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Quick question

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After doing some research on which jetting to start with, does anybody see a problem with the following jetting.

Bike

2003 yz250f with fmf titanium 4 and power bomb

screen out of air filter basket

uni air filter

PowerNow

stock plug

Jetting

Jd jetting kit

Red needle 4th or 5th clip (I forget but as per instruction)

185 main

40 leak jet

stock pilot

ziptye screw about 2 turns out adjust as needed

Location

Pittsburgh pa

75-95 degrees mainly 90-95

very humid

Thanks for the help, I just want to make sure my initial setting are close before i do all the work.

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Sounds pretty good. You might find yourself slightly rich with the 185 main jet. Test it out, then try a 182, and a 180 comparing the top end under load. I run a very similar set up only with a stock YZF pipe. Your FMF might breathe a bit better so the 185 may be OK. I ended up at 180 summer and 182 when it's cooler.

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I live in Clearfield PA.

I just spent two weeks jetting my 06 yz250F.

I found the 185mj is way to rich. I ended up using my stock 178 MJ, a 40 pilot, 40 leak jet, and the red needle on the 4th clip. My fuel screw is turned out 2 turns. I also have the heavy JD oring installed on the AP linkage, and I adjusted the AP so there is no free play in the linkage. Try starting with your stock MJ. When I had the 185, & 180 installed the bike felt sluggish. I didnt have the pull I had with the stock needle and stock jet. I couldnt get rid of 3/16 sputtering with clip positions in the 3 4 or 5 area.

I have jetting 5 bikes now. I have found in every case the recommended MJ size is too rich. Maybe its just being lucky living in PA that this is the case, or maybe the Jetters error on the rich side for legallity reasons not to get sued for cooking someone's engine with a leaner initial starting point.

I have a posted a question to ask those more knowledgeable than I if my settings are lean. The bike flat out tears with these settings. Maybe watch my Jetting: These setting ok (JD Kit) post and see what others have to say.

Greg

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Thanks for your help. I have 180 main in now with just titanium 4 and power bomb which seams to be very close. I will try all others since jetting is testing. I just needed a good place to start. Once I get all of the jets in with the power now, I will report back. Thanks again.

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James recommended, for my case, trying the 180 mj again. He said my current settings are with the red needle, 4th clip, 178mj, and 40 pilot is not too lean. I still have the stock can on my bike.

I'm gonna ride it for a little bit and see how it works with the changing weather. When and if it cools down some, I might be a touch lean.

I know on my 06 wr450f, im at a 168 (stock was 165) and I have the red needle on the 5th clip, with a 48 pilot (stock was 45) and it runs great. Has run great all this season so far.

I'm thinking the 180MJ might be a better all around jet, but time will tell.

Greg

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The 06 YZF's jet very differently from previous years. What works on your 06 is unlikely to work on earlier models. As you say, testing will tell the tale.

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I see you have an 03. My friend mark has an 04. We have done our jetting together. He would change the main, see how it runs, I change the needle since his main change didnt work, visa versa to save tearing both bikes apart and making the same changes. My 06 pulls harder than his even at the stock settings, but his bike hits harder in the mid.

Even though the model year differences, both bike are acting similiar.

His bike stock had a 180MJ with a 90 LJ, mine came with a 178MJ and 80 LJ stock. I haven't talked to him, but he installed his stock 180MJ, put his red needle to clip 5, instead of blue #3 with the 40 pilot jet. I'm gonna give him a call later and I hope he gets a chance between showers to take a test run or two. I will let you know how his bike performs.

Greg

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I went to Marks house and his bike runs really well with the red needle on the 4th clip, a 42 pilot, 180 MJ, 60 LJ, and the fuel screw 1-7/8 turns. The pilot is stock, and the main jet is stock.

Greg.

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