motorcycle engine minibuggy.

[Engineer]

I have ridden a 250 ninja and would not suggest using that motor.  The power is very peaky, and it would be hard to take off with the cart.  The industrial would have way more useable power with the centrifigal clutch.  Much easier to install as well.   

[SPEC]

I think all would be suprised at the speed and grunt power that can be achieved out of an Industrial motor with a torq o verter drive...Sled clutching, and the right gearing

[fabr]

Compared to what?  I grew up racing karts with 5hp briggs engines and on some tracks they could get up to 70mph. 

You just have to be realistic about the whole thing.  With no suspension you are going to be limited on how fast you can go on rough terrain.  So no reason for tons of HP.  If you want a badass toy, it's going to cost you $$$.  IF you want something simple to get you started then stick to the plans.

Figure out what type of riding you want to do and what your budget and skills are. Then go from there.

I gotta agree with that.

[Boostinjdm]

  The industrial would have way more useable power with the centrifigal clutch.

I seriously hope you meant to say Torque converter.  Centrifugal clutches are great for racing.  They suck ass for playing.

[Wyattboche]

What are you planing on using the buggy for? Just around the yard, or in the woods, or

[samsonjohn]

around the yards and the woods mostly just to screw around on.

[Snoopy]

PLEASE do yourself a favor and check into using a quad or 4 wheeler as an engine donor.   It comes with reverse, you can use an air cooled one for that size buggy and the power would really suprise you in something that small.
A 300 ex is an outstanding little quad motor and you should be able to find a complete quad for 1000 to 1500, you could use the front end, the motor and electrics and sell off some of the rest on flea bay to make most of your money back.
And you will have a hard time killing that motor. We use them here in smaller buggies like the one your considering. It's a proven formula that works everytime.     

Here's a link to the video section of this site with a 300 ex in a chinese type mini buggy. small, fun, CHEAP and dead reliable little engine.          not to mention you can find smaller used 4 wheelers of just about all types on craigslist. 

http://www.dtsfab.com/index/index.php?topic=1465.0

If it's your first build I would really recomend keeping it as simple as possible, and 600 streetbikes motors are just about anything but simple.   Best of Luck, snoopy