This is a mod for those leaky ATI valves, and it will work with the good ATI bypasses also to make them close sooner.

Do not screw the pilot jet into the connector. Just push it into the hose, the threads help hold it in, if you need to massage it with a grinder a tad to get it to go in by all means. Just shove the hose connector in to press the pilot jet in further into the hose, then connect the other end.
Like this:
=-=


Funny thing- my truck is 3.55 and 31.5" (265/75/16's) tires too..LOL with a 4.6L and it extremely sucked on the highway before this. Now it is a lot more driveable with the 9lb pulley.
Having a 12lb pulley will make this mod even better.

 

Called local Bike shop and the smallest size jet they have is a 15. Do you know the diameter of the hole in the jet? I will make my own. Or a part number?

Thanks

Jean Marc Chartier

 

Press the threaded end in to the rubber hose 1st if you are using a pilot jet.

The local yamaha shop had a complete selection of mikuni pilot jets.. I don't have a part number. A 15 would work just fine too, just put it 4" away instead of 5". Pilot jets are cheap so you can try different sizes and that will change when the valve closes. Smaller for sooner...

 

Another thing you could use is a mig welder tip. Just have to play with the sizes, to get the desired response.

 

Oh, so the hose connector is just used as a tool to push the pilot jet into the hose?

So just install the pilot jet in the vacuum line 5-6" away from the bypass is what you are saying? Which way should the pilot jet face....threads towards the bypass valve side?

and is this the same style Mikuni pilot jet you are using? I'll get size 12.5 off of Sudco.com


Sorry for all the questions, I don't want to vary too much from the way you have yours set up.

Thanks again!

 

Thanks. I will go somewhere else to find the 12.5.

 

Post your results please guys. I to have about a hour drive to the nearest location where I can get a pilot jet from, Kinda of a joke considering how many I have sitting at my dads place about 3000km's away.

I would like to try this. I am waiting on my blow through MAF and I'm also going to move the IAT from where ATI puts it and move it to where JMC has it.

My hope with the blow through is that I can run a blow off valve to Atmoshpere and with my 12# pulley cap it off at 10psi. I want to stick to 10psi because I don't want to blow my old motor before I can get a replacement built.

Thanks for bringing the thread back!

 

MX'r most pilot jets look the same, that will be similar to the one you want. And yes the hose connector is used to connect the hoses and to shove the pilot jet in a little further. Thread toward the bypass side, but either way it doesn't really matter.

I moved my IAT to before where the bypass enters the airflow. I haven't put a tune into my truck yet.. So for the best performance without a tune then before the filter is the optimal place to have it. With a tune right before the TB is the best because you can tune for the IAT's. If you left it untuned and put it there the truck would be very lazy because the spark would be extremely retarded.

I'm not a huge Ford fan really, this is my daily driver and from the power it had stock.. It sucked! Now it is how it should have came factory! There is still more to come for mods... I am going to take it to the local chassis dyno I tune at and start beating on it. I wasn't planning on messing with this truck that much, but with the cost of a new one. This one will do just fine for now...

 

I think I have completely missed what you are talking about until now...I just realized lol. Sorry if I have been a little slow in my understanding.

So the pilot jet is completely shoved inside the hose and the hose connector itself joins the two ends of the hose back together (that's what a hose connector does duh )?


I was under the impression before that the pilot jet itself was pushed half into one end of the hose, and half into the other end thus acting as its own connector. But I think what I said above is what you are trying to explain to me.

Thank you very much, you've been extremely helpful!

- Chris

 

No Problem.. I wish I would have found out about this sooner, I was extremely disappointed with the performance of my truck after the S/C.
With a tune and a bigger pulley.. watch out positive displacement S/C's!.. Or at least make it seem like one.

 

Same here, I was less than impressed with the power gains from the Procharger under civilized driving conditions....and i'm tuned at 12 psi. I really don't feel like flooring it everywhere I go to feel the benefits of a blower...it's a truck after all. I really can't thank you enough

As for the other members looking for this pilot jet, it sucks some of these websites don't ship to Canada. I was just going to order the jet off a website like jetsrus.com or sudco.com, but I see they only ship within the continental US The internet is your friend! If I find a place that ships to Canada i'll be sure to let you guys know

 

I'm guessing by your name (NacsMXer) that you play with Dirt bikes. Just go to your local bike dealer and they should have a assortment of pilot jets. I really think this is a great idea, and if I have to head out to Abbotsford for some Mustang parts them I will stop in at the Yammy dealer and get a jet.

 

Any local bike shop should have a Mikuni pilot jet selection... Shouldn't matter the brand since most have ran a Mikuni at 1 time or another.

Just a review for people reading on doing this mod and what it accomplishes:

If you run a stock ATI bypass or most any other bypass this will make the vacuum it takes to keep the valve open less. So when you lean into it the bypass will close sooner giving you the benefits of the blower at a lower RPM. The bypass will start closing when you come to a hill or lean into a little off of a light.
This will not however disable the function of the bypass, it will still relieve pressure when you let off or the load decreases. At low RPM you don't really hear the psssh sound of the bypass opening since the blower isn't creating a huge amount of boost. Just enough to help the engine out when its labouring and loosing vacuum... and unlike the stock setup it won't close until it looses pretty much all vacuum.
Adding a bigger pulley to the blower and this mod will help the down low performance even more so. I will add my 12lb pulley soon then going up the big hill in town it will sit in OD locked up still!

 

Yeah I actually ride MX on quads but I mess around on dirt bikes once in a while...gotta love toys! My local dealers are really hit or miss on jet selections, i'm lucky if they have a simple main jet in stock without having to order one. Depends on where you go I guess. I just bought the Mikuni 12.5 pilot off of Ebay for $4.95 with free shipping, can't beat that

 

dart440 do you get any impellar surge with the valve installed? like when using cruise control or driving in traffic?