Kawasaki 4-Stroke Cylinder Identification

[grumpy_steven]

There are several different cylinders used on the Kawasaki 4-stroke motors. They all look similar, but there are differences that one might not readily notice.

I've seen ads for cylinders that indicate compatibility with different models, even though the parts are not interchangeable.

This thread will show some of the different cylinders and highlight the differences. These are cylinders that I've come across and may not be the complete catalog of the different cylinders. All of the sets of photos will be posted in the same order... exhaust side, intake side, top, bottom.

I'm pretty sure that the bore is the same on all of these parts. The bolt patterns are all identical. There is a height difference between the N/A motor cylinders and the S/C motor cylinders, with the cylinders from the N/A motor being slightly smaller. This is probably the reason for higher compression on the N/A motors.

Haven't worked on any of the newer N/A motors, but I'd have to guess the parts aren't much different.

Please refrain from posting comments in this thread, at least until the project is completed. It would be best if a reader didn't have to sort through posts to find the relevant posts. Also, it would be best if all of the pictures are on the first page, so a reader can easily compare them

[grumpy_steven]

STX-12F

Part #11005-3758 (2003-2007 STX-12F)

Height between mating surfaces: 3.44 inches

Overall height: 4.31 inches

[grumpy_steven]

STX-15F / Ultra LX

Part #11005-3761 (2004-2010 STX-15F, 2007-2008 Ultra LX)

Height between mating surfaces: 3.44 inches

Overall height: 4.31 inches

Difference from STX-12F: Deeper water jacket. Exhaust-side cooling water passage positioned lower.

[grumpy_steven]

Ultra 250 / Ultra 260

Part #11005-3766 (2007-2008 Ultra 250, 2009-2010 Ultra 260)

Height between mating surfaces: 3.7 inches

Overall height: 4.57 inches

Difference from STX-12F/ST-15F/Ultra LX: Height. Addition of bolt holes for supercharger. Crankcase ventilation passages go all the way through to the head.

[grumpy_steven]

Ultra 300

Part #11005-3770 (2011-2013 Ultra 300)

Height between mating surfaces: 3.7 inches

Overall height: 4.57 inches

Difference from Ultra 250/Ultra 260: Shallow water jacket. Elimination of cooling water passage on exhaust side. Elimination of bolt holes for crankcase breather. Supercharger stud/bolt holes in different position.

[grumpy_steven]

Ultra 310

Part #11005-0630 (2014-2019 Ultra 310)

Height between mating surfaces: 3.7 inches

Overall height: 4.57 inches

Difference from Ultra 300: Deeper water jacket. Addition of cooling water passage on the exhaust side and knock sensor port on the intake side.

[mwhc]

That's a knock sensor boss on the intake side of the 310 cylinder fyi

[smokeysevin]

One other difference on the 12f vs the 15f is the lenght of the lead in chamfer on the bottom of the cylinders. This is really important because it means you cannot use 12f cylinders on a 15f without pulling the piston skirt out of the bottom of the straight section of the bore.

Sean