I'm running a Prox 440F and will be getting a Holzman Tempafloe to keep the jetting spot on but I just found this product called the YOST Performance Tube that is suppose to maximize your fuel atomization. They have a decent reputation with the Harley Davidson crowd and I'm just wondering if anyone has used them on a sled yet? Might be a nice 1-2 punch with the Tempafloe and the YOST.

Thoughts?

Could you direct us to the YOST Performance Tube site??

Auggie

Here ya go.

http://www.yostperformance.com/

one of my first add-ons for the harley.and yes I have installed many for guys with great results.but harleys are really bad about letting fuel puddle in the intake so they really need help.if you do try one let us know what you think.

Thanks.

Auggie

So what is a Yost Performance Tube, exactly? The web site does tell, or show what it is, it just tells you what it does, or is supposed to do. I'll go out on a limb and assume there is a tube involved, but where does it go and what is the priciple of operation? ???

read this

There are several benefits when you use the Yost Power Tube.

1. Produces a very fine mist
The Yost Power Tubes by design, produce a very fine mist, finer than most production fuel injection systems and can be seen and observed by removing the air cleaner and looking into the carburetor venturi.

(BE CAREFUL, WE DON'T WANT YOU TO BURN YOUR EYES, NOSE, OR ANYTHING ELSE.) This very fine mist allows the fuel to stay in suspension longer for better control of air and fuel mixtures and can be almost perfectly matched for almost any throttle position.

2. Mid-Range Power and Horsepower
One of the Yost Power Tubes greatest benefits is extremely good PART THROTTLE response and MID-RANGE performance. This is the most affordable horsepower gain that money can buy. Typically, there will be an increase of 2-5 horses.

3. Increased Combustion Efficiency
The Yost Power Tube provides increased combustion efficiency for a more complete burning of the fuel mixture so that you need less fuel to do the same job. The Yost Power Tube is specifically designed to synchronize the engine demand with the air and fuel requirements. (In other words, this Yost Power Tube gives you the proper amount of fuel at just the right time.)

4. Smoother Running Engine
You will have a smoother running engine through the entire range, due in large part to the increased combustion efficiency. There is a greatly reduced possibility of pockets of raw fuel burning randomly.

5. Detonation
In your combustion chambers, and again because of greater combustion efficiency, the possibility of detonation is also reduced. We have never ridden in scientifically or atmospherically ideal conditions, so I would still be somewhat conservative with compression ratios and ignition timing.

6. Reduced Possibility of Part Throttle Lean Spot
This means that ideally you can use a larger carburetor, bigger ports, and more aggressive camshafts with a reduce possibility of a part throttle lean condition. (smaller fuel particles are easier to move and lift than larger particles) but use some wisdom and remember that if you set up a street engine to DRAG specifications, you may have drivability problems at lower engine speeds.

7. Shorter Warm-up & Reduced Spark plug Fouling
Most riders also experience shorter warm-up times and a reduced possibility of spark plug fouling. With increased efficiency, the additives present in gasoline are more completely burned, so much so that it is difficult to leave residue deposit on the spark plugs.

8. Jetting For Atmospheric Conditions
Providing that your jetting is fairly close to the atmospheric conditions that you are riding in, your engine will run cooler. This can be checked with a thermometer in your oil bag.

9. Surges & Flat Spots
The Yost Power Tube is designed to almost completely eliminate surges and flat spots by controlling air-fuel mixtures more precisely, and provides an almost unbelievably smooth throttle response and carburetor circuit transition.

10. Easier To Start The Main Fuel Circuit
With the Yost Power Tube installed, it is much easier to start the main fuel circuit, while needing less manifold vacuum to do so.

I will post a pic later if no one beats me too it.

How much do they cost?

Around $150 for a twin. They are going to be a vendor at the Outlaw grass drags in Princeton, MN. Hopefully they will have some good event pricing. I'm looking to get a set.

yost power tube for the s&s carb

Where would the tube install in our carbs?

needle jet ??? ,but I have not seen one to say for sure

Is this not the same principle as a dial-a-jet system? It also delivers emulsified fuel + has similiar operating caracteristics.

Originally posted by dooman@Aug 12 2003, 10:30 PM
needle jet ??? ,but I have not seen one to say for sure
That's what I was afraid of. What happens on these TM-40 flatslides with the fixed needle jet? Anyone know?

Does it install into the bellmouth like the Dial-a-Jet system, or does it go on top of the needle jet, with the jet needle passing through it, in the centre of the venturi? ???

I have e-mailed Yost to see if we can get an answer from them. I'll let you know as soon as I hear anything from them.