HELLOOOO AND HELP PLEASE LMAO

[LIDUNO]

I've had a few fl250's so I recognize the model, if you do a google image search, I'm sure you will recognize it too.

Like Mac mentioned above, that engine will need a good cooling system.

As far as putting a sport bike engine in it, with no rear suspension, I wouldn't recommend it. To be honest, the stock 250 2 stroke was fast enough to really beat the hell out of your back..lol

[K-fab]

Correct its a js 550 engine . I have a electric water pumo I was going to use and a small motorcycle radiator ..got it for basically 200 $ in trade and figured why not .. Would putting in a used mortorcyle engine and drive terrain make more sense, have a buddy with gsxr 600 that he said I could have 500$ needs carb and idk what else ,or would a used snowmobile engine be better bexause of the cvt?

Two things about using a Jet Ski engine that are going to be problematic (although, it looks as if who ever did the buggy may have worked their way around the issues):

1) Drive off the engine. The JS uses thread on couplers with a rubber piece as a drive between the two. I don't know of any CVT clutches that would fit on the end of the shaft. They're all tapered. But I see in the pix that who ever did it managed to adapt one so bravo on that.

B) Cooling. The JS uses a 3/8" line that is pressure fed from the pump. It goes into the jug (argh, can't recall the input - back of the engine, on the cylinders or on the exhaust manifold? - I had modded skis so I'm not memory familiar with that beast of a cast exhaust pipe). The water circulates through the cylinders, out of the head (front) and then through the exhaust system's header. From there it went to a water box (bypassing the expansion chamber) and then finally on out through the exhaust.

You're going to need to have a much larger water flowing ability over stock 3/8 nipple. That means opening up to at least 3/4" -1" (IMO) on both the intake and output of the system.

I'd think if you can get enough water flow and have a decent sized radiator - anything 500cc or above - especially four stroke based, as they run hotter than two smokes) you'll do just fine.

The 86 and later (up until the SX reed intake setup) 550 engine makes 46 hp if memory serves. With some porting and some head work you can get a very reliable 60 hp outta that power plant. We used to deck the heads so that we had 165 psi (still pump gas range) compression and widen the exhaust ports a BUNCH - they were almost D shaped when done, very wide at the top - wanna say 2mm each side of removal. You'll start loosing ring life, though as they don't like being slammed back into the piston groove on the way up by the wide top of the port. Don't know if your engine has a bridge in the center of the port or not - like I mentioned, all my stuff was aftermarket and nothing stock about it. If it has the bridged exhaust port, you'll have longer ring/piston life.

From what I see you have a good start - may as well take it as far as you can before you dive into throwing in a completely different power system, like a bike.

Hand me any 440/550 Kawasaki Jet Ski fully disassembled, nuts/bolts everything in a box, unmarked and I'll give you back a running ski in under 6 hours. They're like CRF50s to me - can rebuild in my sleep blindfolded. Too many hours under the hood of those darned things.

[K-fab]

Sumthing along the lines of this guy:

PJS exhaust on that thing! WOO HOOO!!!!
My old PJS reed induction cylinder 550 was making close to 80 hp and was a legit 49mph ski. They're exceptionally rare now. PJS and WestCoast probably made the best stuff in the JS world back in the day.