[JS450X]

I think I'm on the right track but I value your guys opinions so I want to bounce this off ya. Just got my JD jetting kit & STR fuel screw for my 06 CRF450X. I have cut the side vents on the air box, backfire screen removed, full Pro-circuit T-4 exhaust / header. I will be mostly running in sea-level to 5,000 feet (California), temps right now are around 55-70f. Based on what I read I think I should go with red needle / 4th clip position, and the 170 main jet. Does this sound right? Also, if I install this new STR fuel screw do you think I need some major turns one way or another based on all the above?
Please let me know as soon as possible guys, leaving Friday.

[JAWS]

You're right on track. If you have the stock pilot, then you will probably need to be out around 2 turns on the fuel screw. Did you block off the smog? If so, you may need to go up on your pilot. If you have decel popping remove or block the smog. If the smog is removed then try opening the fuel screw 1/4 turn at a time and see. If you get out to about 2 1/2 turns, then go up on the pilot one step and turn your fuel screw in to 1 1/4 to start. Adjust from there. After the smog is removed or blocked, decel popping is a sign of pilot leanness.

BTW, you might look at the jetting forum and the results from areas like yours for info.

Joe

[JS450X]

Alrighty, I did the fuel screw, needle and jet and it was relatively simple. Started it up and it seems to run just fine however I only rode it up and down a block on pavement . Going to take it to Gorman on Monday so we'll see. The bike was supposed to be jetted up from the Honda shop when I had them install a Pro Circuit exhaust when new. The main jet I pulled out was a 148,,,isn't that stock? I was a little apprehensive stepping way up to a 170 but I did it. I also turned out the fuel screw two turns to start,,,think it was approx. 1 1/2 before. Just riding around here I did notice it wasn't popping or back-firing or showing any black/blue smoke. What are the signs I should look/listen for if 170 is too big? I will bring the JD kit with me but hoping I won't need to mess with it. If it starts running too rich should I start with turning the fuel screw in or just yank the 170 and try a 165?

[JAWS]

Good job! I suggest that you run it until it's hot. Pull the plug and check the color as a base line. Then, if you really want to know how the jetting is doing, you will need to make a few runs at the throttle position that is most affected by the jetting you want to check. So, for a main jet check, run it in 2nd gear, well up in the r's range (3/4 to almost full throttle), for a about 5 seconds. pull in the clutch and hit the kill button (don't let the engine idle down). Pull the plug and "read" it. If it is somewhere between a light tan and med brown, then you are good. If it is black, then you are too rich. If it is white, you are too lean. Same process for the pilot. Just run it at less than 1/4 throttle and check. If your pilot reading is a little too dark, try closing the fuel screw 1/4 turn and try again. You should be in a range of about 1-1/2 to 2 turns when things are about right.

If the decel popping returns, just open the fuel screw another 1/4 turn. If you get out to 2-1/2 or more then you need to try the next pilot jet up in size.

Bear in mind that higher altitudes have thinner air, so you may run a tad rich in Gorman. If you ride a wide variety of altitudes, then the 170 will work well for you. I, and others, have run Gorman and Kennedy Meadows with a 170 with good results. The plug will tell you.

Joe

[JS450X]

Alrighty Joe, good advice thanks. It was popping pretty good during engine braking but seems to run pretty strong. My first action, based on what you said, should be to try a 1/4 turn out on the fuel screw right? I will try that and if it doesn't cure it I will run through the plug procedure you described.
That was my first Hungry Valley trip and it was pretty good riding. Took all the black trails I had time to hit,,,enjoyed one called "Bad-lands". I wanted to head up into the surrounding mountains but kept running into locked gates or fences I'm sure if I was with someone who is familiar with the area I would have saw a lot more. Cya Joe

[JAWS]

You're welcome. Yes, turn the fuel screw out 1/4 turn and try it. If it still pops turn out another and try it. Keep going until you get out to 2-1/2 or so. If you are still popping, then you may want to try the next step in pilots. Another thing to make sure of is that the carb boots are tight. Any air leaking in the engine side will skew the results (not to mention the possibility of dirt in the engine! ). Don't forget to return the fuel screw to 1-1/4 if you change the pilot. Then you have to start over. I have also found that I need to tweak my fuel screw a bit when it's cold out vs. hot. Usually just a 1/8 to a 1/4 turn takes care of things in that event.

Joe