Setting carb on a Vespa?
markk
think I want to try one out, as well as cleaning the exhaust.
Thanks to all!
Slinky wrote:
>
> might seem stupid, but have you tried adjusting the throttle stop screw. If
> you don't know where that is, that off the engine side panel, there'a a
> couple of screws in the airbox cover. The throttle stop is the one that
> sticks out a bit. Turning it clockwise will speed up the idle speed (by
> opening the throttle slightly), other way slows it down.
>
> Failing that, try the mixture screw on the back of the carb case. Do you
> know how to set the mixture? If not post the question because I don't want
> to waste time writing it all down.
>
> Or could be your exhaust clogged up, when was the last time you cleaned the
> exhaust?
>
> All else fails, time to check the carb etc, but this involves more work, so
> hopefully it isn't that.
> markk wrote in message <37E18FB8...@halcyon.com>...
> >Two days ago all was well. Yesterday I start up the 74 Rally 200 E and the
> idle is very labored.
> >Dumm...Dummm...Dummm (instead of dumDUMdumdumm...). Thought it was the
> cool weather, but today it's
> >warm and no change. Checked and cleaned the 1.5 month old plug that I got
> with the new HT Coil, the
> >plug was mostly black (rich mixture?). So I cleaned it and thought it
> should at least run better
> >for a little while, but no luck there either.
> >
> >Still a labored idle and it sometimes stalls. Wants to start up right
> away, but it won't really
> >keep going. Crank on the gas and SOMETIMES it revs the engine.
> >
> >Rich mix? Dirty carb?
> >
> >HELP! How to check and fix?
> >
> >Thanks
> >markk
occupant
or smaller one. there is a screw i believe for fine adjustments, but i've never had to use it.
that screw is the reason for the hole in the back of the airbox on most vespas.
Slinky
Start up the bike and let it idle. Sorry, you will have removed the engine
panel first! Now turn the throttle stop screw until you get the slowest
possible idle, a reliable idle without stalling (the throttle stop screw is
the centre one on the air box). You might want to make a note of its
originimal position before messing around, to do so, count the turns
clockwise until it is lightly seated).
Back to setting the mixture: when you have the slowest acceptable idle, you
will need to turn the mixture screw. This is located on the back of the
airbox between the crankcase and the frame. It is probably protected by a
small rubber grommet. Prise out the grommet and there it is. Count the
turns clockwise until it is lightly seated and make a note of the original
position. Make sure you write it down, because you will forget, no matter
how hard you try.
Return the mixture screw to its original position. Now turn the screw
anti-clockwise by quarter turn at a time, listening carefully to the speed
of the engine. Return the screw to the original position again, and do the
same thing but turn clockwise. The setting you want is the fastest engine
speed possible, or highest revs. You can make fine adjustments with the
throttle stop screw. You will probably find that the mixture screw is set
about 1 1/2 turns outwards from seated. Basically, screwing the screw in
makes the mixture richer, turning it out weakens it.
If this doesn't work, try looking at your exhaust. Even if this isn't the
problem, you should clean your exhaust once a year as it is:
You can get rid of carbon build up around the opening with a piece of metal,
screwdriver or whatever. If yu want to give it a good clean do as follows:
make up as strong a mixture of caustic soda. Make sure you follow the
safety instructions, its powerful stuff. Now bung up one end of the exhaust
(this is after unbolting it from the engine), or stand it up on an outdoor
drain with the ports at the top (all of this should be done outside by the
way), Fill up the exhaust with the caustic soda solution, wearing gloves
and glasses (even sun glasses). Leave over night. Here's one I prepared
earlier: when you empty it out, you should see all kinds of shit dissolved
away, and your scoot will breathe more easily. If this does't work, you can
repeat, but you might as well buy a new exhaust (plenty of shop on the web
even in the UK who will mailorder you a P200 exhaust: try doing a search
for SIP scootershop in Germany, or Beedspeed in the UK).
Have you decarbonised the engine recently?
Finally, a black oily plug (as opposed to black sooty) is indication of a
badly worn engine, so you might have to take it to a shop for a rebuild.
Hope this helps, if you have any other questions, please post them, I am so
bored at work at the moment that I have nothing better to do than post long
replies to NG's.
Cheers
markk wrote in message <37E3B5AF...@halcyon.com>...