AP MOD Leak Jet

[kjwcoyote88]

I have been doing alittle research on the ap mod, and it sounds like a pretty awesome idea, and I would love to try it. Can anyone tell me what the best size Leak jet to use at 5500ft above see level is, I know alot of guys are saying 90 or 100, maybe? Also how do you set the AP Timing GAP. Do I just set it to .100" like the AP MOD instructions said? Any help on this would be great. Thank you

[crf-f crf-r trx cbr]

wire it tight.....put a 90 in and a 05 crf250 diaphram......or shave the stock one down to 2mm......this mod is so badass on my 03....what year you have?

[cjmx]

I have the JD jetting AP kit with the everything included that I never used. Brand new in the box. PM me if you are interested

[00drzs]

did the o-ring only on my '04 and the bog was gone. Bought the leak jet and never put it in, I wanted to change one thing at a time:thumbsup:

[ZaneTrain13]

What does this AP MOD actually do?

[orangyktmthing]

What does this AP MOD actually do?

Here is a link to the sticky.

https://www.thumpertalk.com/forum/showthread.php?t=374181

[Santan9]

what exactly a leak jet? is it the same thing as the slow jet/pilot jet?

[orangyktmthing]

Thumperfaq can explain it better than I can, so I give credit when credit is due. "The AP provides a “squirt” of raw fuel into the carburetor venturi when the throttle is wicked. It richens the mixture to run best at lower speeds, yet allows a leaner top end for more over rev. This system has a jet called the leak jet which controls how much of the AP squirt is redirected back into the float bowl instead of into the carburetor." So essentially, the leak jet is there to redirect unneeded fuel that the accelerator pump pumps in and puts it back in the float bowl when the engine is at higher rpms. I am sure someone will correct me if I am wrong.

[kjwcoyote88]

wire it tight.....put a 90 in and a 05 crf250 diaphram......or shave the stock one down to 2mm......this mod is so badass on my 03....what year you have?

I have an 06, so the 90 leak jet is fine for my elevation?? I cant wait to do this mod!!!? alot of guys say how much it helps, Also will I have to change the jetting or anything else on the carb, and Im a bit confused with the AP Timing Gap. How am I exactly supposed to set this?? thanks for all the help!

Edited April 9, 2010 by kjwcoyote88

[Santan9]

Thumperfaq can explain it better than I can, so I give credit when credit is due. "The AP provides a “squirt” of raw fuel into the carburetor venturi when the throttle is wicked. It richens the mixture to run best at lower speeds, yet allows a leaner top end for more over rev. This system has a jet called the leak jet which controls how much of the AP squirt is redirected back into the float bowl instead of into the carburetor." So essentially, the leak jet is there to redirect unneeded fuel that the accelerator pump pumps in and puts it back in the float bowl when the engine is at higher rpms. I am sure someone will correct me if I am wrong.

perfect, thank you very much. I know exactly what he is talking about. +gas to you

[fxrs]

Can you use an adjustable leakjet with the mod?

[kjwcoyote88]

Can you use an adjustable leakjet with the mod?

Thats a great question?! Does anyone know if that will work??? As far as I can tell the R and D Power Pump 2 adjusts to the equivalent of a #10 through #70 leak jet. Can anyone confirm that? Also, where on earth do you find a #90 leak jet for this mod, Im having a hard time finding one.

[crf-f crf-r trx cbr]

carbpartswarehouse.com or yamaha yz250f part

[kjwcoyote88]

carbpartswarehouse.com or yamaha yz250f part

Does it matter what year yz250f?

[crf-f crf-r trx cbr]

nope.....a 90 is a 90

[kjwcoyote88]

Alright, so I order the yamaha yz250f #90 leak jet, should be here next week sometime. I shaved down the AP rivet and safty wired the lever. I cant wait to test this out!!! I shouldnt have to adjust the other jets or anything, right?