Mon Sep 12, 2022 10:15 am

Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: 27 Oct 2009
Posts: 4983
Location: Sparks, Nevada, USA
 
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: 27 Oct 2009
Posts: 4983
Location: Sparks, Nevada, USA
Mon Sep 12, 2022 10:15 am linkquote
I wonder if the float in the carb bowl is adjusted correctly. The float level is adjusted by bending the little metal tab that closes/opens the needle to keep the fuel level in the bowl from getting too high/low. If the fuel level in the bowl is too high you can end up with a rich condition.

When the scooter is idling, are you seeing black smoke from the exhaust? Does the exhaust smell rich?
Mon Sep 12, 2022 10:19 am

Addicted
S150 '09, Beo 500ie '08
Joined: 14 Aug 2019
Posts: 913
Location: Bermuda
 
Addicted
S150 '09, Beo 500ie '08
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Location: Bermuda
Mon Sep 12, 2022 10:19 am linkquote
Good thought, but he replaced the carb already.
Mon Sep 12, 2022 10:45 am

Member
ET4
Joined: 10 Aug 2022
Posts: 32
Location: Texas
 
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ET4
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Location: Texas
Mon Sep 12, 2022 10:45 am linkquote
caschnd1 wrote:
I wonder if the float in the carb bowl is adjusted correctly. The float level is adjusted by bending the little metal tab that closes/opens the needle to keep the fuel level in the bowl from getting too high/low. If the fuel level in the bowl is too high you can end up with a rich condition.

When the scooter is idling, are you seeing black smoke from the exhaust? Does the exhaust smell rich?
Good thought. Float is good in both carbs.
Mon Sep 12, 2022 1:40 pm

Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: 27 Oct 2009
Posts: 4983
Location: Sparks, Nevada, USA
 
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: 27 Oct 2009
Posts: 4983
Location: Sparks, Nevada, USA
Mon Sep 12, 2022 1:40 pm linkquote
I know you replaced the fuel tap. But check to make sure that the new fuel tap is not leaking fuel into the vaccum hose. I've seen this happen once in the past. The unregulated fuel makes it down the vaccum tube and ends up getting dumped into the intake (bypassing the carburetor).

You've addressed all the most common problems. This one would be really rare, but it's easy enough to check.
Mon Sep 12, 2022 3:49 pm

Member
LX50, P200E
Joined: 15 Jul 2022
Posts: 45
Location: A terrible place to exist outside DC
 
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LX50, P200E
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Location: A terrible place to exist outside DC
Mon Sep 12, 2022 3:49 pm linkquote
Quote:
I know you replaced the fuel tap. But check to make sure that the new fuel tap is not leaking fuel into the vaccum hose. I've seen this happen once in the past. The unregulated fuel makes it down the vaccum tube and ends up getting dumped into the intake (bypassing the carburetor).

You've addressed all the most common problems. This one would be really rare, but it's easy enough to check.
Yeah...
I just re-read page one and there is no indication that you checked the vacuum line to the fuel tap.
There should be no gas coming out of the fuel line when the engine's off.
I know you got fuel out of the float bowl, but if the fuel tap is defective, you're pumping gas after the carb.
Just pop the vacuum line off from the intake....
Pop the fuel line off the carb....
If gas comes out without stopping, the tap is defective.
If no fuel comes out, apply suction to the vacuum line....that opens the tap and gas will flow.
If gas comes out of the vacuum line, the tap is defective.
Tue Sep 13, 2022 5:26 am

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Posts: 32
Location: Texas
 
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Tue Sep 13, 2022 5:26 am linkquote
crossbones wrote:
Yeah...
I just re-read page one and there is no indication that you checked the vacuum line to the fuel tap.
There should be no gas coming out of the fuel line when the engine's off.
I know you got fuel out of the float bowl, but if the fuel tap is defective, you're pumping gas after the carb.
Just pop the vacuum line off from the intake....
Pop the fuel line off the carb....
If gas comes out without stopping, the tap is defective.
If no fuel comes out, apply suction to the vacuum line....that opens the tap and gas will flow.
If gas comes out of the vacuum line, the tap is defective.
I've confirmed the fuel tap is working properly but I have not confirmed there isn't fuel in the vacuum line. I'm moderately confident there isn't as I've had it unplugged enough times that I would have noticed gas by now but I'll take another look.
Tue Sep 13, 2022 8:24 am

Veni, Vidi, Posti
Joined: 22 Oct 2011
Posts: 5151
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: 22 Oct 2011
Posts: 5151
Location: Tega Cay, SC
Tue Sep 13, 2022 8:24 am linkquote
I may have missed it, but did you ever remove rhe rubber intake manifold to check for cracks?
Tue Sep 13, 2022 9:12 am

Hooked
ET2 ZAPC 1600
Joined: 21 May 2022
Posts: 258
Location: UK
 
Hooked
ET2 ZAPC 1600
Joined: 21 May 2022
Posts: 258
Location: UK
Tue Sep 13, 2022 9:12 am linkquote
Gdl4198 wrote:
I've confirmed the fuel tap is working properly but I have not confirmed there isn't fuel in the vacuum line. I'm moderately confident there isn't as I've had it unplugged enough times that I would have noticed gas by now but I'll take another look.
It can happen - saw a Youtube video of a bike actually running off the vacuum line (hoses were accidentally reversed and petcock faulty - this was an ET2 though). Weird, I know!
Tue Sep 13, 2022 9:41 am

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Location: Texas
 
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Tue Sep 13, 2022 9:41 am linkquote
Tierney wrote:
I may have missed it, but did you ever remove rhe rubber intake manifold to check for cracks?
I did. I sprayed the crap out of it with no effect and then removed both sides last weekend to inspect.

The plug suggests running rich. Pic is above if you want to see.
Tue Sep 13, 2022 2:17 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Posts: 11846
Location: The state of insanity, SoCal
Tue Sep 13, 2022 2:17 pm linkquote
that is so odd, it almost sounds like you've got a vacuum leak in there somewhere. did you check the evap lines-- esp. the ones to the carbon canister?

that plug is dark dark. it's almost like you've got a stuck ring or something and it's sucking oil.
Tue Sep 13, 2022 3:29 pm

Member
LX50, P200E
Joined: 15 Jul 2022
Posts: 45
Location: A terrible place to exist outside DC
 
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LX50, P200E
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Location: A terrible place to exist outside DC
Tue Sep 13, 2022 3:29 pm linkquote
Quote:
I've confirmed the fuel tap is working properly but I have not confirmed there isn't fuel in the vacuum line. I'm moderately confident there isn't as I've had it unplugged enough times that I would have noticed gas by now but I'll take another look.
Hi,
(You WILL figure this out...)
How did you confirm that the fuel tap is working?

Your problem is pointing at an over rich situation, barring something exotic, like an ignition issue....
That could be one of several things....but you have to start out with a compression check and eliminate silly fuel/air issues.
(I know it doesn't seem silly right now...)
Tue Sep 13, 2022 5:07 pm

Veni, Vidi, Posti
Joined: 22 Oct 2011
Posts: 5151
Location: Tega Cay, SC
 
Veni, Vidi, Posti
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Tue Sep 13, 2022 5:07 pm linkquote
greasy125 wrote:
that is so odd, it almost sounds like you've got a vacuum leak in there somewhere. did you check the evap lines-- esp. the ones to the carbon canister?

that plug is dark dark. it's almost like you've got a stuck ring or something and it's sucking oil.
All the more reason to get a compression test
Fri Sep 16, 2022 3:54 pm

Member
ET4
Joined: 10 Aug 2022
Posts: 32
Location: Texas
 
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Fri Sep 16, 2022 3:54 pm linkquote
No gas in the vacuum line from the fuel tap.

Compression test around 130 psi.



Fri Sep 16, 2022 4:30 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
Fri Sep 16, 2022 4:30 pm linkquote
is that with or without the decompression lever present, with or without the throttle open?
Fri Sep 16, 2022 4:32 pm

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Location: Texas
 
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Fri Sep 16, 2022 4:32 pm linkquote
Throttle closed, no decompression lever that I'm aware of
Fri Sep 16, 2022 4:35 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
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Fri Sep 16, 2022 4:35 pm linkquote
Gdl4198 wrote:
Throttle closed, no decompression lever that I'm aware of
decompression lever is a counterweight designed into the camshaft/cam drive assembly. don't worry about it for now.

make sure the battery and starter are tip top, throttle open, crank until the gauge stops fluttering. anything under 9 bar and you've got a problem.
Sat Sep 17, 2022 12:31 pm

Member
ET4
Joined: 10 Aug 2022
Posts: 32
Location: Texas
 
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Sat Sep 17, 2022 12:31 pm linkquote
greasy125 wrote:
decompression lever is a counterweight designed into the camshaft/cam drive assembly. don't worry about it for now.

make sure the battery and starter are tip top, throttle open, crank until the gauge stops fluttering. anything under 9 bar and you've got a problem.
Open throttle compression is just under 11 bar
Sat Sep 17, 2022 5:30 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
 
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Sat Sep 17, 2022 5:30 pm linkquote
Gdl4198 wrote:
Open throttle compression is just under 11 bar
well. you've got compression.

here's a shot in the dark- try running it without the gas cap. that's a total shot in the dark.

anyway, there's a red LED in the dash that blinks. when you turn the key to the on position what is the blink sequence?

2ndary questions:
-have you tested the stator?
-what coil did you replace with?
-did you check your plug cap, or have you replaced that as well?
-what type of plug (brand, part number, screw on or molded nipple)
-on the air filter, when you replaced the old one what was its condition like?

is there any service history of the bike? like, has somebody been in the motor or anything like that?
Sun Sep 18, 2022 6:17 am

Member
ET4
Joined: 10 Aug 2022
Posts: 32
Location: Texas
 
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Sun Sep 18, 2022 6:17 am linkquote
greasy125 wrote:
well. you've got compression.

here's a shot in the dark- try running it without the gas cap. that's a total shot in the dark.

anyway, there's a red LED in the dash that blinks. when you turn the key to the on position what is the blink sequence?

2ndary questions:
-have you tested the stator?
-what coil did you replace with?
-did you check your plug cap, or have you replaced that as well?
-what type of plug (brand, part number, screw on or molded nipple)
-on the air filter, when you replaced the old one what was its condition like?

is there any service history of the bike? like, has somebody been in the motor or anything like that?
I'll try the gas cap trick. I think I tried it early in the process but I'll give it another go.

Led - single flash while it's off, turn on the key, light comes on for a second and then goes out. Doesn't come back on

I bought it from an older lady that had it serviced professionally. It only has 1600 miles on it. I don't think anyone has been in it before

Haven't touched the stator. Iridium plug from scooters west. It has a screw on end Same for coil. Oem replacement I believe.

The air filter was totally broken down when I got it. It was intact so I don't think anything was ingested but a possibility.
Sun Sep 18, 2022 3:47 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
Sun Sep 18, 2022 3:47 pm linkquote
I'd have a look and make sure that there isn't any air filter detritus in the intake port or hanging the valves. it's unlikely, but a possibility.

when you checked the valves, how did the cam look? was there any scoring or odd signs on the surface?

given the state of the plug, it's almost as if the valve seals are shot and it's sucking oil.

when it's running is there any perceptible smoke? if so what color?

have you checked the exhaust? is it obstructed in any way? like, maybe a mouse built a house in there?

it's just so interesting. you have compression, you have fuel, and you have spark. it just won't go.
Mon Sep 19, 2022 8:03 am

Member
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Location: Texas
 
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Mon Sep 19, 2022 8:03 am linkquote
i keep thinking about that air filter too. I've looked down as far as I can see w/o finding anything.

the cam looked good to me. The thing doesn't smoke a bit. It starts right up. Idles like a dream. its the craziest thing. If it ride it, it won't go over 20mph on the flat.

Exhaust has plenty of flow. I don't have a camera to run through it but its a nice solid exhaust when you hold your hand in front of it.

I'm beside myself. My wife is starting to make fun of me for not having it going yet! She's asking if I've finally met my match
Tue Sep 20, 2022 6:19 am

Member
LX150
Joined: 28 Sep 2020
Posts: 5
Location: Charlotte, NC
 
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LX150
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Location: Charlotte, NC
Tue Sep 20, 2022 6:19 am linkquote
Hey there - I'm having a very similar experience with an '07 LX150, although I can get a bit better than 20mph, the engine bogs down/loses power with any throttle over 3/4 open. If I hold it wide open, it bucks and surges a bit and slowly accelerates, and gradually improves as I get over 30mph and the revs increase. I've replaced just about everything except the CDI and the stator. I'm going to make a separate post about mine but I just thought I'd pop in and say you're not alone fighting a mystery
Tue Sep 20, 2022 6:19 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Tue Sep 20, 2022 6:19 pm linkquote
per the other thread: 2007 LX150 Aggravation - Fuel, Air, Spark... and magic?

something to have a quick look at!

good luck!
Wed Sep 28, 2022 11:57 am

Member
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Wed Sep 28, 2022 11:57 am linkquote
Latest update. I was indeed missing the airbox seal. It obviously helped but didn't get it to 50 or 60 mph. I'm up to about 25mph. Gas cap loosening had no noticeable impact.

I will note the air screw has very little effect from 0 turns out to 2+ turns out. A small increase at about .5 turns out and it all but quits at 2.5 to 3 turns out.

Have not removed the head to look at the intake. Trying to find a borescope to use before I go there.
Wed Sep 28, 2022 2:25 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Posts: 11846
Location: The state of insanity, SoCal
Wed Sep 28, 2022 2:25 pm linkquote
man, that's confounding.

interesting on the A/F miss screw. it should die all the way seated, at .5 out it will run but be noticeably hunting on idle, right around 2~3 is where it'll pick right up and you'll notice it feels "right" beyond that it'll get all choppy and boggy.

anyway, at this point I don't have much left in the bag of tricks. I'd say if you can get your hands on CDI to test I'd go that route or splash the cash for one-- the non-immobilizer units aren't an arm and a leg and you don't have to re-key.

btw, I don't remember if asked and answered: how many miles does this thing have on it?
Wed Sep 28, 2022 5:12 pm

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Location: Texas
 
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Wed Sep 28, 2022 5:12 pm linkquote
1650 ish miles. Next to none in my expectation/understanding.

Maybe there is something down the intake blocking the intake valve? I have no idea. I'll be glad when I find it though...

Thanks for the suggestions along the way.
Wed Sep 28, 2022 5:24 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Posts: 11846
Location: The state of insanity, SoCal
Wed Sep 28, 2022 5:24 pm linkquote
yeah man, at this point I'd suggest going back over all the work and double check to see if maybe you inadvertently missed something-- which is a smart move and doesn't cost you anything but time.

then I'd try a CDI before tearing stuff apart. at least with a CDI you don't have to pull the engine! 10min and you'd have an answer!
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