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Jetting issues

5K views 11 replies 4 participants last post by  Hunterworks 
#1 ·
Hey crew I have a question about my jetting's, so to begin I have a Dnyatek CDI set in curve 1,AFE air intake,Muzzy full dual exhaust, and the dnya jets kit. So my problem is at WOT the motor starts to jump as if it's hit it's rev limits,it's marking 58 on dirt road, so I let off to half throttle and it stays at MPH and still jerks. My carb setting are 195 front and 190 rear,clip in the second position on the needle, 3 screws out on fuel/air screw it has a lot of power and rev good thru all speeds, I'm just not sure if I should go up a # on the jets or go down a # on the jets. I went to San Felipe last weekend and the Teryx had so much more power, then the Rhino or the RZR's and it floated across the desert with no problems till I hit the long straight aways. I went about 75miles at over half throttle with 3 adults(sorry Jenny who was in the rear bench seat) a lot of Tecate and and still maybe had a gallon of gas, very good I think.

Thanks for your help Roman
 
#2 ·
Romdogg,

The springs in the Dynojet kit are for a stock air box and the air box you have makes the intake system lose the vacuum it needs to operate the slides and pull fuel thru the main jets like you need.

I have a AFE here I am going to test out more but when I put it on with our jet kit and springs it went very lean, it is not because of the additional air flow but because of the loss of vacuum and therefore not as much fuel was flowing thru the main jet.

Your problem may be too rich on the top end. Hard for me to say until I fully test the AFE out to see if it works which I don't think it will and if it does what springs and jets you will need to make it work. Your other choice is get a air/fuel ratio gauge and you will know.

Todd
 
#3 ·
HW I would like to hear what you find out, I have taken my AFE back off because I could not get a good jetting or rod setting at all. I have a sensor and I can get either the bottom or the big end right but not both. Our elevation starts at 6000 then we go up from there. If I get the bottem end and mid range right then it wont pull on the big end, or visa versa.:confused:
 
#5 ·
HW thanks for the incite, so would you suggest I replace the stock springs and keep the Dnyojet needles in or what would be the best in your opinion right now, also I'm getting the coils from Dnyatek will this help with the jetting issues or create a whole new one. Thanks again from your response and look forward to clearing this jetting issue for all of us.

Thanks Roman
 
#9 ·
So from what your info tells me the point here is that the AFE product is not doing what it stats or that it's to much air flow for the fuel system to work properly. So then in order for the motor to run successfully I need to change my air intake or this is were you state you need to prove a point by making concrete facts that the AFE product does not work for the Teryx with mild set ups or any set up be it be big bore,port n polish, new valves, or cams or high compression piston, so just cut my losses and purchase which product to make my motor run crisp? Well I hope to get this figured out soon because next weekend is Halloween a big weekend to open up this desert season. The motor seems to run good just have issues in top end if I have the wrong item can't wait to see what this baby can do with the right air filter set-up.

Thanks Roman
 
#10 ·
Not exactly. I am not targeting AFE. I am of the "opinion" that ANY aftermarket intake replacement is waste for one reason and one reason only. We have vacuum operated carbs and they don't work effectively with a open air intake.

Take a mechanical slide carb, you would in theory just clamp on a filter to the intake side of the carb and be fine but not a vacuum style.


I also won't say that somebody somewhere can make them work or think they can and are happy with one, but I guarantee you, you can do it with a stock intake too with slight mods.

These ATV engines won't digest as much air as these aftermarket intake flow.

I will tell you this. You can add the largest free flowing air intake you want on these engines but you will still have to choke it down where the air comes in at to maintain that slightest bit of vacuum necessary for the slides and jets to work properly, period.

Think of a straw and you drinking water out of a glass with it then I come along and drill a 1/8" hole in the side of the straw. Guess what happens. You can't suck water because you lost your vacuum.
 
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