OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
I have three performance issues that may or may not be related and I'm hoping that someone here will be able to clarify. I'm riding a stock 1980 P200e

1. If I am cruising at a steady speed and then reduce the throttle quickly for a few moments and then speed up again, there is a hesitation before the throttle kicks in again... almost as though the engine is not firing for a couple of beats.
2. When shifting gears I customarily pull the clutch lever and back off the throttle simultaneously however with this scooter instead of the engine speed dropping during the shift it actually speeds up for a moment while the clutch is disengaged. If I close the throttle just before I disengage the clutch, then the engine doesn't rev up during the shift.
3. When the engine is cold, it usually starts in one or two kicks, however when it has been running for a while and I stop for just a few minutes (turn off the ignition, turn off the fuel tap) then it usually takes 5-6 kicks to get started again. Often it will fire once or twice but not start for a number of kicks. It seems to be better if I start it while the tap is still closed.

I've learned a lot by reading this forum so my (semi) educated guess is that I have an slow-responding throttle and that I'm flooding something somewhere. Does that make sense and what else might be causing these problems? Might all three issues be caused by the same problem? It's more of an annoyance than a problem but if it's a simple adjustment, I'd like to fix it.

This scoot is a recent acquisition for me and has a new top end and a rebuilt carburetor. I've just started riding it again now that the weather is better.
UTC

Addicted
SS208, SX250 , RD's and a K1300s and an RZ350 and TZR250
Joined: UTC
Posts: 567
 
Addicted
SS208, SX250 , RD's and a K1300s and an RZ350 and TZR250
Joined: UTC
Posts: 567
UTC quote
Make sure the fuel line isn't pinched, that fuel flows freely and rebuild the carb... One of those should fix whatever evils were inherited from the previous owner...!
@sfvsr avatar
UTC

Ossessionato
a lambretta or two
Joined: UTC
Posts: 3724
Location: San Francisco
 
Ossessionato
@sfvsr avatar
a lambretta or two
Joined: UTC
Posts: 3724
Location: San Francisco
UTC quote
Sounds like an atomiser problem.
@ginch avatar
UTC

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8595
Location: Victoria, Australia
 
Veni, Vidi, Posti
@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8595
Location: Victoria, Australia
UTC quote
Re: Gas problems
Fatbear5 wrote:
3. When the engine is cold, it usually starts in one or two kicks, however when it has been running for a while and I stop for just a few minutes (turn off the ignition, turn off the fuel tap) then it usually takes 5-6 kicks to get started again. Often it will fire once or twice but not start for a number of kicks. It seems to be better if I start it while the tap is still closed.
Sounds very much like flooding... mine would do that and only ever start [hot] with fuel turned off until I replaced the needle and seat.
@drona avatar
UTC

Molto Verboso
59 Vespa, 65 Vespa, 66 Vespa, 57 Vespa
Joined: UTC
Posts: 1322
Location: Portland Oregon
 
Molto Verboso
@drona avatar
59 Vespa, 65 Vespa, 66 Vespa, 57 Vespa
Joined: UTC
Posts: 1322
Location: Portland Oregon
UTC quote
Can you post here what carb you have along with the jet sizes?
Where is your air/fuel screw set at?
OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
I'm using the stock Dellorto carb that came with the bike, probably 20/24 and I believe that the mix screw is set at 1 and a half turns.

I have no idea about the jet size. I've never messed with them and know very little about them. When I rebuilt the carburetor I just reinstalled the ones that were already there. I would guess that jet sizes are stamped into the jet itself but where would I look for that information?

Thanks
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 90 V5N 50, 01 ET2, 2015 HD Road Glide Special
Joined: UTC
Posts: 5073
Location: Oceanside, CA
 
Veni, Vidi, Posti
@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 90 V5N 50, 01 ET2, 2015 HD Road Glide Special
Joined: UTC
Posts: 5073
Location: Oceanside, CA
UTC quote
The jets have numbers stamped into the brass. Read off what you have. I'm curious to find out.

Scooterhelp has a list of stock jetting numbers halfway down the page. Your numbers should match or be real close.
http://scooterhelp.com/scooters/VSX1T.p200.html
UTC

Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
UTC quote
You should have 160 AC, BE3 mixer, 116 main jets. Along with 55/160 idle jet and 60 starter.
OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
I did some checking and found that I have the Dellorto 24/24 carb with a 160 pilot jet and a 116 main jet (if I read them right). I thought there was a third jet but I can't find it... unless it's the tall one that extends up out of the carb box cover on the left.

Do those jet sizes sound right?
Forum member supplied image with no explanatory text
OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
Didn't see your comment Tierney but the 116 main jet seems right on target. I don't know what an AC, BE3 mixer is but if it is what some people call a Pilot Jet then I'm good with my 160 reading as well.

Still don't know where the starter and idle jets are though. Is one of those the very tall adjuster?
UTC

Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
UTC quote
Big jet is the one you said was 160 - which is the air corrector and that is the top of the three parts(jet stack). The 116 was the main jet at the bottom. The mixer connects these two together - and it should be a BE3. You may need a magnifying glass to see the markings. The smaller jet next to the main stack is your idle jet - this should be 55/160. The starter jet is buried under float assembly - you access this by removing two hex head screws and that should be a 60.
UTC

Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
UTC quote
The tall screw with the spring on it is your idle set screw and has nothing to do with the jets. It sets your slide that you see when you look down the venturi. That is, it is what keeps the slide from completely closing and by screwing in or out, allows you to set your idle speed.
OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
No wonder I couldn't find the damned thing... I didn't know the starter jet was down in the bowels of the carburetor. Thanks,.. now I know where to look.

Yeah, I didn't really think that the Idle Set Screw was one of the jets but when I couldn't find the starter jet, I really began to wonder if that was possible. Glad to know I'm not totally crazy after all. I'll look in to the mixer the next time I'm playing with it.

Thanks for the info
OP
@fatbear5 avatar
UTC

Molto Verboso
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
 
Molto Verboso
@fatbear5 avatar
1977 P200, 1980 P200
Joined: UTC
Posts: 1214
Location: Fresno, CA
UTC quote
I have an update on my gas problem... and a possible answer... but before I go blindly tearing into things, I wanted to run it by the Forum members.

This afternoon, after sitting for about 7 hours, my P200 started on the first kick and ran beautifully for about a mile or two when I stopped for gas. After filling up, the engine wouldn't start. Previously, after stopping for a few minutes, it was always difficult to start with the engine firing one or two times but not actually starting. Eventually though, after half a dozen kicks or so, it would start up and run beautifully (other than the problems stated in earlier posts on this thread) until the next time I stopped.

Today, after stopping for gas, the engine would not start at all. I even changed spark plugs and used starting fluid but couldn't get a single fire. After pushing the scoot home, I opened the carb box, removed the air cleaner and found a large puddle of gasoline in the carb box. .. probably a quarter of an inch deep. I removed the rubber stopper, drained the gas, and after a few kicks, (with gas spraying out of the carb throat) the engine started right up again.

Now I know WHAT happened but not WHY. I'm thinking, perhaps a problem with the carburetor float?... maybe getting stuck?. The carburetor was recently rebuilt but I have little confidence in the guy who rebuilt it (me) and I'm wondering if the float was replaced incorrectly.

I also replaced the fuel tap and I know that they sometimes fail so I'm wondering if I should check out that too.

I'm going to work on it over the weekend so I'd welcome any observations or recommendations that any one might have.
@socalguy avatar
UTC

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7070
Location: So Cal
 
bodgemaster
@socalguy avatar
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7070
Location: So Cal
UTC quote
Your carb's flooding, and flooding is almost always the result of a worn or stuck float needle.
@primavera130 avatar
UTC

Hooked
Vespa P200, Primavera 130, VNA200, Italjet Pack-a-Way Moped, Ciao etc
Joined: UTC
Posts: 322
Location: Humboldt County, California
 
Hooked
@primavera130 avatar
Vespa P200, Primavera 130, VNA200, Italjet Pack-a-Way Moped, Ciao etc
Joined: UTC
Posts: 322
Location: Humboldt County, California
UTC quote
top of your float bowl
A few things could be happening. One or both of the float bowl screws could be loose, the "banjo bolt" that connects the fuel line to the carb could be loose or missing a gasket.

I had this happen on a 200 mile run between home and Sacramento. My buddy picked me up in a truck. Figured it out after i got there. Could've been a five minute job.

The hard starting may be separate though.
UTC

Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 6485
Location: Tega Cay, SC
UTC quote
Check all the screws in the carb box area for proper torque. On my Super, the collar screws would loosen up every few months. The two screws that hold the float assembly together should have a wavy washer on there and the bolt that secures the banjo may be loosening up as well.
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