Tuning Tips - P200
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Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3080
Location: Lake Worth, FL
Tue May 17, 2011 9:33 pm quote
Just bolted on a new stock top end and a new throttle cable. Starts wonderfully, but I could use some tips on how to tune it.

Right now I'm running premix, and I'm trying to get it to idle lower than it is without bogging out. How open should the throttle slide be at idle?
Addicted
Vespa GL Touring 180, Vespa GL 225, Vespa PX 200 Sahara Edition
Joined: 21 Jan 2011
Posts: 572
Location: Norway
Wed May 18, 2011 12:58 am quote
Re: Tuning Tips - P200
TravisNJ wrote:
Just bolted on a new stock top end and a new throttle cable. Starts wonderfully, but I could use some tips on how to tune it.

Right now I'm running premix, and I'm trying to get it to idle lower than it is without bogging out. How open should the throttle slide be at idle?
Why do you want to do that? If it idles ok, leave it. If you lower the idle speed enough it will bog out.

It'll idle a little slower when cold and a little faster when warm.
Ossessionato
T5 Pole Position, T for thoroughbred
Joined: 07 Oct 2010
Posts: 3810
Location: Dublin
Wed May 18, 2011 1:06 am quote
as long as it isnt ticking over stupid fast let it be. the throttle slide should be shut at idle.
Ossessionato
vba,, vglb,
Joined: 08 Apr 2009
Posts: 3411
Location: west aus
Wed May 18, 2011 2:59 am quote
jackson85 wrote:
as long as it isnt ticking over stupid fast let it be. the throttle slide should be shut at idle.
eggsackery,, if its idln too fast is the throttle cable outer too long
Addicted
1980 P200e, 1956 ACMA, 1979 P200e, 1974 Ciao
Joined: 04 Jun 2009
Posts: 766
Location: Ithaca, NY
Wed May 18, 2011 3:41 am quote
Re: Tuning Tips - P200
TravisNJ wrote:
Just bolted on a new stock top end and a new throttle cable. Starts wonderfully, but I could use some tips on how to tune it.

Right now I'm running premix, and I'm trying to get it to idle lower than it is without bogging out. How open should the throttle slide be at idle?
I'm not sure if you're asking about the idle screw setting, or if you're observing that the idle slide seems more open than it should be at idle. At idle, the slide should be as far left as it wants to move by itself, IE: not under tension from the throttle cable. You just adjust how open the slide is with the idle screw. If it looks like the throttle cable is holding it open, you need to make some kind of cable adjustment.

In terms of "how fast" it should be at idle, I concur with what was said above. Make it as fast as necessary so it's not stalling all the time.

Mike
Banned
'80 p200 '63 li190
Joined: 15 Mar 2011
Posts: 441
Location: Philadelphia & Brooklyn
Wed May 18, 2011 4:28 am quote
hows it riding? youd basically be riding it around the block like twice, and then making sure that the idle comes back to a setting that you're looking to have it at. and making tiny adjustments until you get that desired effect.

the unpublished tuning guide: http://www.vespamaintenance.com/fuel/carbtune/ but since you're running premix it makes the whole mix screw thing irrelevant. if the idles still a bit too high for your liking, and as long as the idle speed adjusts when you turn the idle stop screw, mess with it in your garage, then give it a go around the block, and bring it back to see if the idle changed at all. tunings a relatively long process.
Ossessionato
07 GTS250, Several Lambrettas
Joined: 25 Apr 2007
Posts: 2467
Location: Raleigh, NC
Wed May 18, 2011 4:57 am quote
What?!? You might want to re-think this one.

Pre-mix or not, does not negate the use of the air/fuel mixture adjustment. That adjustment is entirely relevant, mostly at idle, but though-out the entire throttle range as well.
vespretta wrote:
h... but since you're running premix it makes the whole mix screw thing irrelevant. i...
Ossessionato
1970 Vespa Rally 180
Joined: 04 Dec 2008
Posts: 4117
Location: Denton Tx.
Wed May 18, 2011 6:00 am quote
starreem wrote:
What?!? You might want to re-think this one.

Pre-mix or not, does not negate the use of the air/fuel mixture adjustment. That adjustment is entirely relevant, mostly at idle, but though-out the entire throttle range as well.
vespretta wrote:
h... but since you're running premix it makes the whole mix screw thing irrelevant. i...
+1. the mix screw is very important and can lead to disaster if not set properly. you should do some more research before going any further. vespahelp.com and vespamaintenance.com
Molto Verboso
px200
Joined: 13 Apr 2010
Posts: 1132
Location: london
Wed May 18, 2011 6:02 am quote
+2 on the mixture screw its relating to fuel/air and not fuel/oil.

Grumpy
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