Power Now - Affects Jetting?

[spokes574]

I am thinking about purchasing the PowerNow and PowerNow Plus by Scary Fast but am concern I will have to go through the whole jetting thing again.

I finally got the jetting figured out on my CRF450R, Pleasanton CA.

Does anyone have any experiance with the Power Now on 4 Strokes?

Once installed both intake and out take did you have to rejet?

When I installed on my CR250R I had to go up two on the main.

Thanks,

Spokes574

[Dave Hopkins]

I have used the Power Now on several bikes, never tried the "plus". Some will have different opinions but my thought is, it does not make more power and it does not change jetting. What it does do is make your carb work better and starting is better. The bikes that benifit from it are the ones with big carb related to engine size as what the PN does is direct the air flow more toward the jet at low throttle openings

[burgunder]

I just installed the powernow, but not the plus on my 03 yz250f. At the same time, I installed a jd jet kit which is just a needle and main jet but no pilot. My bike always started easily hot or cold. Now, it is even easier (if that makes sence.) My air screw only changed about 1/4 of a turn, but that could just be the conditions (temp and humidity.) I did a small bit of testing on the mid and high range, and the bike could be riden as it is. This is probally irrelavant because of the jet kit I installed, but I would say that you could install the powernow without rejetting. If it does change the ratio, I think that it would only be slight, and could be resolved with a quarter turn on the airscrew, 1 or 2 neddle clips, and a size up on the main at the very most. I would go for it.

[spokes574]

Thanks.

It makes sense that starting might be improved.

I ordered just now the combo.

Boysean is working on one and see's ~1/4 - 1/5 hp

gains from low to mid. They also said that the exit side of carb

with the device really does not help with performance based

on thier testing. Thier version will not be out for another 1-2months and I can't wait that long.

Thanks,

Spokes574