85' Spree fires up then dies

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Therider94
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85' Spree fires up then dies

Post by Therider94 »

I have an 85' Spree that I have been working on getting running. I have cleaned the carb, replaced the lines, and have a new spark plug.

I can get the spree to fire up and then it immediately dies. The plug seems to be wet, though I have adjusted the mixture screw in both directions with the same results. Any help would be appreciated!
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Re: 85' Spree fires up then dies

Post by Rideslikenacho »

Check to make sure you are getting consistent fuel. Petcock is vacuum operated meaning if you lose vacuum or the petcock is broke you won’t get fuel. Could also have a clogged fuel line. I’d be inclined to start there. Remove the vacuum and gas line from carb body and put negative pressure on the vacuum line and see if fuel flows out the fuel line. Sounds a lot like a clogged pilot jet too.
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Re: 85' Spree fires up then dies

Post by Therider94 »

Rideslikenacho wrote: Tue Nov 02, 2021 9:50 am Check to make sure you are getting consistent fuel. Petcock is vacuum operated meaning if you lose vacuum or the petcock is broke you won’t get fuel. Could also have a clogged fuel line. I’d be inclined to start there. Remove the vacuum and gas line from carb body and put negative pressure on the vacuum line and see if fuel flows out the fuel line. Sounds a lot like a clogged pilot jet too.
I am getting consistent fuel. I replaced both the fuel line and the vacuum line and have tested both. I have cleaned the carb twice now and am sure that the jets are not clogged.
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Re: 85' Spree fires up then dies

Post by Rideslikenacho »

Therider94 wrote: Tue Nov 02, 2021 10:11 am
Rideslikenacho wrote: Tue Nov 02, 2021 9:50 am Check to make sure you are getting consistent fuel. Petcock is vacuum operated meaning if you lose vacuum or the petcock is broke you won’t get fuel. Could also have a clogged fuel line. I’d be inclined to start there. Remove the vacuum and gas line from carb body and put negative pressure on the vacuum line and see if fuel flows out the fuel line. Sounds a lot like a clogged pilot jet too.
I am getting consistent fuel. I replaced both the fuel line and the vacuum line and have tested both. I have cleaned the carb twice now and am sure that the jets are not clogged.
If the carb’s definitely clean, it could be a faulty auto bystarter. They can fail open or closed allowing more or less fuel into the carb. I had a elite that did exact same thing, would fire up, use up the gas in the bowl then croak. Replaced the bystarter and fixed the issue.
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Re: 85' Spree fires up then dies

Post by Therider94 »

Rideslikenacho wrote: Wed Nov 03, 2021 7:07 am
Therider94 wrote: Tue Nov 02, 2021 10:11 am
Rideslikenacho wrote: Tue Nov 02, 2021 9:50 am Check to make sure you are getting consistent fuel. Petcock is vacuum operated meaning if you lose vacuum or the petcock is broke you won’t get fuel. Could also have a clogged fuel line. I’d be inclined to start there. Remove the vacuum and gas line from carb body and put negative pressure on the vacuum line and see if fuel flows out the fuel line. Sounds a lot like a clogged pilot jet too.
I am getting consistent fuel. I replaced both the fuel line and the vacuum line and have tested both. I have cleaned the carb twice now and am sure that the jets are not clogged.
If the carb’s definitely clean, it could be a faulty auto bystarter. They can fail open or closed allowing more or less fuel into the carb. I had a elite that did exact same thing, would fire up, use up the gas in the bowl then croak. Replaced the bystarter and fixed the issue.

OK, I will try replacing the bystarter. I'm not sure what else it could be.
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Re: 85' Spree fires up then dies

Post by Therider94 »

One thing is that the airbox is not connected as the connector tube is bad and the lid is missing. Could this be the culprit?
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Re: 85' Spree fires up then dies

Post by Volvo850R »

In my experience I always drill a hole in the gas cap to help the air vent on this old scoots. Just don’t fill up to the top and wheelie around.
1984 elite ch125
1985 spree nq50
1986 spree nq50
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Re: 85' Spree fires up then dies

Post by Wheelman-111 »

Greetings:

Quoth TheRider94:
One thing is that the airbox is not connected as the connector tube is bad and the lid is missing. Could this be the culprit?
Umm, yes, very likely. It'll run as long as the bystarter richens the mixture, but as it closes, there's not enough vacuum in the intake circuit to suck fuel down from the stingy Idle circuit. Put everything back to stock if you can, including the intake tube and airbox lid.
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Re: 85' Spree fires up then dies

Post by Therider94 »

Wheelman-111 wrote: Thu Nov 04, 2021 11:12 pm Greetings:

Quoth TheRider94:
One thing is that the airbox is not connected as the connector tube is bad and the lid is missing. Could this be the culprit?
Umm, yes, very likely. It'll run as long as the bystarter richens the mixture, but as it closes, there's not enough vacuum in the intake circuit to suck fuel down from the stingy Idle circuit. Put everything back to stock if you can, including the intake tube and airbox lid.
OK, yeah I have a new bystarter on the way so hopefully that actually keeps it running for longer than a couple seconds. I would love to put the airbox back to stock but I can't find the pieces I need for the life of me.
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Re: 85' Spree fires up then dies

Post by Wheelman-111 »

Greetings:

Your bystarter is probably fine. I have seen the following misunderstanding numerous times:
The Default position for the bystarter is "On", and an enriched mixture + a little extra air happens at startup. This is true even with a "failed" bystarter! If the carb is allowed to run dry, especially in hot storage for one or more years, the bystarter slider becomes Cemented to the housing in the "full choke" or rich position. The scooter, assuming all else is in order, will start, and run for 3-5 minutes until the bystarter slowly closes off the rich mixture. If the idle circuit isn't clogged, the scooter should idle at 1800. If the Idle circuit IS clogged, the scooter will stall. So I think your bystarter is actually OK.
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Re: 85' Spree fires up then dies

Post by Therider94 »

Wheelman-111 wrote: Fri Nov 05, 2021 9:24 pm Greetings:

Your bystarter is probably fine. I have seen the following misunderstanding numerous times:
The Default position for the bystarter is "On", and an enriched mixture + a little extra air happens at startup. This is true even with a "failed" bystarter! If the carb is allowed to run dry, especially in hot storage for one or more years, the bystarter slider becomes Cemented to the housing in the "full choke" or rich position. The scooter, assuming all else is in order, will start, and run for 3-5 minutes until the bystarter slowly closes off the rich mixture. If the idle circuit isn't clogged, the scooter should idle at 1800. If the Idle circuit IS clogged, the scooter will stall. So I think your bystarter is actually OK.
OK. So if the bystarter isn't the culprit, then it must be not having the airbox hooked up? I can't think of anything else that it would be.
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Re: 85' Spree fires up then dies

Post by Wheelman-111 »

Greetings:

Rides like Nacho said bystarters can fail open or closed. Any thoughts? I have not heard of this. If the scooter runs frequently the fuel in the circuit will be liquid, and the slide will retract as soon as the element cools. Only gums up - in the "OPEN" position, after years of neglect. In my opinion... I just don't see how the bystarter can fail in the Closed position.

An intact and airtight Airbox creates negative pressure -relative vacuum or "suction" - in the intake tract and carb throat. This suction pulls fuel up through the teeny-tiny Idle circuit of that PA carb. In the absence of that vacuum, the carb can't cough up enough fuel to sustain combustion, except while the bystarter is adding fuel and air.
PLUS: that idle circuit is so small that it Gums Up very easily and more than a few of us have had to repeat the carb cleaning process multiple times before success. Since the Stock parts you need have become scarce, you may be limited in options. You could test with a small funnel fitted to the bellmouth of the carb and experiment with apertures cut down from a pencil-sized opening to larger.

A Forum member sells (or sold?) a kit to convert the intake manifold to run flatslide carbs from Polini et. al. Once installed everything becomes adjustable - different pilot and main jets are still available. However it is a path to the Dark Side. Next thing you'll want is a bore kit, gears...
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
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Re: 85' Spree fires up then dies

Post by Rideslikenacho »

Wheelman-111 wrote: Thu Nov 04, 2021 11:12 pm Greetings:

Quoth TheRider94:
One thing is that the airbox is not connected as the connector tube is bad and the lid is missing. Could this be the culprit?
Umm, yes, very likely. It'll run as long as the bystarter richens the mixture, but as it closes, there's not enough vacuum in the intake circuit to suck fuel down from the stingy Idle circuit. Put everything back to stock if you can, including the intake tube and airbox lid.
Yep, had similar issues on this Spree I have. If the airbox lid is not completely sealed it won’t create enough negative pressure to pull a syphon and open the petcock diaphragm to allow enough fuel to the carb. Hold your hand completely over the carb airbox side and crank over to see if it will fire up that way.

@wheelman - I’ve had one fail open and another was stuck inside the carb body from lack of use. Given the internal mechanics, if it failed I can see your logic in that the needle would recede as soon as the internal wax cooled. If it failed prior, the needle would never have fully extended. Either scenario the needle would be in the open or enrichment stage. Left for extended periods of time, that enrichment orifice on the side of the float bowl the needle resides in will eventually clog causing the lack of fuel condition where the solution would be carb cleaning but also the point of original failure was the faulty bystarter.
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Re: 85' Spree fires up then dies

Post by Therider94 »

FIXED! I picked up an airbox lid from a fellow member, got everything put back to stock. Boom! starts right up.
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Re: 85' Spree fires up then dies

Post by Rideslikenacho »

Therider94 wrote: Thu Nov 18, 2021 3:02 pm FIXED! I picked up an airbox lid from a fellow member, got everything put back to stock. Boom! starts right up.
Nice! Was curious about this since mine seems to have similar issue near the airbox. I’m going to replace the oring gasket on mine and ordered material off amazon recently.
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