Power Now

8 replies to this topic
  • Wayne_Dowsing

Posted February 23, 2005 - 06:46 PM


What is a "Power Now" and how does it improve performance?

Sort of looks like a reed valve for a 4 stroke



Posted February 23, 2005 - 09:00 PM


A PowerNow gives you better throttle response and a little more bottom-end power.

It takes some away from the top-end though. It all depends on how your riding if you need one.


  • elburro

Posted February 23, 2005 - 09:26 PM


It seems like it made my bike easier to start too.

  • grayracer513

Posted February 23, 2005 - 10:50 PM


Makes the throttle more repsonsive up to about half throttle. I use one on 250F, but I wouldn't bother on the 450. We suffered no loss of top end at all.

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  • Crabtree426

Posted February 24, 2005 - 07:58 PM


If you ride tight trails, but it. It helps throttle response and gives a boost on the low end. I have one and think it's worth the $$$$.

  • SXP

Posted February 24, 2005 - 10:26 PM


Anyone remember the website address of another company that sells a similar gizmo but for about 1/3 the price? I remember seeing it posted here about 8 months ago, but can't find it anymore. Thanks.

  • yz_for_me

Posted February 25, 2005 - 07:50 AM


The theory behind the Power Now as I understand it.

Here's the "problem" with a normal carb. Think about the stream of air flowing through your intake at say half throttle. When the air reaches the carb, the upper half of that air stream hits the carburator slide and is forced down into the air traveling at the lower half of the stream creating turbulance. This turbulant air entering the carburator causes a decrease in performance in carb performance.

What the Power Now is supposed to do is divide the intake into two channels: An upper half and a lower half. At lower throttle positions (where the carb slide is only partially open) the air in the airbox is drawn into the lower channel. Since the upper channel is blocked by the carb slide, there is virtually no air going through the upper channel where it could hit the carb slide. With no air being diverted down into the lower half of the intake, this eliminates the turbulace problem as explained above.

Hope this makes sense.

If you want a cheaper way to find out if it works do a search on "James Now". It's basically a homemade Power Now.

  • RippinInColorado

Posted February 25, 2005 - 08:59 AM


YZ4ME is correct - cuts the size of the carb in half when at half throttle or less. This improves responsiveness when you open the throttle. So the bike is just a little more eager out of every turn. I think it is well worth the $100 for motocross.

It does not have any effect on half-or-more throttle settings. It does not depend on rpm. It does not boost low rpm power or rob high rpm power. No effect whatsoever on the powerband. It simply helps the bike run cleaner when you open the throttle and when you leave it less than half throttle.

  • Hurricane

Posted February 25, 2005 - 12:29 PM


My buddy and I made them for our 400f's. Bought a thin sheet of polished steel from Grainger for about $3.50 and cut it to shape. Somebody on this site had a template they made with picutes and all, do a search on "powernow" or "home made powernow", it was sort a top hat shape. Then I got a hacksaw blade and cut two grooves in the carb bell across from each other. After that I pressed in the steel plate with a vice. The hardest part was cutting out the plate with a dremmel tool and then smoothing the edges with a file. Also if you screwd up a the carb bell you could get one from the dealer for about $35 so it is still cheaper than paying Powernow $100.
My buddy said he didn't notice much difference on his yz400 but I noticed a little more low end on my wr400. I ride the woods and I noticed I could ride a gear higher in alot of situations and lug the motor a little more. It was definetly worth the $3.50 and a hour of my time. :)

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