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Discussion Starter · #1 ·
I want to do a big bore kit on my 05 660, but i dont know which one i should do, the 686 or the 720 or the 727? I want it to outrun my friends 08 Polaris Outlaw 525. Any suggestions?
 

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686 will be the cheapest, it's just a bore, hone and piston. The 720 will require a stroker crank, the 727 will require splitting the cases and you should replace the crank while you're in there anyway.

A good port job and a more aggressive camshaft would make the most of any bore increase.
 

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Discussion Starter · #3 ·
686 will be the cheapest, it's just a bore, hone and piston. The 720 will require a stroker crank, the 727 will require splitting the cases and you should replace the crank while you're in there anyway.

A good port job and a more aggressive camshaft would make the most of any bore increase.
sweet thanx man! Do you think with the 686 it will outrun the Polaris Outlaw 525?
 

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terrain, riders, and what's done to the polaris will have a lot to do with it, but if you had a port job, a cam and a higher compression 102mm piston in there I think you'd have a very good shot at beating the polaris provided it's a bolt on bike or less.
 

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I don't think just putting on the big bore will make it WAY faster. It is the porting that makes there raptors scream assuming you already have the "Big 3" then I would look at porting and a Higher compression piston but the list can go on of what you should do....;) And just a warning I have not found a Cure to the mod bug yet:eek: so be careful.
 

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At what point does someone need to start thinking about FCR's? In otherwords, at what point will the stock carbs be at there limits....
 

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You can always build it up and then when it feels like you top end is lacking pull the trigger on some FCR's. I ran a 720 with a open intake, Sparks exhaust, Stage 3 cam and P&P head on stock carbs and it was still a screamer. I have FCR's now but changed the whole head+porting+cam+FCR's out at the same time so I don't know how much just changing to FCR's does. From what I read on here though its a drastic change.
 

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I've seen a number of builds making low to mid 60 hp numbers on stock carbs. There are some mods you can do to them as well to push it a bit farther.

FCR's are great, but in some cases can double the parts cost of a build. It's all about how and where you want to spend that money. If you've got it then go for it, but it won't be crippled without them.
 

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Im also looking at the 686 kit.Right now im stock with a slip on,filter,and jetted.My plan was to have new guides and springs put in the head with a stage one cam,and a 11.5 to 1 wiseco 686 kit. Im looking for bottome end mostly and just want to know what i can anticipate from this type of setup?????
 

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A few years ago when I first competed in oval track racing I competed with a 660cc with HV porting, dual FCR 39mm carbs, White Bros exhaust with my own head pipes, carrillo rod, and of course the 3 plughead................
I didnt worry about any 686cc, or stroked 720s or 727 big bores. Some had dual exhaust and FCRs...........
 

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A few years ago when I first competed in oval track racing I competed with a 660cc with HV porting, dual FCR 39mm carbs, White Bros exhaust with my own head pipes, carrillo rod, and of course the 3 plughead................
I didnt worry about any 686cc, or stroked 720s or 727 big bores. Some had dual exhaust and FCRs...........[/

That doesnt tell me anything! The build I listed is around 1000 dollars. Maybe I should rephrase my qeustion, If you had a 1000 to spend on performance above my current add ons that are in my sig how would you spend it?
 

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A few years ago when I first competed in oval track racing I competed with a 660cc with HV porting, dual FCR 39mm carbs, White Bros exhaust with my own head pipes, carrillo rod, and of course the 3 plughead................
I didnt worry about any 686cc, or stroked 720s or 727 big bores. Some had dual exhaust and FCRs...........[/

That doesnt tell me anything! The build I listed is around 1000 dollars. Maybe I should rephrase my qeustion, If you had a 1000 to spend on performance above my current add ons that are in my sig how would you spend it?
'

You said you wanted to beat a Polaris Outlaw 525, you never mentioned any amount of money. I told you how I beat, ( in oval track racing), the engines you were considering to beat this Polaris, and the engine I used was a stock cc engine with the addons I mentioned................
 

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'

You said you wanted to be a Polaris Outlaw 525, you never mentioned any amount of money. I told you how I beat, ( in oval track racing), the engines you were considering to beat this Polaris, and the engine I used was a stock cc engine with the addons I mentioned................
mr Willykiller mr fsashemi high jacked mr parknastys thread.. Damn terrorist lol
 

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lol, i guess i did hijack
 

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Discussion Starter · #19 ·
A few years ago when I first competed in oval track racing I competed with a 660cc with HV porting, dual FCR 39mm carbs, White Bros exhaust with my own head pipes, carrillo rod, and of course the 3 plughead................
I didnt worry about any 686cc, or stroked 720s or 727 big bores. Some had dual exhaust and FCRs...........
With the 686 big bore kit, would you recommend a Hot Cam stage 3 and a Hot crank 4mm stroker crank?
 

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With the 686 big bore kit, would you recommend a Hot Cam stage 3 and a Hot crank 4mm stroker crank?
I have never used a stroker crank yet so I can't really comment on it and as far as a Hot cam stage 3, I have used them extensively along with the X4 cams, great power band, but again I have only used these cams with a 3 plughead..................
 
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