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i have a 07 yfz450 with an intake and exaust on it. The quad has great torque in the bottom end but when it gets to the top end it feels like it has very little to none. I also have bone stock 08 yfz450 and it will beat my 07 in a drag race. The gearing is also the same but for ome reason you have to shift the 07 quicker My 07 yfz that im having the problems with does bog when u give it full throttle instantly to if you hold it it will die im not sure if thats a jetting or not. i also have a motorcross track wich has a lot of sand and I could be in a 5th gear and give it full throttle and it wont bog even if i should be in 3rd gear. The guy i bought it from said the motor is stock but it has high compression and thats why i run it on race gas. So could anyone help me out thank you!
 

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if the motor is stock it does not have high compression or need race gas. it really does not even need super but that is the only way to get non ethanol fuel. as to the answer to your question. your torque will always fall off at wot. as to why it feels different , could be lots of things. are your sure its geared the same, are the tires exactly the same, does the machine have the same number of hours, is the clutch on the 07 slipping. if it is truly apples to apples. anything that has that fcr carb will have a bog unless the zip tie mod is done or you add a boyeson quick shot its just how they are. jetting and needle settings play a role in top end speed (are the 2 machines jetted the same) my guess is the 07 was not rejetted when the pipe and intake were added and it is lean in the main circuit. what color is the plug?. other options are it may need a valve adjustment or it could need a top end. stop with the race gas it is likely hurting your top end performance. not to be a dick but you sound like you dont have a lot of mechanical experience or a solid grasp on jetting. so my suggestion would be to put a jd jet kit in it. just follow the instructions for your elevation and mods and you will be good to go. i would also add and flex air mix screw to make dialing in the pilot easier
.https://www.ebay.com/itm/JD-Jetting-Jet-Kit-High-Performance-Yamaha-YFZ-450-YFZ450-ATV-04-05-06-07-08-NEW/361291754075?hash=item541eaaaa5b:g:baoAAOSwoudW4MBJ
i have built and tuned a bunch of these. every thing from bone stock to 70 hp bigbore strokers and i think these 2 things will go a long way to solving your problem. just an fyi 1 post is good there are only a few guys on here right now helping and we will get you an answer as fast as we can. extra posts just slow us down having to read the same post over and over
 

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Are you wearing gloves?i know you cant feel shit after 10 min of riding that vibrating junk for very long..
 
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