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Discussion Starter #1
Im debating between building the 660 motor to a 720 stroker or doing an R6 engine swap. I would appreciate if i could get some pros and cons of each.
 

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720
Pros: Likely cheaper, less involved and faster/easier to do, lots of support from others that have done the same, proven reliability and power.
Cons: not as much power as an R6 motor, requires more than just the crank and piston to make the most of it (headwork, cam/springs/valves, possibly carbs)

R6
Pros: more power, engine should be reliable if it's in good shape and you leave it relatively stock
Cons: very involved and a lot of custom machine work and frame modifications to be done, not much support, not as much power as a good liter engine like the R1
 

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i wish i knew the pros and cons of each cuz i would like to know, I always kinda liked the original engine that was built better then engine swap, im a little bias cuz i really want to put a 720 on mine

thanks MD
 

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Discussion Starter #5
I have all the necessary equipment and mechanical knowledge to do the swap. i Just wanna go with the one that will be best and most reliable overall.
 

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I guess I have to ask what you want to do with it. If you want the most reliable way to make triple digit hp then yes a street bike swap is the better way to go. But if you're happy with 60-75 hp I would build up what you have.

The R1 motor doesn't weigh that much more, there was a recent thread in the 700 section about a guy contemplating a turbo 700R or an R6 motor and that point was discussed, the motors aren't that different (R6 vs R1) in terms of weight because you're looking at the same basic design (4cyl).

I wouldn't go to the mx track with a street bike conversion, and I can say from what I've seen personally they are quite a hand full on the trails (300ex with a ninja motor) though certainly the chassis, suspension, and setup matters quite a bit in such applications.

If you're building a dune or drag bike, then the streetbike conversion starts making more sense.
 

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Discussion Starter #7
I do lots of mild high speed trail rides with built trx's, banshees and 2 stroke dirt bikes.
 

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Discussion Starter #8
Im tired of falling behind and would like to get the edge on them. Ive improved my handling quite a bit and done several tasteful mods.


CRJ 3 1/2 front lowering kit, Flipped rear link, Moose Front bumper and rear grab bar, DG nerf bars, Motion pro twist throttle, G force + 3 1/2 rear hubs, Big gun CDI, Dynojet stage ll kit, [email protected] filter, no air airbox lid, yoshi slip on, pirelli race rails, and last but not least a 530 chain
 

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well man the all different machines, not so sure on the trx stuff but shees and dirt bikes i love, you should beat the banshees out of the whole but when it comes to top end bye bye so long, if the dirt bikes are 250 2 strokes you are in a world of hurt cuz the move all the way around..i still am trying to find a happy medium where i can catch my banshee in 1/4 to 1/2 mile drags, right now im not close
 

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I think you'd find a streetbike conversion a handful in the trails, The increased weight, COG change, chassis differences (loss of frame and rear sprocket ground clearance along with power delivery would be a concern to me but certainly I will defer to anyone else with experience and insight to add on this. I haven't logged many hours on these types of machines, least of all in the trails.

If it were me in that situation I'd go for the 720 build, probably looking at around 2k for a stock carb build which would put you around the 65hp mark. For reference, a stock 660 makes 35hp, you are probably making around 40hp with your setup.
 

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There is no definitive write up on it, but there are quite a few that are a good reference. I will see if I can dig some up with a search and post a few links later this evening.
 

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The vito's kit is a good one. It uses the Barker/Vito +4mm crank that uses the stock wristpin location meaning you can use any off the shelf piston with it. There are some who aren't big fans of the included JE piston (I'm still weary of them) but I haven't seen many JE failures in the last few years and none from those using the 10.75 piston included with this kit.

Pair that kit with a solid port job and you'll be in pretty good shape.

Other recommended but not required upgrades include a new clutch kit w/ stiffer springs (GYTR is the preferred option), billet clutch basket, and aftermarket valves (probably stock size for this application and most will recommend ferrea brand).
 

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Discussion Starter #16
What about carb setup? Ive looked into the edelbrock single.? Dont have alot of knowledge in the carb area.
 

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Edelbrock single isn't big enough to feed a build like this, it starts to strain with anything larger than a stage 1 type camshaft. You need a 48mm or larger single, the Edelbrock is a 42mm oval bore.

The carb of choice is the Keihin FCR in dual 35mm or 39mm sizes. Whether or not you step up to the 39 depends on your port job and your plans for the future. If you've got enough flow, you can run the 39's but the 35's flow quite a bit and are a bit more responsive off idle.

Prices range from 800-1200 depending on where you buy them, how they are set up, and whether you buy the intake with them or separately or not at all.
 

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Discussion Starter #18
All said and done what kinda power could i make with the 720 kit 39 FCRS with intake and ported head? I dont mind to spend the money if its doin it right.
 
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