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Discussion Starter #1
One of my buddies raptor 660 is dramatically slower than it should be. He has the same fmf exhaust set up and vito's jet kit as me and i can just walk all over him. He is even getting beat by suzuki ltr 400 with guys twice his size on them. What could cause this?
 

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Many things.... Rider, Jetting, in need of motor work. Will need more details then what you said to even get a start at why its slower.
 

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Master of the Electron
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Rings worn out or bad jetting or one of a hundred different things - without a lot more information, the issue is wide open.
 

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I am unique
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One of my buddies raptor 660 is dramatically slower than it should be. He has the same fmf exhaust set up and vito's jet kit as me and i can just walk all over him. He is even getting beat by suzuki ltr 400 with guys twice his size on them. What could cause this?
Dirty air filter...........:)
 

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Discussion Starter #5
Well its a 2003 raptor 660 and it has the vito's jet kit installed in it 155 and 160 main jets, 25 pilot jets with the fuel screws about 2 1/2 turns out. It has an fmf powerbomb and titanium muffler with an aftermarket air filter and no lid.
 

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Have you checked the compression? If it is in need of rings and a bore or hone, it will lose a lot of power.
 

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Master of the Electron
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Main jets are a bit small, and it should have aftermarket needles but this should be noticable if bikes running too lean.
 

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Discussion Starter #8
They are aftermarket needles and the spark plugs looks about right, a nice brownish. We'll have to do a compression test and see what that shows.
 

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Master of the Electron
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That would be my next step too.
 

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well as i just found out.....check to make sure that the screw on the back of the thumb throttle isnt screwed in....this will limit the throttle from going wide open....just had this problem on my raptor and happened apon it by accident....i got tons more power and speed now.....just a thought
 
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