I just bought a honda rancher 400 and the dealer was supposed to change the carb jet out for high altitude , I live at 9000 ft. and about a 100 miles from the nearest dealer.
My question is it hard to change the jets, have never done it before and after looking at the engine and carb I do not have a clue how to start.
Also is it necessary to hook up a tack while your doing this .
Anyone have detailed instructions to help me out.
I hate to have to load up the atv and take a 100 miles , if it is something I can do
thanks
new comer olcowboy.

 

thanks a lot for all the help

 

For now, just run with your airbox lid off! It will give you more air, and give you a sort of crude rejet.

My mountain rides start in the valley at about 4,000', then go up to over 10,000', so my ideal jetting changes throughout the ride. I use the Thunder TPI valve (http://www.thunderproducts.com/tpi_valve.htm), which I can open or close as I ascend or descend in altitude, to give a sort of crude rejet. Above 10,000', I just pull the lid off altogether. The system works great for me!

Jetting is more art than science, and is best done by someone with experience! But, if you pack it up and take it to some place that is a different altitude (I'm guessing Grand Junction???), they probably won't get it just perfect anyway.

Get a service manual, and see what jets and needle position it recommends for high altitude. It should have pictures and instructions on what to do. The main and needle are pretty easy to change, but the fine tuning requires a lot of experience and trial and error.

 

You dont have to go to a honda dealer for a rejet. Any brand atv dealer can handle it. Even guys who run small engine repair shops will do it.
Basicly, at high altitudes, the motor is going to be running too rich. So youre looking at a main jet change, down one or two sizes. Then readjust the mixture screw, in, so the idle mixture leans out.
Be aware, that being too rich only wastes gas, but if you go to lower altitudes( with high altitude jets installed), will be too lean and will cause damage, sometimes expensive damage.
The lid trick works very well, and all you need to do, is learn the symptoms of lean and rich, so you know how to react to those symptoms.
About the best jetting article ive seen, is this ONE.
Dont be afraid to change the main jet yourself, it really isnt very hard to do. If you get the factory service manual, or the clymers, itll step you through doing it. But you basicly need to get the float bowl off the carb, and unscrew the main jet, and put the new on in, and put it all back together.

 

thanks you 2 for the help, I think you just convinced me to take it to a local guy here that works on atvs and motorcycles.
olcowboy

 

i just talked to jorgensons ?? cycle shop in Richfield utah about re jetting my suzuki eiger before i go there. was told to rejet to 94% of factory jet. book says i have a # 122 jet. 122x.94=114.68. he said to use a 115 jet an it would run fine. i found one at local bike shop. good luck..

 

How exactly do you change the jets? I have an 05 Rubicon. I have heard it is real easy to strip the four screws on the bottom of it.

 

The screws are very soft and you should probably change them out to allen heads. But rejetting is easy. Just use a screwdriver that fits the screws tight and put some arm behind it and you shouldn't strip them.

 

You asked how to rejet? Its very simple and you shouldn't be afraid to try it. First turn off your fuel and run it out of gas. Then you have to loosen the clamps on the intake and the tube that go to the airbox. Its easier if you remove the bolts that hold in the airbox and move it back a little. It helps give you a little room to disconnect the carb. You only have to remove anything that keeps the carb from rotating. I'm not familiar about the Rubicons, but they can't be much different than the Rincons. Turn the carb upside down and remove the 4 screws from the bowl. In it are 2 jets. The pilot and main. The jet size will depend on where you live and what elavation your at. You could use a Dynojet kit. They have have a chart in them to help with the proper jets, they also come with a new adjustable needle. Or you can run factory Keihin jets. You can get them from Honda or jetsrus.com. The Dynojet kit will cost about $45-60 depending on where you get it. The Keihin jets are about $8 a piece from jetsrus. They also have the allen head screws for your carb.
You should try Hondaforeman.com. These guys should be able to help you with jet sizes for whatever pipe you go with.

 

The four screws on the bottom of the carb, why did Honda make them to where they strip really easy? Thanks for the help. I will try it myself. I know I have to change just the main jet, but which one is it?