs like crazy, then dies. wont start at all without choke. spark looks ok, fuel is getting in ok...im using 1 and 1/2 turns on airscrew (like a flatside) is that right?

pic1

carb shot

was an air issue........check out the split carb rubber........hopefully a new one will fix it!

Nice find on the crack keep an extra boot on hand your GS looks great did you do the carburetor modification yourself? Any other mods?

Would not be hard to fit an si carb

If it was mine I'd fit an SSI25 as a vintage race mod

hibbert - nah it was already on it. good call to have a spare rubber mount tho....that's a damn fine idea! cheers!

its got an odd choke setup too ... see piccy

im more familiar with P Series / large frame in general so taking some time to find my way around these wide frames.

got a link ? might well be the call.....

Wow that is clean. I'm using a similar rubber on my P200 seems like I replace it as often as the kick stand feet.

Get a Kevlar reinforced connecting rubber and you're done. Even a car radiator hose will do. Polini or Malossi rubbers split all the time...

https://www.ebay.com/itm/DELL-ORTO-CARBURETOR-SSI-25-DELLORTO-SS1-VINTAGE-DUCATI-PARILLA-MV-GUZZI/362710883867?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Da802206a225c4122a5c06d9f853e1801%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D362710883867%26itm%3D362710883867%26pg%3D2481888&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A142f3f74-b581-11e9-8f19-74dbd18075c5%7Cparentrq%3A54c2fc7116c0a4e88437f5a3ffe287a4%7Ciid%3A1

they can be setup for downdraft and were used on all the Piaggio factory race bikes. this listing is over priced but they can be found for ~250. but then you have to add the float that allows it to be used in down draft mode or a remote float, that will add another 150-250. look would be spot on, but performance would same as fitting an SI24 from a p200. Seem to recall that someone made an airbox to fit on the SI24 that had the look of the 150 GS.

I'm sure these will last longer, but I wondered whether these would transmit more vibration to the carb than the softer ones? I haven't split one yet but carry a spare.

Makes perfect sense ! Thanks !

Thanks mate - will dig into it.

we are now up and running, and im buzzing round town. and i can get tick over/idle. but.....runs like dogshit at half+ throttle.....can barely get over 40 mph. new carb is on the horizon, but.....in a lasy chance to save me a few quid, anyone know a good jetting setup for a phbl 20 on a 150 engine? if that fails....then its new carb time

That would be a stand out solution.
Fan of the GS airbox design.

Any idea where you saw this?

Can't find it, don't think it would be that hard to fabricate here's some pictures to help with motivation:

here's a GS150 with SSI27 carb on it (easier to find than the 25mm but then you have to tune it...)


and more on that engine:
https://www.germanscooterforum.de/topic/177570-vespa-150-gs-mit-150gs-motor/

sources for repop air boxes, so you don't have to feel bad modifying one.
https://www.motoricambisoviero.it/catalogo/-Scatola-Filtro-Aria-Carburatore-Vespa-150-GS-VS2-VS3-VS4-VS5--3663

http://www.vespashop-bestmotor.com/it/carburatori/2020-cassa-filtro-aria-completa-vespa-150-gs.html

Those carbs are gorgeous. Were they also used on Ducatis and Guzzis of that era?

[quote]we are now up and running, and im buzzing round town. and i can get tick over/idle. but.....runs like dogshit at half+ throttle.....can barely get over 40 mph. new carb is on the horizon, but.....in a lasy chance to save me a few quid, anyone know a good jetting setup for a phbl 20 on a 150 engine? if that fails....then its new carb time

Anything else done to the engine besides the carburetor modification? What is the ignition system looks like it may have a vespatronic?

[quote="charlieman22"] i've got on order a phbl 24 - the current one is a 20 - i'll list the jetting if it sorts it out. keep you posted

yeah - dunno, i haven't gotten into the engine yet, it does also has a battery in the tool box....no idea what this for tho......on the large frames i always remove the battery and electric start motor anyways, they usually break after a year or so.

i'm most definitely on a new journey with these wideframes......

the saga continues.....

turns out that the PHBL BD20 is a 'right hand' carb. ie the cylinder side is on the right looking at at it from the adjuster screw side......air side to the left.

so my brand new shiny PHBL 25 is about a much use as a chocolate tpot...grrrrrrrrr

https://beedspeed.com/products/carburettor-dellorto-25mm-phbl?variant=10570066100267

looks like i gotta battle away with the BD20 - i need a manual badly, all the material i can find on PHBL is telling me that the non spring screw is a fuel screw - and must be 2 to 3 turns out - yet when i adjust it, the engine behavior its much more like an air screw? like a normal vespa PX carb....

very confusing........anyone got any ideas?

the carb i got is here....

https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/complete-carburettors-dellorto-motorcycle-carburettors-parts/phbl-20-to-26mm/r2782-phbl-20bd/

Maybe to identify the fuel screw, take the carb off and turn the screw and see if the valves moves.

Different carb but with similar screw check. https://www.youtube.com/watch?v=A1vRMERs4RQ

good shout bro - ill take a look.....

iggy - can I back us up a few steps?
This bike is gorgeous.
Looks like it lived in a garage - was well kept.
Upgrades look more curated than haphazard.

Made me wonder - maybe it is a well matched system - but you have another issue.

e.g. bad electronic ignition box (assuming ignition is even electronic).

Curious about back story - can you fill us in a little?
Also: can you post up a set of specs that includes ignition/exhaust/ etc.
Would be interesting.

- CM

+1, such a clean bike! What's the story?

While we're at it what's up w/ the T5200, is it a Spanish TX200? Reference: Vespa tx rear shock query

And PX125 cutdown, what? Let's see some pics?

see below!

yeah mate - a scooter mate of mine started on the resto - then got MS, he's currently in hospital - i bought it off his missus...so am picking it up trying to get up to speed quickly and get it running. then i'll go see him in hospital, if its not too late......so i apologies to all if i seem abit desperate.......

cutdown can be seen and heard here mate.

"https://www.youtube.com/watch?v=n19gfrdPJlQ"

Success!!!!!Got her running just great on idle and main jets.

Spec: Vespa GS 1959, 150cc, PHBL 20 DB Carb, B7ES plug.

1) set carb fuel/air screw (or whatever it is) to 2 turns, throttle pics up nice and comes down nice now
2) set idling screw to a decent pace idle tick over
3) moved to a hotter plug : B7ES
4) cleaned jets, fitted kevlar tube connection to PHBL 20BD
5) tweaked up cylinder head bolts
6) noticed oil/fuel leaking from exhaust port, tweaked up exhaust nut (will probably upgrade the pipe soon anyways.....

carb and jet pics attached - big thanks to all ! kudos.....

will take her for a 10 mile run tonight - i will report back.

Cheers!

Good deal, I like those PHBL carbies. Let's see how it does on your 10 mile run.

Meanwhile, you have too many T5's and I have none. But I have many smallframes while you have none. I think we need to arrange a swap here somehow.

you are most correct....i love a T5.....and a gl.....
that vespa square headlight floats my boat........

way better than a GP.....

oohh......now that is tempting.........i love a smally.......oooher missus!

spin out went well......pinging away....think the fork is a bit loose....ill tweak that up tomorrow too.....