1991 650SX: 180 PSI of compression right and a couple ?'s - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

1991650SX · 06-23-2010, 08:39 PM

I just picked up a 1991 Kawasaki 650 SX ski. It appears totally stock, and when i did a compression test it showed exactly 180 psi on both cylinders. So I know its a strong motor, but were the heads shaved? The heads appear stock, it says Kawasaki. The guy I bought it from was playing with the case drain on it, but at the time I didnt know what it was because im totally new to stand ups. Is it closed when it is pushed down? I dont really trust the oil injection system, I prefer to premix. What is the best way to block it off? And what oil do most of you run? Ill probably just mix supertech at 32:1, but I love how klotz smells, if you have smelled it, you know. Also, what would be a good carb to run on this motor? The small single carb on it right now is holding it back for shure. Are these skis hard to jet? I am used to 2 stroke race bikes and sleds, which can require jetting changes for 20-30 degrees F or a couple thousand feet elevation change. Will it be hard to jet for maybe a pipe and air cleaner? For those of you that help answer my questions, thanks much.

Josh

prickofmisery · 06-28-2010, 02:40 AM

Quote:

Originally Posted by 1991650SX

I just picked up a 1991 Kawasaki 650 SX ski. It appears totally stock, and when i did a compression test it showed exactly 180 psi on both cylinders. So I know its a strong motor, but were the heads shaved? The heads appear stock, it says Kawasaki. The guy I bought it from was playing with the case drain on it, but at the time I didnt know what it was because im totally new to stand ups. Is it closed when it is pushed down? I dont really trust the oil injection system, I prefer to premix. What is the best way to block it off? And what oil do most of you run? Ill probably just mix supertech at 32:1, but I love how klotz smells, if you have smelled it, you know. Also, what would be a good carb to run on this motor? The small single carb on it right now is holding it back for shure. Are these skis hard to jet? I am used to 2 stroke race bikes and sleds, which can require jetting changes for 20-30 degrees F or a couple thousand feet elevation change. Will it be hard to jet for maybe a pipe and air cleaner? For those of you that help answer my questions, thanks much.

Josh

Josh when you dump the oil injection also 86 the crankcase drain, they are problematic and cause a lean condition as they are prone to failure resulting in engine issues. Just remove the oil takn and pump. Install a vacuum cap on the manifold injection line fitting and install the blockoff plate on the flywheel cover where the pump was removed. Same with the crankcase drain. Remove it and install a block off plate.

I have these parts if you are interested, as well as an aftermarket stinger pipe which is longer as well as many other items OEM and performance wise.

32:1 is a bit rich, I run mine at 40:1. I like to run Maxima SuperM, its fair priced for a very clean burning quality oil. Your 1991 should have a Keihin 38mm on it which is a good carb (much better than the prior years with a tiny 28mm). OEM spec for compression is 150psi +/-, so it appears that the head has been milled. Rejetting is simple.
Jason...