AP MOD ? 06 yz 450

I keep hearing about this ap mod is this a safe thing to do to your bike? why would nt the engineres disiign it with some type of direct linkage syst in the first place? Is this old news is everyone doing this now? how well does it work?

It works great.Honda basically changed their linkage system in their carb for 07 that makes it like the AP is already wired.Its pretty cool.

As for it being safe I would say it it.

I heard about the Hondas. Are people wiring the 06 Yam ac pumps too?

I have been struggling with whether or not to do this for months. I have an 06 YZ450 that has a 170 main and 48 pilot and it runs perfectly. I have read what seems to be all that has been said on the subject, and tonight I took it apart to see for myself what it entails. After taking off the tank, subframe, and shock I was able to get at the carb. First I was happy to see that there is no gap between the linkage and throttle when held wide open (something that must be check before wiring closed). All that was required then was to wire it up and change the leakjet to a #70 (which I don't have). After staring at the carb and watching the AP squirt about gallon of gas (quite entertaining), I wondered one thing. With the AP wired, the duration would not last as long as when the AP was not wired. While I could appreciate the gains of instant throttle response when wired, I question what affect the duration being shortened would have. After all this I check my valves (right on the money after 60 hours of racing) and decided to leave AP alone and put it all back together. I am a big fan of making things faster and better and I know guys have had great success with this mod, but I'm just not 100% sure for my bike. It runs GREAT right now, so why F it up? Whether I'm in a rythm section, landing off a big hit, or coming out of a tight turn, it never bogs and runs crisp. While it will never be a 2-stroke, I'm not sure that is what I want anyway. Instant response means wheelspin for me most of the time, and I don't want a ton of wheelspin. The great thing about 4strokes is there ability to hook up. Maybe that milisecond of delay is better than the instant 2stroke response. This is far and away the longest thread I have ever written, and for those of you that have hung in there up to now, I thank you.

Is anyone else almost loosing sleep over this one?

I Want To Do This To My 04 But I Have The Same Issue It Runs Great Allready And Dont Want To Mess It Up. So The Only Problem I See Is The Leak Jet. My Bikes Jetting Is Perfect , And If I Do The Ap Mod With The Wire And The Diaphram Mod Then What Do I Do With The Leak Jet,do I Just Go Bigger Or What

The mod is 100% reverseable.Just try it.If you dont like it snip the wire and your out peobably out 2 cents worth of wire.If you like it which I bet you will just keep it on.Also you dont have to remove the tank or anything to get to it.

I did mine and i am glad I did. Never changed the leak jet, didn't see the need.

Good point on it being easy to undu by just snipping the wire. No leak jet change and it ran well? Guess I will have to try it. Back to the garage.

The 06's AP squirt is much too long, so performing the mod :

1. Shortens the response time giving an instantaneous squirt, which is what the AP is meant to do.

2. Increases AP squirt pressure (squirting more fuel in a shorter amount of time) This requires that you increase leak jet size in order to bleed off the unneeded extra fuel that is a by-product of directly linking the levers.

Doing the mod on the 06 really cleaned up the bottom end response. The bike never had a stumble, it just seemed sort of sluggish off the bottom. So doing the mod cleaned the bottom end response and gets you into the mid range power quicker.

So what do you need to increase the leak jet size to when doing this mod?

Baron Von Beard, you the man. Thanks for the help.

Sean06 crack open the float bowl and change the leak jet to a #70.


So what do you need to increase the leak jet size to when doing this mod?

Pull the float boel and you'll see a small brass jet in the bottom of the bowl itself. Unscrew it and screw the new one in. You'll need a small flathead to get the jet out.

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