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I m running 60mm Flowed Crank and 210 Mhr and full other stuff. I am planning to increase my Carb 30 mm to 35mm and time to add Fuel Pump but ı have no idea about Lt/h?
DELL`ORTO 55lt/h ıs ıt okey?
DELL`ORTO 55lt/h ıs ıt okey?
Or MIKUNI 20 liters/h?
Or MIKUNI 20 liters/h?
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14ltr mikuni
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Return line
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I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
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I am thinking on putting a pump too, cause I am experiencing starvation when in reserve and a bit lower. I was thinking to use the new plastic Mikuni pump that Piaggio uses on all newer models. I have seen it on the 50cc Runner RST, being used directly from the tank to the carb, so I am assuming there's no flooding issues. The only question I have is to where I put the vacuum tube. On the Runner the vacuum is between the reed valve and crank. First of all, I don't want to drill my cases. Will it work directly on the carb or the manifold?? I am still using the "disc valve" system. Any experiences??
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Why not tap in a hose barb into your inlet manifold?
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I feed the carb from a tee at the top of the return line. that way:
1. you get gravity feed with a constant height from about the top of the tank
2. if you leave the fuel on it will only drain what's in the line, no risk of dumping the whole tank or flooding.

on the down side it takes 5 kicks or so to prime it if it's not run in a while.
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SaFiS wrote:
I am thinking on putting a pump too, cause I am experiencing starvation when in reserve and a bit lower. I was thinking to use the new plastic Mikuni pump that Piaggio uses on all newer models. I have seen it on the 50cc Runner RST, being used directly from the tank to the carb, so I am assuming there's no flooding issues. The only question I have is to where I put the vacuum tube. On the Runner the vacuum is between the reed valve and crank. First of all, I don't want to drill my cases. Will it work directly on the carb or the manifold?? I am still using the "disc valve" system. Any experiences??
It is well documented the large frames run weak at less than half tank
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I'm using a Gilera runner fuel pump. No issues & easy to come by
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I'm running an electric fuel pump on my '80 P200 w/Polini 208 and Polini 28mm PWK. It's been a great setup and runs strong even to the point of the tank being almost completely empty.

It's a Facet Posi Flo 60304 made for carbed ATV's. It only pushes 2 psi max so it doesn't overpower the PWK's float.

It's wired via a relay and switch and I have a digital voltmeter to keep an eye on the (very small) 4ah battery. I was originally worried that the charging system wouldn't keep up with the fuel pump's draw but I've been running this setup for six months + now and many many miles and I've never needed to charge the battery. The voltmeter reads 14+ volts at mid to high RPM's and the system has been rock solid.

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Resurrecting an old thread, anybody try one of these?
niz76 wrote:
I'm running an electric fuel pump on my '80 P200 w/Polini 208 and Polini 28mm PWK. It's been a great setup and runs strong even to the point of the tank being almost completely empty.

It's a Facet Posi Flo 60304 made for carbed ATV's. It only pushes 2 psi max so it doesn't overpower the PWK's float.

It's wired via a relay and switch and I have a digital voltmeter to keep an eye on the (very small) 4ah battery. I was originally worried that the charging system wouldn't keep up with the fuel pump's draw but I've been running this setup for six months + now and many many miles and I've never needed to charge the battery. The voltmeter reads 14+ volts at mid to high RPM's and the system has been rock solid.

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This thread kind've died off, but I installed a self-regulating Dellorto fuel pump on my FrankenSprint a few months ago now with no external regulator or return flow valve or anything and it's been rock solid. This is a motor that's currently putting out about 22 HP with a 34mm PWK, and it's fine from idle straight through to WOT.

If you haven't committed to anything yet, I strongly recommend it.
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chandlerman wrote:
This thread kind've died off, but I installed a self-regulating Dellorto fuel pump on my FrankenSprint a few months ago now with no external regulator or return flow valve or anything and it's been rock solid. This is a motor that's currently putting out about 22 HP with a 34mm PWK, and it's fine from idle straight through to WOT.

If you haven't committed to anything yet, I strongly recommend it.
That's great! Doesn't appear to be widely available but still. Certainly beats the pita that is setting up a bypass.
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Ginch wrote:
chandlerman wrote:
This thread kind've died off, but I installed a self-regulating Dellorto fuel pump on my FrankenSprint a few months ago now with no external regulator or return flow valve or anything and it's been rock solid. This is a motor that's currently putting out about 22 HP with a 34mm PWK, and it's fine from idle straight through to WOT.

If you haven't committed to anything yet, I strongly recommend it.
That's great! Doesn't appear to be widely available but still. Certainly beats the pita that is setting up a bypass.
You're telling the guy who lived with the PITA that was fitting an automotive low pressure regulator into his fuel system to avoid setting up a bypass

I was a little specious when I first ordered it, but am now completely sold on it.
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Yes... that did seem like a special level of commitment!
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chandlerman wrote:
This thread kind've died off, but I installed a self-regulating Dellorto fuel pump on my FrankenSprint a few months ago now with no external regulator or return flow valve or anything and it's been rock solid. This is a motor that's currently putting out about 22 HP with a 34mm PWK, and it's fine from idle straight through to WOT.

If you haven't committed to anything yet, I strongly recommend it.
That looks interesting, they also appear to have a bypass. https://www.accelerationkarting.com/RighettiFuelReservoir
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Christopher_55934 wrote:
That looks interesting, they also appear to have a bypass. https://www.accelerationkarting.com/RighettiFuelReservoir
Yeah, but for the price of the bypass, you're halfway to the price of the pump, and if you're building motors that need a fuel pump, you should be able to afford the extra $25 for the ideal solution.
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chandlerman wrote:
Christopher_55934 wrote:
That looks interesting, they also appear to have a bypass. https://www.accelerationkarting.com/RighettiFuelReservoir
Yeah, but for the price of the bypass, you're halfway to the price of the pump, and if you're building motors that need a fuel pump, you should be able to afford the extra $25 for the ideal solution.
I was thinking more for people putting in an electric fuel pump. I was thinking so I wouldn't have to try and drill my casing on a assembled motor.
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Just drill the cases and be done. You can tap it for the nipple and close it off with a bolt if you ever want to go back.

After all, there's no such thing as a Concourse Restoration Stella
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chandlerman wrote:
Just drill the cases and be done. You can tap it for the nipple and close it off with a bolt if you ever want to go back.

After all, there's no such thing as a Concourse Restoration Stella
Not cracking the P200 cases to drill them, it was a fresh build. That little container looks like a bottle with a over flow. Pump keeps it full and returns extra to tank. I just can't bring myself to dead head a pump, with no flow when the float is closed. I was thinking a fuel filter with two outlets could be used. Route one to carb, a second to tank. Should act as a small reservoir to feed float bowl full.
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Oh, yeah! I forgot you got the P200 motor for it.

I'd probably do it anyway, just vacuum as I drilled, plus pull the cylinder to get something in there to catch what got through, but I also realize not everyone is as gonzo as I am about this stuff .
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Christopher, is your pump going to run the whole time? And where/how are you going to add a return feed to the tank?
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Ginch wrote:
Christopher, is your pump going to run the whole time? And where/how are you going to add a return feed to the tank?
I don't have any answers just thoughts at the moment, exploring options. An electric pump doesn't require drilling the case and could be mounted under the tank in the cavity easy enough. A person really just needs a small tank with an overflow, for the pump to feed. Keep the tank full and the extra goes back to the main tank. When you stop an electric pump or cause rotor lock it draws maximum current, not a good thing.
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Christopher_55934 wrote:
Ginch wrote:
Christopher, is your pump going to run the whole time? And where/how are you going to add a return feed to the tank?
I don't have any answers just thoughts at the moment, exploring options. An electric pump doesn't require drilling the case and could be mounted under the tank in the cavity easy enough. A person really just needs a small tank with an overflow, for the pump to feed. Keep the tank full and the extra goes back to the main tank. When you stop an electric pump or cause rotor lock it draws maximum current, not a good thing.
Is there a pressure switch available for electric fuel pumps? Would be nice to simply only turn it on when your secondary reservoir is low. A while ago I was thinking that the float bowl from an SU carb could be utilised as a reservoir. They have a decent float needle, can be bought as a separate item from the carb itself, and have a mounting point that could be utilised in a custom situation.
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You could certainly get a float switch that would cause the pump to activate only when the bowl was low. If the pump was noticeable at all while riding, though, I think the constant on-off clicking would drive you nuts after about five miles, though.

Of course, I say this from a position of complete ignorance, never having run an electric fuel pump myself
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chandlerman wrote:
... the constant on-off clicking would drive you nuts...
You mean over the BRRAAAP noise?

Razz emoticon
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LOL!

I knew I was going to get some crap for that and I know it sounds dumb, but Solenoids have a funny way of making themselves heard and felt, even when you wouldn't think it's possible.
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My first car was a 1953 Morris Minor. It had an SU fuel pump with points. I always found the noise it made comforting... because when you couldn't hear it any more, you coasted to the side of the road, got out the hammer, slid under the back of the car and gave it a light tap. Then off you'd go. Until next time!
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Hah!

My dad had an Austin-Healy in the early 60's when he was in the navy. The exhaust would constantly vibrate loose, so he'd take it onto the docks and get one of the machinist mates to weld it back on about every two weeks.

They don't make cars like that any more...for good reason.
⬆️    About 6 months elapsed    ⬇️
@108 avatar
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Ginch wrote:
I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
I've seen all the pictures and diagrams... but I'm a little confused... why would the restrictor help with flooding? Wouldn't the bypass just control the fuel needed at high vacuum? Shouldn't the restrictor go between the carb and the pump if it's needed?

At high vacuum, wouldn't you want the fuel directed away from the carb to make sure it's not getting too much?

Just trying to get my head around it...
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108 wrote:
Ginch wrote:
I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
I've seen all the pictures and diagrams... but I'm a little confused... why would the restrictor help with flooding? Wouldn't the bypass just control the fuel needed at high vacuum? Shouldn't the restrictor go between the carb and the pump if it's needed?

At high vacuum, wouldn't you want the fuel directed away from the carb to make sure it's not getting too much?

Just trying to get my head around it...
The float along with the needle and seat setup, on a gravity fed carburetor aren't made to handle the pressure of a fuel pump. The bypass acts as a crude regulator or bypass for extra pressure and fuel flow. Once you dead head a pump by turning off the flow or closing the input with a float, it will build maximum pressure even with a small hole from a restriction. The pressure will force fuel passed the needle and over fill the float bowl.

My TMX30 carburetor has a separate needle and seat setup for gravity fed vs pump fed operation or pressure.
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Christopher_55934 wrote:
108 wrote:
Ginch wrote:
I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
I've seen all the pictures and diagrams... but I'm a little confused... why would the restrictor help with flooding? Wouldn't the bypass just control the fuel needed at high vacuum? Shouldn't the restrictor go between the carb and the pump if it's needed?

At high vacuum, wouldn't you want the fuel directed away from the carb to make sure it's not getting too much?

Just trying to get my head around it...
The float along with the needle and seat setup, on a gravity fed carburetor aren't made to handle the pressure of a fuel pump. The bypass acts as a crude regulator or bypass for extra pressure and fuel flow. Once you dead head a pump by turning off the flow or closing the input with a float, it will build maximum pressure even with a small hole from a restriction. The pressure will force fuel passed the needle and over fill the float bowl.

My TMX30 carburetor has a separate needle and seat setup for gravity fed vs pump fed operation or pressure.
Sorry buddy, you lost me at dead head...

I get that the float needle isn't suppose to take the pressures of a pump...

But wouldn't all the pressures head to the needle regardless? And having a hose without the restrictor would make sense no? Maybe I'm being dense here...

But didn't know the tmx had that... that's a pretty cool feature...
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108 wrote:
Christopher_55934 wrote:
108 wrote:
Ginch wrote:
I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
I've seen all the pictures and diagrams... but I'm a little confused... why would the restrictor help with flooding? Wouldn't the bypass just control the fuel needed at high vacuum? Shouldn't the restrictor go between the carb and the pump if it's needed?

At high vacuum, wouldn't you want the fuel directed away from the carb to make sure it's not getting too much?

Just trying to get my head around it...
The float along with the needle and seat setup, on a gravity fed carburetor aren't made to handle the pressure of a fuel pump. The bypass acts as a crude regulator or bypass for extra pressure and fuel flow. Once you dead head a pump by turning off the flow or closing the input with a float, it will build maximum pressure even with a small hole from a restriction. The pressure will force fuel passed the needle and over fill the float bowl.

My TMX30 carburetor has a separate needle and seat setup for gravity fed vs pump fed operation or pressure.
Sorry buddy, you lost me at dead head... (That is completely stopping the flow from a pump)

I get that the float needle isn't suppose to take the pressures of a pump...

But wouldn't all the pressures head to the needle regardless? And having a hose without the restrictor would make sense no? Maybe I'm being dense here...

(Not sure if this will help or not haven't had a cup of coffee yet this morning.

If you have a garden hose with good pressure and try stopping the flow with your thumb you can't, water will get passed your thumb and leak out that is what happens with a needle and seat in your carburetor connected directly to most fuel pumps and causes flooding.

Now, you add a "Y" to the hose to allow some water to flow one direction and some to flow the other, the side of the "Y" that connects to the carburetor has more restriction than the other hose on the "Y" with no restriction. Now most of the fuel is going out of the hose with no restriction, or bypass and you aren't getting enough fuel to the carburetor. So you add a restriction to the hose not connected to the carburetor so some pressure still builds up and you get pressure in both directions.

The fuel injection system in my older sports car 2007, doesn't have a variable speed fuel pump, the fuel pump is always running at the same speed. It has a pressure regulator on the return side and bleeds off excess pressure and fuel to the gas tank to maintain 68 psi of pressure on the rail that houses the fuel injectors. This is what people are trying to accomplish with the fuel pump at a much lower pressure.


My 2015 car has fuel injection with a variable speed fuel pump, it monitors the pressure at the fuel rail that holds the fuel injectors, the pump speed is varied to regulate fuel pressure and has no return line. This results in less pump wear and no need for a return line.


But didn't know the tmx had that... that's a pretty cool feature...
@108 avatar
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@108 avatar
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Christopher_55934 wrote:
108 wrote:
Christopher_55934 wrote:
108 wrote:
Ginch wrote:
I use one like Ssteam177. I don't have a return line, I have a link/bypass between the in and out with a restrictor in the line. The restrictor I'm using is the little screw-on bit on the end of a spark plug... any smaller and it seems to flood too easily.
All of these pumps supply more than you need, which is why you have to deal with excess fuel with a return or bypass.
I've seen all the pictures and diagrams... but I'm a little confused... why would the restrictor help with flooding? Wouldn't the bypass just control the fuel needed at high vacuum? Shouldn't the restrictor go between the carb and the pump if it's needed?

At high vacuum, wouldn't you want the fuel directed away from the carb to make sure it's not getting too much?

Just trying to get my head around it...
The float along with the needle and seat setup, on a gravity fed carburetor aren't made to handle the pressure of a fuel pump. The bypass acts as a crude regulator or bypass for extra pressure and fuel flow. Once you dead head a pump by turning off the flow or closing the input with a float, it will build maximum pressure even with a small hole from a restriction. The pressure will force fuel passed the needle and over fill the float bowl.

My TMX30 carburetor has a separate needle and seat setup for gravity fed vs pump fed operation or pressure.
Sorry buddy, you lost me at dead head... (That is completely stopping the flow from a pump)

I get that the float needle isn't suppose to take the pressures of a pump...

But wouldn't all the pressures head to the needle regardless? And having a hose without the restrictor would make sense no? Maybe I'm being dense here...

(Not sure if this will help or not haven't had a cup of coffee yet this morning.

If you have a garden hose with good pressure and try stopping the flow with your thumb you can't, water will get passed your thumb and leak out that is what happens with a needle and seat in your carburetor connected directly to most fuel pumps and causes flooding.

Now, you add a "Y" to the hose to allow some water to flow one direction and some to flow the other, the side of the "Y" that connects to the carburetor has more restriction than the other hose on the "Y" with no restriction. Now most of the fuel is going out of the hose with no restriction, or bypass and you aren't getting enough fuel to the carburetor. So you add a restriction to the hose not connected to the carburetor so some pressure still builds up and you get pressure in both directions.

The fuel injection system in my older sports car 2007, doesn't have a variable speed fuel pump, the fuel pump is always running at the same speed. It has a pressure regulator on the return side and bleeds off excess pressure and fuel to the gas tank to maintain 68 psi of pressure on the rail that houses the fuel injectors. This is what people are trying to accomplish with the fuel pump at a much lower pressure.


My 2015 car has fuel injection with a variable speed fuel pump, it monitors the pressure at the fuel rail that holds the fuel injectors, the pump speed is varied to regulate fuel pressure and has no return line. This results in less pump wear and no need for a return line.


But didn't know the tmx had that... that's a pretty cool feature...
Got you... I understand the path of least resistance theory... but wouldn't a bypass be enough to levitate the pressure but enough fuel will still go to the carb side because fluid will still flow?

So the restrictor in the bypass side needs to be similar size to the carb float needle hole... if not all the pressure will go to the carb...?
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@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
108, not exactly sure of the physics involved but in reality the bypass lowers the pressure. Prior to the fitting of the restrictor, after a bit of a longer run at mid to higher speeds, you'd pull up to a stop and the thing would flood every time. Ideally you want the pressure to be just a little above what you'd get with a full tank... and continue to get that pressure down to empty.
@108 avatar
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UTC quote
Ginch wrote:
108, not exactly sure of the physics involved but in reality the bypass lowers the pressure. Prior to the fitting of the restrictor, after a bit of a longer run at mid to higher speeds, you'd pull up to a stop and the thing would flood every time. Ideally you want the pressure to be just a little above what you'd get with a full tank... and continue to get that pressure down to empty.
Yeah, i got flooding before without a restrictor... wasnt too much, but it came out of the overflow tube...

But now it seems to have spooge coming out of the exhaust... not sure if theres too much pressure still going to the carb...

I'll try adding the spark plug end restrictor on the bypass side and see if it evens out the pressure... I would have thought it would make the pressure higher in the carb, but seems like I'd be wrong...
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