PX Keihin carb needs
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Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Sun May 28, 2017 11:39 pm quote
Hello all,

Decided to go from the si carb to the Keihin 28mm.

I'm going to try this setup that Vader suggested in this thread.

Time to graduate from stock/SI carbs?

You can get the intake from scooter centre.

I realise I'm going to need:

Longer throttle cable

Longer airbox hose to the frame

Rubber connector hose

Choke cable kit. Will this work for the Keihin?
(http://www.sip-scootershop.com/en/products/conversion+kit+cablechoke+_40331200)

Starting point for jetting/ Jet kit.

PX Malossi sport, pinasco lightened flywheel, Sip Jl evo pipe, cut crank.

Anybody got any tips or links to the above parts or anything else I need.
Member
Vespa px210
Joined: 16 Feb 2014
Posts: 19
Location: Wales, UK
Mon May 29, 2017 1:15 am quote
Great choice of carb, used Keihin for a few yews now, easy to set up and great performance. you will find a good list of what jets people are running in the Keihin carbs on the Scoots rs website. For some reason the links doesn't seem to work on here.
http://[redacted].com/tech.cfm?tip=jetpwk

Last edited by ukpeckerwood on Mon May 29, 2017 2:52 pm; edited 3 times in total
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: 8055
Location: Victoria, Australia
Mon May 29, 2017 2:23 am quote
You have to replace [redacted] with s c o o t r s (no gaps), and yes, that's a very useful resource.

Here's the cheapest place to buy a genuine PWK that I've found, although I don't think they ship to Aus. Some kind folks here might be able to forward it on for you.
http://www.jetsrus.com/individual_parts/016_144_su.html

Yes the choke conversion will work... that's the very same kit that Scoot RS used to sell for about $4.

I have a Malossi bellows made for this sort of thing and it's hard and too small for the purpose. Pretty sure it hasn't shrunk as it was wrapped on a card and shrink-wrapped, and it wasn't loose inside the packet. Anyone who owns a 3/4 scale Vespa is welcome to it!

Not sure with that intake where the carb will end up in relation to the cylinder cowl, but it tends to make getting to the mixture screw very tricky. You can buy a knurled mixture screw that you can adjust by hand rather than a small screwdriver for this.

The snakehead is a pretty awesome thing that makes it a bit easier running the cable instead of using a bend.

You may need a quicker action throttle pulley so you don't need to turn the throttle as far (which is a bit further than an SI). There are all sorts of solutions but I like the in-line type for ease of fitting (re-use your existing cable). Haven't used one personally but a good friend uses one on his SS180. Can't find it now for some reason frustratingly, it's a little bit like this but smaller -https://www.lambretta-teile.de/Easy-clutch
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Mon May 29, 2017 9:30 pm quote
Ginch wrote:
You have to replace [redacted] with s c o o t r s (no gaps), and yes, that's a very useful resource.



Here's the cheapest place to buy a genuine PWK that I've found, although I don't think they ship to Aus. Some kind folks here might be able to forward it on for you.
http://www.jetsrus.com/individual_parts/016_144_su.html

Yes the choke conversion will work... that's the very same kit that Scoot RS used to sell for about $4.

I have a Malossi bellows made for this sort of thing and it's hard and too small for the purpose. Pretty sure it hasn't shrunk as it was wrapped on a card and shrink-wrapped, and it wasn't loose inside the packet. Anyone who owns a 3/4 scale Vespa is welcome to it!

Not sure with that intake where the carb will end up in relation to the cylinder cowl, but it tends to make getting to the mixture screw very tricky. You can buy a knurled mixture screw that you can adjust by hand rather than a small screwdriver for this.

The snakehead is a pretty awesome thing that makes it a bit easier running the cable instead of using a bend.

You may need a quicker action throttle pulley so you don't need to turn the throttle as far (which is a bit further than an SI). There are all sorts of solutions but I like the in-line type for ease of fitting (re-use your existing cable). Haven't used one personally but a good friend uses one on his SS180. Can't find it now for some reason frustratingly, it's a little bit like this but smaller -https://www.lambretta-teile.de/Easy-clutch


Alright thanks for the tips.

Are you just running a pod filter then? Instead of the bellows.

I have a credit with SIP to use so that's what's getting the pwk.

Can you run a standard length throttle cable then with the snake head?

Also regarding the air screw/mix screw.
I got this off the sip pwk site:

"Explanation of the carburettor markings:
BD carb.= Adjustment screw to the right of the airflow direction
BS carb.= Adjustment screw to the left of the airflow direction"

So would I need the bs? I'm not sure where the mixture screw is on the pwk.

I guess I can run the inline quick action throttle after. If needed.

Cheers
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: 8055
Location: Victoria, Australia
Tue May 30, 2017 12:44 am quote
I just had a pod filter... would like to run bellows but not sure about a filter then.

You'll have to ask Crazy Monkey about the cable. Callum has one on his and I'm not sure if he needed to swap cables.
https://www.facebook.com/crazymonkeydevelopment/

Sorry gave you a bum steer on the mixture screw... mine is a PE and has it on the wrong side. You want the one with the mix & idle speed screws facing away from the frame. I think that makes it a BS, but not sure what "to the right of the airflow direction" actually means. Anyway that would put the mixture screw furthest away from the manifold. Or is that singlefold?
Member
Vespa px210
Joined: 16 Feb 2014
Posts: 19
Location: Wales, UK
Tue May 30, 2017 3:04 am quote
Would recommend getting one off these, quick action throttle wheel and no nipple required as it has a built in clamp. They make them for all types of vespas.
https://www.facebook.com/crazymonkeydevelopment/photos/a.1656273581266890.1073741830.1621051684789080/1838178173076429/?type=3&theater
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Tue May 30, 2017 3:32 am quote
ukpeckerwood wrote:
Would recommend getting one off these, quick action throttle wheel and no nipple required as it has a built in clamp. They make them for all types of vespas.
https://www.facebook.com/crazymonkeydevelopment/photos/a.1656273581266890.1073741830.1621051684789080/1838178173076429/?type=3&theater
Oh easy. I'll add that to the order.

Anyone confirm whether it's the 28bd or 28bs?

Weird because the standard jets in the carb in each model are different and the bd sounds closer to what's needed.
Member
Vespa px210
Joined: 16 Feb 2014
Posts: 19
Location: Wales, UK
Tue May 30, 2017 3:53 am quote
The air mixture screw is in the front and looking from above its to the right of the air flow going into the carb, so i would say you need a BD.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2974
Location: Nashville
Tue May 30, 2017 4:21 am quote
I've run a PWK 28 for a few years now on my Stella and once you get your head around it (and buy a set of needles and jets, plus a bunch of individual needles...), it's great. I ordered the BGM needle & jet sets and they've worked well for me.

With RD-350 reeds, I got almost 17hp from a heavily ported DR 177 on it.

You'll also find that http://kyajet.de/?lang=en is an amazingly helpful tool for getting it dialed in just right.

I didn't do anything with the throttle except swap to a longer cable.

I also have the extended mixture screw. It's a little tight with the cylinder shroud, but still fits. Makes a huge difference with dialing in the mixture.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Wed May 31, 2017 12:59 am quote
Thanks for all the tips so far.

Modern vespa is such a good resource.

Ok so I'll get:

Keihin pwk 28bd

MRP intake

Snakehead (carb top)

Sloth (quick action throttle)

30mm pod style filter

Choke cable kit

Rubber connector

Long throttle cable

Jet kit.

Just gotta source the long cable and the jet kit.

Cheees
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 01, 2017 9:58 pm quote
Ok

All ordered, besides the snake and the sloth.

I'll let you know how I get on.
Member
2005 PX150 Serie America
Joined: 02 Nov 2016
Posts: 35
Location: Honolulu Hawaii
Tue Jun 06, 2017 12:40 am quote
Please let us know how it works. I would like to upgrade my carb aswell.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Sun Jun 11, 2017 7:51 pm quote
Got a box of goodies delivered on Thursday from SIP.

So that included:

Pwk carb

MRP intake

Pilot jet kit

Main jet kit

Oil hole plug

Longer Throttle inner and outer

Ram air filter

Rubber connection hose from intake to carb.

NOTES:
-Still waiting on snake head and sloth.
-Best to order second throttle cable or use old one and order specific choke plunger to run alternate carb choke. Will order as my sketchy setup is not worth talking about and could pop off any moment
-I had an old Keihin pe30 that has the cable choke so used that.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Sun Jun 11, 2017 8:15 pm quote
Oh also needed a smaller diameter fuel line.

As the Keihin fuel line is smaller than the SI.

I went with 1/4 inch - 6mm

Haven't popped it on yet so I'll let you know if I blew the sizing.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 15, 2017 2:41 am quote
All good on the fuel line.

Parcel just updated for the sloth and snake head. Spent the last six days sitting in Germany. So bit of a delay.

Just hooked up the throttle then with the cable out the top for now just to see if it runs.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 15, 2017 2:42 am quote
Carb attached

IMG_1795.JPG

Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 15, 2017 2:43 am quote
Intake

IMG_1797.JPG

Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 15, 2017 2:53 am quote
Oh the idle adjuster is almost impossible to turn.

But the mix screw is pretty good.
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: 8055
Location: Victoria, Australia
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Thu Jun 15, 2017 7:19 pm quote
Just ordered.

Cheers
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Tue Jun 20, 2017 9:26 pm quote
Ok,

Little update.

Still waiting on the snake head and sloth. Hopefully tomorrow or Friday.

But I have been riding it around getting used to it and jetting it.

So far my jetting is:

Main:140
Pilot/Idle: 50
Needle JJH
Clip: 2 (actually haven't changed that so just guessing its on that)

So it feels straight away like its got way more power. Obviously haven't fully dialled in the jetting but definitely a must do if your feeling itchy and like playing with jetting.

It floods occasionally when I come to a stop I think the pilot jet is to rich.
Also hangs when in neutral and blipping the throttle. Hopefully do a quick leak down test on the weekend to rule that out.

It is a bit jerky when rolling down hills in gear might also be the pilot jet.

The Quick action throttle will definitely help as it is a bit of a stretch to get to full.

Could also dremel away some of the intake hole on the engine casings as the new intake hole is bigger than the current hole by a good 3mm in each corner. Next time the engine is out.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2575
Location: London UK
Tue Jun 20, 2017 11:20 pm quote
Sounds too me like your atomiser might be too big.
Ossessionato
1979 P150X, 1983 P200E, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 2143
Location: Veria, Greece
Wed Jun 21, 2017 12:42 am quote
I am running a 132 main 40 pilot JJH 2nd clip and 1&1/2 turns on the mixture screw. Polini PWK 30 on a Malossi 221 engine. What's your setup??
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Wed Jun 21, 2017 2:23 am quote
SaFiS wrote:
I am running a 132 main 40 pilot JJH 2nd clip and 1&1/2 turns on the mixture screw. Polini PWK 30 on a Malossi 221 engine. What's your setup??
Malossi 210 sport
Sip JL Evo
Cut crank
Lightened flywheel

But yeah it seems that the pilot is too big. I just thought it would bog so much but it takes off fine.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Wed Jun 21, 2017 11:16 pm quote
Why has everything got to be so hard.

Got the sloth and the snake head on there. Went on easy. No trouble there.

Went for a spin came back. Noticed it hunting a bit too much. Checked the carb. Intake was loose.

Stripped the casing bolt hole for the intake.

Now I gotta helicoil it back. So I gotta learn how to heli coil too
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: 8055
Location: Victoria, Australia
Thu Jun 22, 2017 4:44 am quote
What a bastard. I hate the feeling when something like that happens.
Guess you could try tapping an M8 thread before going to all the trouble of a helicoil?
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Fri Jun 23, 2017 3:16 am quote
All is well again.

I ended up getting an m6 helicoil setup from Bunnings and ended up getting it to all hold in there. M7 kits are much harder to get locally. But I definitely got it all wrong when I measured it as m6.

I had an m6 screw to put in so it is in nice and tight. Hopefully the last time I have to deal with that.

Changed the pilot to a 42 at 1.5 turns out.

Runs like a dream. Obviously helps without an air leak messing with things and making the revs hang causing me to think it was lean.

But power increase is exactly what I wanted. Front wheel lifts in 1st and the sloth is 0-full in a few centimetres.

Thanks for the links to the snakehead and sloth. Definitely worth putting on if you go down this route.

Jetting so far has been relatively easy. Still waiting on the idle screw to make things easier.

It gets an A+ from me. I would recommend this setup.

Thanks for all the help and recommendations.
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Fri Jun 23, 2017 3:17 am quote
Snake head

IMG_1880.JPG

Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Fri Jun 23, 2017 3:25 am quote
Dirty old sloth.

Lining those holes up for the R clip was not the funnest job ever.

IMG_1876.JPG

Hooked
PX 200
Joined: 25 May 2016
Posts: 101

Wed Jan 13, 2021 8:02 am quote
knoxy_7 wrote:
All is well again.

I ended up getting an m6 helicoil setup from Bunnings and ended up getting it to all hold in there. M7 kits are much harder to get locally. But I definitely got it all wrong when I measured it as m6.

I had an m6 screw to put in so it is in nice and tight. Hopefully the last time I have to deal with that.

Changed the pilot to a 42 at 1.5 turns out.

Runs like a dream. Obviously helps without an air leak messing with things and making the revs hang causing me to think it was lean.

But power increase is exactly what I wanted. Front wheel lifts in 1st and the sloth is 0-full in a few centimetres.

Thanks for the links to the snakehead and sloth. Definitely worth putting on if you go down this route.

Jetting so far has been relatively easy. Still waiting on the idle screw to make things easier.

It gets an A+ from me. I would recommend this setup.

Thanks for all the help and recommendations.
Did you end up keeping the 42 pilot?
Hooked
'98 Px200e
Joined: 14 Jul 2013
Posts: 342
Location: Sydney, Australia
Fri Jan 15, 2021 4:23 am quote
Yeah Iím pretty sure I never changed anything after setting it up.

Iíll be pulling it apart in the coming months to go over it all.

Cheers
Hooked
PX 200
Joined: 25 May 2016
Posts: 101

Sat Jan 16, 2021 8:37 am quote
knoxy_7 wrote:
Yeah Iím pretty sure I never changed anything after setting it up.

Iíll be pulling it apart in the coming months to go over it all.

Cheers
Yeah Iím using a similar setup and Iíve ended up with a 38pilot, 3 turns out... so I canít imagine going bigger on the pilot jet...
Hooked
PX 200
Joined: 25 May 2016
Posts: 101

Mon Jan 25, 2021 9:46 am quote
So weirdly enough I have ended up with a 42 pilot jet ( and a surprising 3turns out) after trying everything from 32, 35, 38, 40... adjusting the air mix screw 1.5 turns all the way out to 4 turns out and riding in circles for about 4 days and looking for the best throttle response and no stalling...

I have the idle speed screw (controlling the height of the throttle slide) a little more open than Iíd like... but it seems to be happiest, no bogging or taking forever to drop back to idle revs...

I have a feeling my jets arenít accurate and my carb air mix screw might be damaged... 3 turns out is a lot... but I am at sea level...
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