Big Bore Kit Horsepower rating

B Rad

B Rad

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Joined
Nov 19, 2007
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53
Location
Yorkville,Il
Does anybody have any idea how much horsepower these kits add to a stock motor??

I know the stock rating is 140. Just trying to get some calculations together for a different application I am working on.

Thanks
 

780 bigbore with stock bored carbs from 160-175hp trailable on pump gas depending on who's kit.
 
i dont think yoo need to bore the carbs to acheive these hp, maybe more can be had by boring them tho, how big can you bore them up to? and i wonder for the time and money it will cost to get them bored if mach z carbs are a better investment.
 
Ok, if this thing has 38mm flat sides with a 780 kit plus porting, v-force reeds and bender race pipes, I should be over that number above?? Correct
 
how mutch power can be gained from boring out the stock carbs and how to what size can you safely bore them? im going 780 very soon thats why, dont want to go the mach z side tho, i want to keep the stock look, jsut wondering what gain there is to be had from boring the carbs out. Stock pipes also
 
I wonder how much more power the 38mm carbs would make over a set of bored 35mm carbs, from hauck or someone. I have a 760 kit on a sxr non pv motor and it pulls pretty dame hard. I raced a attack over the weekend a half dozen times and won every time by almost a sled length or a little more. I'm tring to run the jetting alittle better.
 
must be a good running attack or you have some big gain to be made yet!! Our ported 700 NPV with CPR pipes would run down the average attack.. Would think the 760 would have us by at least 10-12HP or more..
 
Stock pipes, carbs, mild cylinder porting, and no case porting, the 780's are good for about 160-162 honest hp. The 38's will bring you up closer to 168 ish. Do some case porting, and some decent cylinder porting and you could be looking at 175, which is about the limit with stock pipes.
 
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