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Need some tech advice on upgrades I just installed.

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I have a 06 YZF250 and I just installed an FMF 4.1 exhaust system (megabomb header and muffler), a Power Now valve and a Boyesen QuickShot accelerator pump cover. Everything else including jetting is stock. Do I need to do any jetting adjustments to tune this thing in. When I started the bike and let it warm up, it still has that bogg when you wick the throttle from an idle. I know from the factory these bikes do this, but after the upgrades, shouldnt this go away or is this something that all 4-strokes will do even after modding?

Thank you for any advice you all may have.

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I would try getting the correct jetting installed, FMF should have jetting specs for you bike and after you have jetted it properly and still have a bog, I would either install a smaller leak jet or do the complete redbeard AP mod. -download the pdf.

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Sorry to say, but you wasted $80 on that quickshot, you can cure bog for $10 with a simple little jet called a leak jet, the factory puts one in that is way to lean, you need to get a richer one in the #40-#50 range and return that quickshot.

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Sorry to say, but you wasted $80 on that quickshot, you can cure bog for $10 with a simple little jet called a leak jet, the factory puts one in that is way to lean, you need to get a richer one in the #40-#50 range and return that quickshot.

I was afraid to hear that about the Quickshot. My boss has me work on his boy's 2 bikes in the evening and he is really green when it comes to knowing about motocross and maintaining the bikes. He listens to everyone at the local tracks and they say get this and get that, and he buys the stuff without really checking it out or checking with me first. So, I just put the stuff on and try to make it work (and make him happy) the way he wants it to. I know what he wants.... a bike with no bogg when you hit the throttle from idle , hard hitting low and rips all the way thru to the topend. I will mention to him about the leak jet. Not sure I want to try the AP mod though as it isnt my bike. Maybe on my 01 though if its possible!!

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Forget the leak jet leave it stock. O ring the AP linkage, its easy and it works.

PM me for any details.

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I installed a #45 leak jet on my '06 WR250 (same engine as your YZF) along with a JD jetting kit and that worked wonders.

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Forget the leak jet leave it stock. O ring the AP linkage, its easy and it works.

PM me for any details.

And so does the correct leak jet and NOT "O"-ringing the AP linkage.

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And so does the correct leak jet and NOT "O"-ringing the AP linkage.

I tried it both ways and the O ring not only had the best response and by far the easiest to do, and it didnt over richen it like most leak jet guesses.

Yamaha got the leak jet right once the linkage is corrected, its perfect.

I dont recomend the o ring if you have already installed a smaller leak jet. It will be way to rich, the motor will feel dull and lack crispness.

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I tried it both ways and the O ring not only had the best response and by far the easiest to do, and it didnt over richen it like most leak jet guesses.

Yamaha got the leak jet right once the linkage is corrected, its perfect.

I dont recomend the o ring if you have already installed a smaller leak jet. It will be way to rich, the motor will feel dull and lack crispness.

Well I havent done anything yet, just weighing the options at the moment.

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Do yourself a hugh favor an order the JD Jet kit from this site. Your bog will be gone. This is what I did with my 06 YZF 250, along with a Megabomb header, Stage 1 HotCams. Completely different bike without the bog.

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I also have the Boysen Quickshot. There is no way that it is a bad investment. Get yourself the Fuel Screw while you are at it.

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Note that it may bog on the stand, but you should only conclude your jetting with a load on the motor.

My bike bogs when on the stand, but with a load it is purfect. This doesn't mean my jetting is off......

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Note that it may bog on the stand, but you should only conclude your jetting with a load on the motor.

My bike bogs when on the stand, but with a load it is purfect. This doesn't mean my jetting is off......

Some truth in that. Like jetting a 2 smoke, if you over richen, throttle response and overall performance will suffer. A very slight bog on the stand is OK on a 4 stroke.

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