Home made Power Now

[beefking]

A little while ago I made a "power now" (divider plate in intake side of carb, reduces to smaller venturi at low throttle=more torque.) for my DRZ and it worked really good at improving low end snap and just generally more torque. The real product is close to $100, so I made my own for free!

I make one for the 89 KDX (stock PWK36 carb) out of a clear piece of plastic, bit less than 2mm thick. It was pretty easy, hardest part was getting the curve just right so it would be snug in the throat. For that I traced the curve with a piece of wire, and transferred that same curve to the plastic piece. Cut some shallow grooves in the carb with a hacksaw blade, made a cutout for the slide, and tacked it in with JB Weld (ain't goin anywhere!)

I took it for a short spin around my yard, and I can tell you it did make a noticeable difference. It also made the jetting (pilot jet anyhow) rich, so I have to drop down to a 40/38pj from a 42 and I think it'll be perfect. I had a bog off idle, or more of a lack of power, but now it doesn't seem to have that! Definetly more low-end chuggability, should prove to be a good improvement in the trails, seems to be able to lift the front wheel a little easier. I have no idea how it affects top-end power, I doubt much if any. This weekend (or sooner) I'll be able to give it a GOOD test ride, see how noticeable it is.

I'll put some pics up in a little while. :thumb:

 

[mcoker]

Cool! Free, homemade mods are the best.

 

[skipro3]

Depending on the thickness of the plate, doesn't that reduce the overall dimension of the carb. Instead of a 35mm now possibly a 33mm?

 

[beefking]

I think you're right about the overall size being smaller, but I honestly don't think it will affect top end as much as having a smaller diameter throat...we'll see though.
Before, with PC pipe, no lid/stock silencer chopped down/+2mm Wiseco/mild porting it ABSOLUTELY RIPPED on top, way more than any other KDX I have ridden. Once I got up in the powerband, 6th gear wheelies weren't even an issue if standing up, 13/49 gearing. This isn't anything great in the woods though, as all that power is useless, so now I'm trying to shift that power down a little. I know an FMF woods pipe will make a big difference, but I'll try making a difference without spending money first! :thumb:

Here's the pic to the mod, next picture is another pic. ;)

 

[procircuit21]

Does the plastic piece go all the way to the throttle slide so its flush up against it?

 

[Simon Fuller]

Any reason you used plastic? A thinner piece of stainless steel would have less of an impact on the diameter, but I would be more difficult to work with.

Great idea, I've got a 220 so would I need to get a carb from a 200 to see maximum benefits from this?

 

[Simon Fuller]

In the RB Designs mod the plate is inserted on the intake manifold side. What is the difference to the RB mod and the power now?

 

[beefking]

I cut the edge of the plate so that it would come almost right up against the slide for the best effect, dunno if it makes a difference.
I used plastic mostly because it's easier to work with, but one I'll change it to a thinner piece of stainless, which is what I used in my DRZ.
I'm guessing using a larger carb with this plate would be most effective, so that you keep low end power and retain top end. But if you put the plate in the stock 220 carb I don't see how it would hurt the power.

I've been thinking about it, and I don't see how running the plate on the manifold side would be an advantage, as the moving air would still hit the slide and have to be forced under it. With it on the intake side (like how I have it) it directs that air BEFORE it gets to the slide. I'll have to try it the other way though, my thinking could be off. ;)

 

[Matt90GT]

Remove the unit before the JB weld comes off! It has happened many of times! You need to find an aircraft grade adhesive that is fuel resistant if you are to epoxy those homemade jobbies