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midrange hit

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okay so i have a 2006 Yamaha yz450f and first things first this thing is amazing. now, i have a full fmf titanium factory 4.1 exhaust with the megabomb header, jd jet kit with the thick o ring, iridium plug and the twin air proflow kit. the jetting specs are as follows:

Main:170

Pj: 48

Needle is the red needle from the kit on #5 clip

Fuel screw: about 1.25 out

Question is, i want the midrange to be more snappy it seems to be sluggish when around half throttle i feel like it should pull harder then it does. The top end is amazing and the bottom is alright too i wouldn't mind some more response when the throttle is snapped open though when rpms are lower and like from no throttle to a quick snap such as if you tried to hop over a log or something. i live in central Md so the altitude is not that high.

Any thoughts are really appreciated. Thanks Again

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okay thank you i will try that this weekend. you dont think that will lean it out too much do you?

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yeah i wanted to start out rich and see what happened i was running a 168 main and felt the the plug was too white. thank you for the advice

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You cannot read plugs with todays pump fuels. Een then, you must run/chop and pull the plugg immediately, very hard to do on a modern bike. That and a new plug must be used every time. You want to do it scientifically, use a wideband on a uncline timed set distance run.

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okay so i raised the needle clip to the forth position from the top and left everything else the same and i had alot of bog when throttle was opened quickly the midrange did feel a little better but i would rather have the softer hit midrange and not have as much bog. just a side note so far i am not impressed with the jd jet kit. maybe i just need to fine tune it some more. do you think that if i bring it to the third clip the bog would go away or get worse? also, if i go up to the third clip do you think that i should change anything else? i jave alot of different size jets laying around

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...and there in lies your problem. You do not set the needle to deal with a bog, you set it for steady state, undler load running. You adjust the A to deal with a bog. The problem is not the jet kit, it is the installer. Again, I explained it should be on the third clip, not the fourth or the fifth.

First, did you check/set the AP timing EXACTLY per the manual? Did you confirm you have a good squirt? Did you do the oring mod or put a stiffer AP spring in? What size leak jet are you running?

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okay ill try the third clip tomorrow and i will set the ap per manual and see what happens im not sure how its set up yet all i know for sure it that when i put the jet kit in and had the carb off i adjusted the screw so that there was no play in the linkage and i do have the thick o ring on the arm too.

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You do not just arbitrairaly turn the timing screw. There is a very specific method to follow in the book. It is 99% accurate. Some need slight tweaking after that is done by riding small adjustment, riding.

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