Uni-filter Jetting

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dirtstalker

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I have a Pro-circuit t-4 slip on with a uni-filter. It had a k&n on it when I got the quad and it ran fine. I put the uni-filter on and now it pops at higher rpm's while riding. Never done that before. Un-modded airbox by the way and all stock. Not sure what the jetting is, haven't checked. Is the jetting messed up with the uni vs. k&n? If so, where would be a starting point? Quad runs fine until it gets into higher rpms. Any help would be appreciated!
 
If its a stutter popping like its losing power then its jetted to rich, if thats the case then try going down one size on the main jet from what it is now.
 
Definitely rich. The K&N flows better than any foam filter. Going back to foam chokes it down. I went from foam to K&N with an Outerwears on my 660 and had to jet up a couple sizes.
 
Ok I checked the jets. 150 on the main and 45 on the pilot. So I should just go down a size on the main only? Leave the pilot alone i'm guessing? What size should I go on the main?
 
What altitude are you at? I had a 150 main and 45 pilot in my Warrior with a single stage ProDesign foam and it ran great. I am at around 1250 ft above sea level here. I would try a 145 and see what it does. I bet your altitude is a little different otherwise I would have thought it would have worked.
 
My altitude is around 800-1000 avg. around 9 depending on where I ride at. It runs fine with no filter on it, but I can't ride the trails around here like that.
 
If it runs fine without the filter, I would try a 145 and see what it does. Are you still running with the rubber snorkel on the lid too? The pilot will be fine as long as you are able to get it to idle within 1 1/2 to 2 1/2 turns out on the fuel screw. Temp and humidity will affect jetting but you should be able to find a happy medium that will work across the spectrum. Also the amount of oil on the filter can mess with jetting too. Too much oil will richen things up too.
 
Yea it's still got the snorkel on it. I cleaned the filter off really good and got the oil off of it just to see if that was the problem but it didn't make any difference. I'm gonna go to the shop tomorrow and pick up a jet or 2 and try em out. Hopefully it will work. Thanks for the help. Ill update tomorrow on the outcome.
 
I was running the snorkel as well. I have always left my air boxes intact. If it runs good without the filter, jetting will fix it. Aftermarket jets usually jump in steps of 5. OEM jets if you have access will get you steps of 1. Get you a 140 and a 145 and I am sure one of them will cure it for you. I think 145 is stock so it would seem odd if you had to drop below that. I assume your Uni is a dual stage? Red outer covering and black inner filter? I have the Uni dual stage filter on my Raptor 350. My bud at the dealer said he only oiled the inside black filter and left the outer red cover dry. I also run an Outerwear. The jetting on it is stock and the only mods are the Uni and an FMF Powercore 4 slip on. I have never had to mess with the jetting on it at all.
 
Get a 147.5 main, Im running a 147.5 and a reemed stock pilot with stock exhaust and a uni pod filter. Also check the needle clip setting is stock settings.
 
I agree, check the needle clip position. That might explain the differences as well. Stock is center clip slot. I would check the clip position before getting jets. If it is lower than the center slot, it would make it richer.
 
Alright, I put a 145 main jet in, and it still sputters. Not as bad as before, but still annoying. I'm gonna take the carb back apart and check the needle clip, if it's not in the stock (center) spot, should putting it back stock fix the problem? If it is in the stock spot, which way should I move it?
 
dirtstalker said:
Alright, I put a 145 main jet in, and it still sputters. Not as bad as before, but still annoying. I'm gonna take the carb back apart and check the needle clip, if it's not in the stock (center) spot, should putting it back stock fix the problem? If it is in the stock spot, which way should I move it?
Click to expand...

If you mess the needle/clip heres a quick tip, If you raise the needle drop the clip it richens the motor, so if you drop the needle raise the clip it will lean the motor. Also the air fuel screw will richen if turned out and lean turned in.

Id get a 140 and whatevers between 140-145 so you can try them both. If you going down to a 145 from 150 you could just be one off if you say its close to running good
 
Ok, so I dropped the needle clip down a notch, bike runs fine now. Parts place didn't have anything but a 145 and a 142.5 in today. Will running the bike like this hurt it in anyway??
 
The worst it would do is run a little lean. If it runs good with what you did compared to how it ran with the old adjustments then id say you got it where it needs to be.

Are you testing each jet change and riding to see how better it gets? You can only get a accurate setting with putting the bike under load fyi
 
Yeah I've been riding it about a 1 1/2 miles everytime I've changed something on it. It seems to be running great at the moment. I'm going on a 4-5 hr. trail ride tomorrow, so i guess i'll know for sure what it's gonna be like tomorrow.
 
UPDATE:: After changing jets and moving the needle clip I went on about a 4 hr trail ride. Bike started popping like intake boot was cracked, and sure enough it was. I taped it up to get me home and got a new boot. Put boot on, and bike would idle fine, but it would pop and sputter real bad. I figured maybe the boot was cracked slightly to begin with, and just wasn't able to see, so I moved the needle clip back to center(stock) position. Bike is still popping a lil at high rpms but not as bad as before. And on the deceleration it will backfire a ft long flame out of the exhaust.
Do I need to go back to the 150 jet that was in it? or whats's my next option?
 
Not sure with the popping cause mine did that when i first got it running again but then stopped.
 
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