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Discussion Starter · #1 ·
i want to build a 727, and i know a 5 mm bore will achieve such displacement but i would rather stoke it. would a 4mm stroke and a 1mm bore make this happen or will that send my numbers off?
 

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Discussion Starter · #3 ·
Awesome, thanks Mike. any pros and cons you might be able to dig up as well?
 

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Both methods of getting over 719cc require splitting the cases, with the stroker it's to install the crank and with the bore it's to clearance the cases for the oversized sleeve.

The stroker will put a little more pressure on the cylinder wall because of the rod/stroke ratio, but have proven thus far to be pretty reliable a build and last for a reasonable amount of time. The smaller bore will handle higher compressions a bit better due to the increased size of the head gasket sealing area, but neither should be an issue on pump gas. The stroker also means you're getting a displacement and power bump for your new crank, where as with the bore only you'd have to buy a new rod anyway to replace the OEM, or a whole new crank, to safeguard against the weak link that is the OEM con rod. If you buy the barker crank you have a lot of piston options, downfall of the hotrods being the limited number of shelf pistons that have the requisite 2mm offset wristpin location.

Advantages to bore only, well not a whole lot. You can end up with a larger combustion area and can make better use of oversized valves if you have them and the porting and carbs to push them. These builds can run a bit smoother if the piston weight is right and there's a good number of shelf pistons around for this size, certainly more options than a hotrods 719 kit.

I usually tell people if they've gotten to this juncture and still run a stock rod that they should look into the stroker setup. I personally went with an all bore 727, but I already had a hotrods stock stroke replacement crank in my quad when my 100mm bore finally needed a rebuild. If I wouldn't have had that crank, I'd probably have a 719 right now....and I'd be wanting a 762 ;)
 

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Discussion Starter · #5 ·
very good information. i primarily ride trails as you can tell by my plus 4 rear sprocket (great choice by the way) but i don't mind the occasional airtime that jumps and tracks have to offer. the purpose of this build isn't to soak the machine with as much power as possible like many people have visions of, i want a beast of a trail quad and was wondering b/c you have more knowledge on the subject then myself, what i would need to see maybe 65+ horse but still maintain reliability. i know my body will be soar with all the extra power but its not anything i wont get used too. so what numbers do you see in your eyes that would produce such a machine?
 

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Remember there is replacement for displacement :D On these quads, figuring you're on a budget, you would make more power out of head work, cams, carbs, compression etc. Just because the engine is bigger, without the supporting mods they aren't gonna be up to their potential. JMO. I don't know how many times I've seen 800+cc Raptors get beat by less than 700cc's
 

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Sounds like you want some torque and solid midrange, in which case I'd send you down the path of the 719 with an 11:1 or lower compression piston to keep you on pump gas. A good trail port with proper jetting on the stock carbs and an open airbox with preferably a clamp on single or dual filter kit. Might be tough debating a stage 2 or 3 hotcam...I for one certainly feel the extra power on top with the stage 3 but at the same time I know I've left some power on the bottom end. If your trails are open and you're running 3rd gear and higher all the time go with the stage 3. If you're putting around a lot and need power off idle I'd be tempted by the stage 2. That said, I ran a megacycle x4 in the trails with stock displacement and with the right porting and carbs I had great power down low, so perhaps the stage 3 would be a good go between. I like the megacycle cams as well, the x3 is a good cam for this type of build. The next step would be a set of 35mm fcrs to pair with the head but you can make over 60hp on the stock carbs without going crazy with the porting and cam, I've seen over 65 with them and then some when you do up the ante on the porting and valve train.
 

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I didn't notice much if any difference between the X4 and stage 3 hotcam on my 720, and my builder says they're almost identical on the dyno from the 720's he's built. I'd personally go with a stage 3 cam for the simple price difference.

I've also heard the X4 can be a bit tough on your rocker pads in comparison, though I can't really comfirm this, I didn't run it long enough to see much in the way of wear.

Like MD stated above with his build, I didn't really notice a lack of power down low either, and that's where I really need it for how I ride. I think a 719 with a good port makes MORE than enough power down low, and to run a stage 2 (I did for a short period) you're really limiting it up top. I know quite a few times I got frustrated with that cam limiting my build. The stage 3 and X4 performed much better IMO.
 

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Discussion Starter · #10 ·
what is the meaning of this???? ^
 

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Discussion Starter · #12 ·
learn i will raptor master hahah
 

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Discussion Starter · #14 ·
i know what it is willy, just never saw or even thought of one. i cant find a photo though =/
 
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