I got the jets from a Yamaha dealer--just regular Mikuni jets....

DOO800

 

the jet kit that is in the k&n power kit is supplied bt dynojet.

 

and it will NOT include a 147.5 main jet -- it has a 150 and 155 both will be fat in the warmer weather. Any Mikuni style jet, with the right # has the correct hole..

 

here's my setup, 98 wolverine proflow kit without the outer rap,ids pipe all 12 disc installed,dynojet kit with #155 jet and a extra air snorkel. i ride at 500ft above sea level, and yes it runs a little rich but it makes good power and cranks and idles like greased lighting.

 

Ok I ran pretty hard today to see what the problem is. It seems to cut out at the topend of 3rd gear and seems to be choking for air when full throttle. I used the #155 jet and I think the third notch on the jet needle...should I try to adjust the air jetting..can I get to it without taking the carb off? I checked the plug and it seems to be running a bit rich...Should try adjusting the jetting valve and air valve first or should I take the carb apart and move the disc on the needle down a notch?

 

Howdy shoey...is the spot where it starts acting up worse when it's cold? if it is your lean....if the problem gets worse after it's warmed up your rich....give this a try and let me know what happens...restrict the air flow going into the engine by using duct tape...tape the holes closed that you cut in the airbox and test drive again...if the problem gets better you are lean...if the problem gets worse your rich...I'm thinking your running rich at mid to top end....if this is the case you will have to take the carb off to change the main jet down from the 155 your using to the 150...while your out testing it check the plug color by running at full throttle in fifth gear and hold the throttle wide open and shut the key off...don't let the throttle go until the quad has stopped...release the throttle and check the plug color...let me know what you find...
BB

 

Ok I put a new plug in then covered the holes and let it warm up for about 15 min. I could tell that it was definetly choking for air when I just let it idle and reved it up. So I ran it and it was worse. I checked the plug as you instructed and there was some white/grayish residue on the plug tip...looks to me like I am running a bit rich. Here is my biggest concern. The atv seems to be running the same as is did with the stock pipe as compared with the new FMF Megamax II. I put the jet kit on first a few weeks ago and just recently put the FMF pipe on. Should I not be getting a better response from the new pipe or is the jetting not allowing me to use the pipe's full potential?

 

Howdy shoey....white colored plug means your running lean....remove all the tape covering the holes and run it at full throttle again and check plug color...I'll bet you the plug is still white after you test it again....the perfect color for your plug is a redish brown color.go to your local yamaha dealer and buy a 157-1/2 and a 160 jet...they should be around five bucks a piece...remove the carb and put the 160 in and test drive it again...then check the plug color...how does the quad idle?...the air screw under the carb adjusts the smoothness of the idle...check the throttle cable where it goes into the piece of rubber at the carb to make sure it is in all the way...let me know what happens...don't worry all the hassle will be worth it once it's done...mine runs better with the pipe and yours will also...
BB

 

Hey BB,
Well I went in and moved the needle clip down one notch and ran it. It seemed to bog down a litte in 2nd & 3rd WOT. So I messed with fuel mixture, but no good. I moved the needle back to the 4th notch as recommended and adjusted the fuel mixture. it reallys seems to idle good at this positon. I may try moving the needle up a notch later to see what it does. I am still using the 155 jet but may try to go to a 160. thanks for your help. I know 100% more that I went into the Carb myself and started messing with it. If you get any more ideas let me know. by the way Underneath the carb where the fuel mix screw is what are the two screws on each side of it? Can these be adjusted?

 

Howdy shoey...the first thing you have to do is change your main jet to a 160....from what you have been telling me the problem happens at 3/4 to full throttle...what gear it's in at that moment doesn't really matter...what does matter is the position of the throttle...you say it starts acting up at full throttle...the main jet is what supplies the fuel at full throttle...that tells me it's your main jet...when you cut those holes in the air box your letting the engine take in more air...too much air and not enough fuel will cause it to bog and that would account for the white spark plug (lean burning)...leave the needle in the notch it's in right now and reset the air screw to what it says in the install papers...let me know how it runs after you change the main jet...
BB