I bought a K/N air filter I wanted to use to replace the airbox on an arcticcat90 (taiwanese)similar to DRR,Kasea. It has the airbox under the seat with metal tube down to carb via rubber elbow. But I never could get it to run right any suggestions?? It had a 77.5 main jet stock I tried an 80,82.5,85,87.5,and a 90 main jet. It seemed to run ok at first with the larger jets but then would start to bog at low rpm within maybe 5 seconds and unburned fuel was building up on the filter side (not engine side) and I'm assuming bogging down engine. Anyone know a fix?????

 

Did it run correctly when stock?
Why do you feel it needs a bigger jet?

 

my son has a 90 preditor i have put the fmf pipe and the k&n filter on it and i am at a 149main jet just to get the thing to fun, we had to drill the jet to make a 149 seems to run good

 

srpreditor is leading you in the right direction. You are not even close to big enough jetting once you remove the airbox. We had to drill jets also at first, but then I found some big jets (very hard to find anywhere).

The next problem you might see is that once we went above about a 100 main jet, the thing would run fine and then start misbehaving. Finally figured out that the needle seat would not pass enough fuel to supply the main jet, thus running bad once the float bowl got low. The main jet hole was bigger than the needle seat hole!

Happy tuning
222

 

thanks trailblazer, one other thing on the neddle valve i had to lower the clip to the bottom try that with a 149 jet, with a k&n filter that should work for u.

 

I just bought my son a brand new ac 90 a couple of months ago. I hate to say it but I have had nothing but problems. My first problem was the stupid dealer that I purchased it from put mixed gas in the tank. I had to take it into the shop to have it figured out. Then the next problem we have been having is similar to what maybe one of you are having. When he is riding and he has it pinned for any amount of time it seems to run out of fuel. It just starts bogging and if you keep pressing on the throttle it dies. I took it to another dealers service shop and they took it apart and said that it had junk in the carb. Don’t know how it got there. So I thought it was fixed. WRONG! The first time my son had it out the same thing happened. What do you guys think it is. I'm tired of forking out money for a brand new machine. That's why I buy new things, so I don't have to fix them.

 

i think u need to remove any jumpers from the cdi, there is a metal clip between two screws, remove the clip. change the plug, remove the oil tank and premix the gas yourself so u know what the mixture is i would say 32 to 1, thats what i fun in my 90 preditor have had no problem with fauled plugs, use premium gas, and always buy it at the same place it makes a differance, if this dont work let me know.

 

Hey srpreditor what drill bit number or size did you use to get a 149 mainjet?? It'll let me know about where to start.

 

Hey bendman I wanted to answer your question. Yes the ac 90 ran good after I took out the restrictor out of the carb that only let the slide go half way open. Before that I was ready to get rid of it as I took mine to the dealer too. I also removed the inner/smaller little pipe from inside the muffler endcap by grinding it out(after taking off endcap). This still leaves you with the larger 3/4 inch pipe and looks stock. Then I rejetted up 2 sizes to a 82.5 and that really picked up the power. Like maybe 50% more power and costs $3. I was just getting greedy wanting more power by trying to use the K/N.

 

fastdad that is a size 53 hope it helps