Idle air control valve. Key off, remove the seat. On top of the throttle body there is a white protective cover. Remove it. Under the cover is a sensor. There are 2 safety torx screws (they have a peg in the center of the torx requiring a torx bit with a hole in the center of it). I have seen guys remove them with a miniature vice grip (not suggested) Once the screws are removed, lift off the mounting ring plate and pull out the sensor, note a notch in the side of the slide assembly. There is a peg in its throttle body bore which it must be lined up with during install. Clean the slide with carb cleaner and spray cleaner into the throttle body bore where it was removed, with a q-tip. New, cosmoline and grease may have gotten to this slide and bore. Later down the road, dirt and grime can build up in and on them making them hang up. In cold weather they can hang from frozen grease causing start-up and backfire issues under decelleration. The port can accumulate fine dirt particles and score the bore once it's dirty. Cleaning it can also save you on expensive spark plug replacement from too rich of a mixture upon start-up from the IACV piston hanging up in the bore.

Hope this helps you

----- Gimpster -----

 

Thanks gimp i'll take a look into this

 

Good tip Gimpster. The IAC is also known to hang up on the EFI Rincons, usually acting up in cold weather with a really fast idle.

Harbor Freight carries bits for tamper resistant torx. Probably not the choice of a professional mechanic, but reasonably priced and fine for occasional user.

Gerkendave, if you do the oil and filter, and clutch adjustment yourself, don't forget to adjust the valves, or have them adjusted.

 

Thanks jeffintd i plan on having a shop do the valve adjustment i already know i can change oil and adjust the clutch (used to have a 99 fourtrax 300). I just want a shop to do the valve adjustment as i don't have much time and not much experience and I'd like it done right (spent the money on a new machine would like to keep her nice) thanks for all the help guys much appreciated

 

Be sure you put the oil filter in the correct direction. The rubber gromet seats onto the nipple on the cover, and the spring maintains the tension. The stock one is well marked, but aftermarket ones may not be.

Believe it or not, over the years we have seen a few folks mess this one up and end up with a top end starved for oil!

 

Thanks for the tip i am very careful whenever i do anywork on any of my stuff. I have performed many repairs including replacing heads injectors etc on my pickup and have changed the oil in my old 300 a few times so i'm pretty sure i am capable but thanks for the good advice. I used honda oil and a filter from my honda dealer in my 300 what do you recommend for oil in the ranchers. I'm in nebraska and its pretty cold (30 degrees average but up to 50 and 60 an down to like below zero some days in the winter) thanks again

 

Always pick an oil that is motorcycle specific, API SG/JASO MA. Beyond that, the blends and synthetics have advantages over plain old petroleum oil, and the ester synthetics have advantages over the other two types of synthetics.

I have studied up on this (I am a biochemist), and the absolutely best oils out there are the ester synthetics....but they are expensive!

My preferences are Redline MC and Maxima Ultra. I am seeing an increase in torque/horsepower running Redline, which contains organic friction modifiers, but they will not make your wet clutch slip like inorganic modifiers like moly. It is very slick, JASO MB (and an exception to the MA rule wet clutch folks are so use to). Maxima Ultra also contains organic friction modifiers, and a references below has a dyno showing the results.

In warmer weather I like Redline 10W30 and 40. In cold weather, Maxima 530MX, and in extreme cold, Maxima Ultra 0W30. Maxima Extra is also an excellent oil, but is not friction modified.

 

Lots of good reading:

http://www.thumperfaq.com/oil.htm


http://www.sportrider.com/tech/146_0308_oil/index.html


http://www.sportrider.com/tech/146_0310_oil/index.html

 

Which side of the 420 do I start taking off panels? Is the drain plug evident on the bottom of the crankcase? And from where do I refill the oil, is there are twist off large cap or do I tilt and refill in the small yellow caps?