What number is the main jet on a 250r cause I have to go 2 higher recommend by the person who does my port work on my cylinder and is it hard changing a main jet

 

If it is a 87 TRX 250R Stock main jet is a 150. It is not hard at all simply unhook the fuel hose, loosen the carb from the rubber boots, turn it so the drain plug under the carb is facing out and unscrew the plug. (Gas may drain out) Staring you in the face will be the main jet, it is gold in color. Make sure you use a propper tool or a socket that fits perfectly snug, unscrew the jet and install the new one. Reinstall the plug and the fuel line, make sure those boots are nice and tight, Fire it up and go ride!!

 

What year is your 250R? All years are different. I assume it is a TRX and not ATC. You need to give more info.

 

It is a 86

 

Check out this link. You should find what your looking for.

http://www.macdizzy.com/images/carbu...asket_sets.gif

 

Here are the stock sizes for main jets.
86--.150
87--.152
88--.158
89--.158
Stock carb jet sizes are .150,.152,.155,.158,.160,.162, etc.
If you have a .152 and want to go up 2 sizes, get a .158.
You don't need to do any real work to change main jets, and trust me, I've changed about a million of them over the years.
Get a 17mm box wrench. Then either get a jet tool or get a 6mm socket and a 1/4inch drive ratchet.
Now, shut off the gas. Feel the bottom of the carb, that big hex head is 17mm. Take it out and keep it clean. Then put the 6mm socket up the hole that plug just opened and get it on the jet. Take it out.
Then next step will be easy if you get help the first time. Have someone hold the throttle wide open to keep the needle out of the way while you very patiently put the new jet in. Don't force it or get pissed-off, just take your time and do it. Don't tighten it with much force, just get it snug. Tell your friend to let go of the throttle and then put the plug back in the bottom of the carb without giving it 100 ft.lbs. of torque, just good and snug. Turn the gas back on and go.
When you've done this a bunch, and with a 250R you will until you get it right or you change situations, you'll be able to do this out in the field without even looking at what you're doing.

 

Unless you bought the machine brand new noone can say for sure what size main jet you have,someone else may have changed it.The correct procedure would be to remove your main jet following the instructions the other guys posted.Read the size on the side of it and get one two sizes larger.
Assumtion is the mother of all f--- ups don't assume your main is stock verify it.

88' 250R many extras