CR 500 Power Jet Induction

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CR 500 Power Jet Induction

* With any internal combustion motor, volumetric efficiency is the key to making power - that is how much air the motor really pumps (Dirt Bike Magazine 2012).

Power Jet Induction --- Many engine builders do exceptional work. I admire what they do. They make power by increasing or modifying how air-fuel flows through the motor, when the valves are open. Power Jet Induction ( Path of Least Resistance Continuous Flow Induction ) makes more power by utilizing the full force of intake energy, even when the valves are closed! Combining Continuous Flow Induction with pressure activated reed valves creates an exceptional variable valve timing system. It makes amazing torque and power. The more your motor revs, the more it pumps and the more it pumps the better your motor runs. It's the same energy that drives your impact wrench!

Jet Tech --- To be the ultimate machine, a 2-stroke needs strong 4-stroke like torque combined with it’s awesome top-end power. The problem is pulsating back-pressure (sequenced to closing reed valves) stifles it. Although pulsating closed reed valve reaction is most noticeable at slow speeds (ring a ding, ding), it stifles power everywhere. Continuous Flow Induction captures pulsating back-pressure in the Pulse Chamber, then Jets it through a Sonic Tube back into the throat of your carburetor as the reeds open. This sequenced intake timing works just like the pulsating in your expansion chamber (only on the intake side) to fill the cylinder each and every stroke with more air-fuel. It’s not hard to imagine, that the double benefit of utilizing back-pressure and maintaining continuous high velocity intake flow to Pump Up the power is better, than allowing intake flow to recoil backwards every time the reeds close! It’s also why your carburetor works amazingly well with Continuous Flow Induction. It even sounds better --- Vrrooom! By the way, CFI works excellent on 4-strokes, but there is no way they can run with a Pumped Up 2-stroke.
You'll love your Pumped Up 2-stroke.

I would like to thank the many loyal customers for their business and support. They make this project fun and successful.

Ron, Pulse Engineering 406-248-5595 Patents 4848281 & 6167857 others pending

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[Sandblaster]

Here is by far the best explanation I have heard as to how Pulse Induction works and why it works.

Pulse Induction, an explanation.
By Adam Miller.
Most guys are under the mis conception that everything is inward like the red lines in this drawing show.

PULSE INDUCTION 1.png (83.03 KiB) Viewed 8258 times

In reality the crankcase pressure closing the reeds makes a reversion wave that travels back towards the air filter picking up fuel for a second time as it passes the metering system and almost completely stalling the inward flow. Blue lines represent the reversion.

PULSE INDUCTION 2.png (91.24 KiB) Viewed 8258 times

Now we understand that the actual inbound mixture has a triple metered wave and a single metered wave drawn into the engine. As the wave is drawing fuel on its reversion pass it is also back feeding the fuel circuit and forcing the fuel from the carburetor metering back to the bowl which causes the first 10-20% of the inward bound charge to draw a leaner mixture until the fuel returns.
The strength of the reversion wave is altered not by the crankcase compression of the motor, but by the crankcase volume. It's this reason that a 125cc motor takes a 192 main jet, a 250 is 180, and the 500's a 172 (average jet requirement). Lesser pulse wave strength on smaller motors means less multiplied fuel so an initial larger jet is needed. This lower strength wave makes a pulse unit less effective on small cc motors. It is not uncommon to see the surge of the stock reed boot on a CR500, the appearance of the boot absorbing this pressure does not have any measure able difference when compared to the wave in a rigid inlet like the Boyesen Rad Valve .

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A Pulse Induction system replaces the stock boot that mates the reed to carb, its cone shaped chamber traps the majority of the reversion wave (blue) and channels it into the pulse tube where a specific length tube dictates the time for it to be re-introduced as an inbound charge. Metering of the fuel has now been almost perfectly restricted to a single pass of the metering system which no longer is having fuel forced out of it. The single metering pass has now given us an acurate and predictable means of metering the fuel. Commonly the jet sizes need to be increased since they are no longer working on multiplied passes. Throttle response is crisp since you are no longer stalling the inlet stream 1/2 the time
Here you can see the reversion waves time has it half ways back to the plenum while the reeds are still closed.

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Timing of the pulse wave set by the length of the tube introduces the wave to the chamber as the reed opens, adding velocity to push the almost stalled inlet stream (red). With the inertia wave more air is introduced than the motor can otherwise draw on its own because it is starting at a velocity equal to what is created 1/3-1/2 of the time into the standard intakes draw, basically its "supercharged". The Pulse system works from idle to high rpm and close to wide open throttle positions since its re-introduction point is post throttle valve. Commonly the engines will not draw fuel consistantly through the rpm range because of the reversion strength, The pulse equipped motors will continue to draw consistantly and evenly to extended rpm ranges not accessable without pulse induction. Intake tempatures are reduced since additional single metered air is aquired and engine tempatures are reduced significantly to where it is reccomended to run a heat range hotter spark plug than normally used.

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I've done my best to explain this, I expect questions and have no problem answering them.
Adam Millar

[Sandblaster]

Here is a setup that a member is using on his KX250 1998 or 1999 as he is using the 1851 cylinder..

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[Jchristopher]

Is anyone able to compare the advantages of the increased airflow this provides when the reeds open to the advantages the Dick's intellijet/taper bore/x wing would provide? It looks like this is more of a throttle response and torque increase where the Dick's intellijet and taper bore look to mostly improve top end with an increased amount of fuel being sprayed to combust when the RPM's are higher. With the X wing separating the turbulent air and organizing the airflow into the reed cage, it looks like their way of addressing the issue of reversion. I contacted Ron with Pulse Engineering and he told me that his air induction system won't work with the Dick's racing intellijet and taper bore (excluding the x wing). This leads me to ask which should be more beneficial?

On a side note, I don't fully understand why they won't work together as I would think that they would almost compliment each other since you'd be receiving increased fuel WITH increased air rather than one or the other.

[Jchristopher]

Disregard that the complimentary statement as I remembered that the intellijet kicks in at higher RPM's while the air induction is upon reed valve opening. But I still don't understand why they wouldn't work together unless the jetting would just be impossible.