Appreciate the advice about a possibly oversized main jet, but
there's no way that can be the problem. This is the factory
original jet, and the scooter ran well in the past.
That said, after some tinkering this weekend, I finally got the
Spree running pretty good. Starts right up, idles strong,
accelerates fairly smoothly, and no more fouling. The bogging
has also stopped, thanks to some Gas Treatment. My only
complaint now, is that since I had a taste of a 35 mph max, I
wish I could still get past my new max of 30 mph. Funny thing,
if I now remove the air filter to try to recreate the 35 mph
scenario, I have nothing but problems. Rough idle/running,
bogging, etc. I even have problems if I leave the airbox open a
Are there any simple adjustments I can try to get back that last 5 mph?
Date: Mon, 11 Sep 2000 00:50:17 -0700
From: email@example.com Add To Address Book
To: ScooterBoi@moped2.org, firstname.lastname@example.org
Subject: RE: Inconsistent '85 Spree
The air screws on the carb only come into effect at low rpm. I.e at idle,
or 1/4 gas.
It sounds to me like you have a main jet that's way too big. The main jet
only comes into full effect when the throttle is raised all the way up,
which could explain why the engine is bogging at higher speeds. Also, if
it runs better with the air filter taken off, it means a leaner mixture
(which is the effect of removing the filter) works better. Better yet, the
clogged spark plug/backfiring. That's really a dead giveaway of having too
large main jet.
Try replacing the main jet with a smaller one. Buy several of them, and
work your way downwards in size. Lets say you have a 54 now, you would then
try a 52, then a 50 etc. Be careful not to underdimension the jet though.
It could (will) damage your engine, as it will not get a proper cooling
with a too lean fuel mixture.
When testing the jet, find a long road thats level, and without potholes.
Mount a new spark plug, and warm up the engine. Run the length of the road
at full throttle, then cut the engine dead while its at a high
rpm (<-IMPORTANT)Remove the plug and read it. The plugs'
insulator nose should be sandy brown, with little or no pitting
on either the nose and plug housing. If the insulator nose is
shiny white/yellow, with pitting both on the nose and on the
housing, you have a main jet that's too small. If the plug is
clogged with soot and oil, you have a main jet that's too big.
> -----Original Message-----
> From: ScooterBoi@moped2.org [mailto:ScooterBoi@moped2.org]
> Sent: Saturday, September 09, 2000 12:50 AM
> To: email@example.com
> Subject: Inconsistent '85 Spree
> > My '85 Spree was bogging right at the 25 mph mark. Ran strong
up to 25,then it would hickup. But after some random tinkering
with the carb, and REMOVING the dirty air filter, the thing shot
up to 35 mph. > But now after I put in a brand new air filter, I
can USUALLY max around 32-33 mph, but occasionally still
> My questions: 1)Are the screws (air/fuel) on the carb just for
idle adjustments, or do they affect overall performance? 2) I
occasionally get a backfire around 25 mph, what can this be a
symptom of? 3)Should I just be happy with the 32-33 max WITH air
filter, or should I eventually be able to get back up to 35 mph
like i was getting WITHOUT the filter? 4)The Scooter > usually
starts/idles strong, but sometimes after idling for a 5-10
minutes,it will sputter and die, how come? > > I also notice my
plug fouls constantly. Every time I check it, it's covered in
black. It's brand new, and I clean it each time, but should I
buy another one? What would cause this?