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Right now my raptor is bone stock but this winter i was thinking of doing some mild modifications. I heard that a 102mm bore could be done on stock sleve is that true, and how reliable would that be if i just trail ride most of the time, and the rest of the tome just show up honda's thanks.
 

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it is very true. but if your already fast, why do it? if all you do is trail ride you should spend your money else were. My friend had it on his and he loved it and all we did pretty much is trail ride. He did have more torque, but i didn't see much a of a benifit for trail riding. I have a stock internal raptor and i could keep up with him no problems in the trails. if you do alot of hill climbing, i could see were that benifited him, but i could go through the same hills on my stocker. Honestly, i'd spend my money else were for right now if all you do is trail ride, and your already showing everyone up. buy Like a full exhaust system...new shocks...extended rear axle...tires...different sprockets...ect. But if you feel the need for speed go for it, it's a relatively cheap upgrade for the power gains.
 

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most of your power from upgrading to a 102mm is going to come from increased compression. get a 11:1 high comp piston - run on premium pump gas. you will only see 1-2hp gain from just raising the displacement and 11:1 is reliable
 

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What mods do you have so far? If your quad is bone stock, I would recommend several things before tearing into the engine.

The basics being:

12t Front Sprocket
YFZ450 Front Shocks
Full Exhaust
Pro-Flo Kit
Clear Tube method and jetting
Extended swingarm (can do this cheap by modding the stocker)
Wider Rear Axle or Spacers
Good Tires (I like Razrs)
A-Arms
Pro Design shifter lever
Case Saver
Banshee chain guide
Skids
 

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cstande88 said:
Right now my raptor is bone stock but this winter i was thinking of doing some mild modifications. I heard that a 102mm bore could be done on stock sleve is that true, and how reliable would that be if i just trail ride most of the time, and the rest of the tome just show up honda's thanks.
My recommendation would be to save up for a cam and some port work, so you can do it all at once. The gain from just an 11.1 piston(stock bore or 686) will be minimal without the cam and porting.
 

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Rull of thumb you will gain at least 3% power for every 1 point of compression increase if all else stays the same so going up in cc will also gain power as well. Yamaha thought it to be a good idea for steppin up to the 686. I am 103mm(700cc) and 11:1 and I love it, wouldnt do anything differently if I had to do it all over again parts wise.
 

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VelociRaptor said:
Yeah, kinda tired of going through the spill of tellin em its not a true 700cc bike stock, its a 686- then tell em its 1mm over which makes it a true 700cc bike. ::)
Trust me, Polaris Ute owners feel your pain. The 800 is a 760... :crazy:
 
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