20/20 Carb in a P200e?????!!!!!!
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Molto Verboso
Footsie?
Joined: 04 Sep 2009
Posts: 1061
Location: Los Angeles
Wed Nov 18, 2009 5:36 pm quote
OK -

So I've been slowly getting to my winter project P200E - just starting to tune up the engine. It's been flooding so I opened up the carb to replace the float and needle. Much to my suprise, the carb is a Dellorto 20/20. I thought P200s had a 24/24. I bought this bike from the orig. owner and he kept everything stock, so it must have come this way. Seems like too small a carb for the 200e engine. Anyone else ever heard of this on a P200?
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8695
Location: The state of insanity, SoCal
Wed Nov 18, 2009 5:42 pm quote
20/20 cam stock on the later P2's to help meet stricter smog laws.

a 20 is okay for a stock 200, but a 24 really wakes it up.

if you upgrade to the 24, be sure to open up the carb box as well to match.

best,
-greasy
Molto Verboso
Footsie?
Joined: 04 Sep 2009
Posts: 1061
Location: Los Angeles
Wed Nov 18, 2009 6:06 pm quote
greasy125 wrote:
20/20 cam stock on the later P2's to help meet stricter smog laws.
Ah, that makes sense. It is an '81.
greasy125 wrote:
if you upgrade to the 24, be sure to open up the carb box as well to match.

Appreciate the advice - what exactly needs to be "opened up" in the carb box? I thought that the 20 and 24 used the same carb box...
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8695
Location: The state of insanity, SoCal
Wed Nov 18, 2009 6:36 pm quote
littlebluedisaster wrote:
Appreciate the advice - what exactly needs to be "opened up" in the carb box? I thought that the 20 and 24 used the same carb box...
the box is the same, it's the orfice of the intake that is smaller.

just remove it, use the 24 gasket as a pattern, and dremel it open.

it'll work without opening it, but it just won't be optimal.

best,
-greasy
Molto Verboso
Footsie?
Joined: 04 Sep 2009
Posts: 1061
Location: Los Angeles
Wed Nov 18, 2009 10:28 pm quote
Got it - thanks!
Enthusiast
'81 Vespa P200 E, '76 150 Sprint Veloce
Joined: 16 Jul 2008
Posts: 85
Location: Santa Monica, CA
Thu Nov 19, 2009 1:57 am quote
Mine had 20/20 in it and I was wondering why I was getting passed on the straight away...Thanks to the advice on the forum, i switched it to 24/24 and it has made a huge difference.
Hooked
2005 Px 150 canadian series
Joined: 16 Sep 2007
Posts: 106
Location: New Westminster,B.C. Canada
Mon Nov 23, 2009 1:09 am quote
Switch to a 24/24 minium, with all the matching original parts, that is the way it was originally designed...
Addicted
1980 P200e, 1956 ACMA, 1979 P200e, 1974 Ciao
Joined: 04 Jun 2009
Posts: 766
Location: Ithaca, NY
Mon Nov 23, 2009 8:22 am quote
Yes, you'll definitely want to open up the hole in the air box. I bought a 24/24 carb and was astonished at how small the airbox opening was compared to the carburetor.

I have before and after pictures, somewhere, if you want some pictures to help you out.

Mike
Member
P200E, BV 350
Joined: 27 Oct 2008
Posts: 47
Location: Austin, Tx
Mon Nov 23, 2009 11:43 am quote
Hojo, Can you post the photos, if you get a chance. I am considering changing out my carb but am a little in the dark on the details.
Thx
Molto Verboso
Footsie?
Joined: 04 Sep 2009
Posts: 1061
Location: Los Angeles
Mon Nov 23, 2009 12:15 pm quote
eric_aus wrote:
Hojo, Can you post the photos, if you get a chance. I am considering changing out my carb but am a little in the dark on the details.
Thx
+1

I get the idea, but a photo always helps!
Addicted
1980 P200e, 1956 ACMA, 1979 P200e, 1974 Ciao
Joined: 04 Jun 2009
Posts: 766
Location: Ithaca, NY
Mon Nov 23, 2009 12:43 pm quote
Here are some photos from when I drilled out my airbox:


Here is my airbox and 24/24 carburetor before modification


Here's the airbox, midway through the conversion. I opened up the hole a bit more after this picture, but the last picture didn't come out well.

Member
P200E, BV 350
Joined: 27 Oct 2008
Posts: 47
Location: Austin, Tx
Mon Nov 23, 2009 1:13 pm quote
+5 for the pics.
Do the holes need to "kind of" match or do they need to be pretty close?
Hooked
81 - P200E
Joined: 07 Jan 2009
Posts: 305
Location: St Louis
Mon Nov 23, 2009 1:18 pm quote
hojo1690 wrote:
Here are some photos from when I drilled out my airbox:
Did you notice a large difference after you drilled out the airbox? I was thinking of doing this over the winter "no-ride due to weather" times.
Enthusiast
2008 Genuine Stella with P200e motor
Joined: 10 Mar 2009
Posts: 68
Location: Oklahoma
Mon Nov 23, 2009 1:19 pm quote
I would guess that you'd want to get them as close as possible and smooth the edges.

I don't know how much air passes thru while riding but I'd think it would be more efficient that way... having the 2 be as close as possible.
Addicted
1980 P200e, 1956 ACMA, 1979 P200e, 1974 Ciao
Joined: 04 Jun 2009
Posts: 766
Location: Ithaca, NY
Mon Nov 23, 2009 1:59 pm quote
Honestly, I didn't note a large difference with any one change, but it's MUCH better than it was when I started.. I made a lot of incremental tweaks over time. I put in a sito+ pipe, the bigger 24/24 carburetor, up-jetted to 118, drilled out the airbox, drilled the air filter, replaced the CDI, spark plug, wire and cap.

The net of all that is that the bike now reliably starts on the 3rd kick or so when ice cold, and runs very nicely. It'll hold 55-60 MPH on the flat, and will basically keep up with the normal traffic on the hilly rural route that is my daily commute. On the moderate hill out of town (I live about 6 miles outside town), I can maintain about 45 MPH, which is about what most of the cars want to do anyway, even though the posted speed is 55.

Oh, and let's not forget the strawberry scented two-stroke oil. I'm sure that's the biggie!

If I was just putting around in town at 30 mph, I wouldn't recommend the effort and expense of all the mods, but given that the bulk of my commute is 45 MPH or more, they really make it more tolerable and safer (since I have fewer cars climbing up my butt!)

Mike
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