Oil Pump Notes
As far as I can tell ALL the 3 hole pumps are
internally EXACTLY the same.
What makes them pump different is that the gearing to the crankshaft is different. Kaw didn't make 5 (or whatever) different pumps ... only different gear sets for different displacements. Crabby and I proved this. SO ... putting a different pump on a bike does not necessarily mean you are pumping a different amount of oil.
The larger the engine ... the faster Kaw spun them ... that's all.
That's why I was asking Patrick about the throttle plate. I "think" those were slightly different in diameter, but I may be wrong ... which would also change (slightly) the amount of oil being pumped.
I tested a S2 and a H1 pump and ... at the same speed with the same throttle plate ... they pumped the EXACT same amount of oil.
What I don’t know is the diameter of the cable cam on
a H2 compared to the cable cam on the H1 …
If the H1 has a larger cable cam, then you are using less oil. Some measurements would verify this.
OK … I went back to some of my notes from 2 years ago.
Here is what I found:
The eccentric in the 3 hole pumps I have taken apart have exactly the same “throw” of .118” which means that the pumps piston travel is the same … OR … the output potential is the same.
Bike Crank Pump Final
Model Gear Gear Ratio
H2 7 18 2.57
H1 7 18 2.57
S3 11 32 2.91
S2 11 32 2.91
So … the H1 and the H2 pumps rotate at the same speed. Which generates the next question, does that mean they deliver the same amount of oil to both the 500 and the 750 ???
Well, the only way they could change the oil delivery is to change the diameter of the cable cam.
The cable cam on the "S" and "H" series are different also. The "S" series “pulling radius“ is larger.
And they also pull counter clockwise instead of clockwise ... which doesn't change anything as far as output.
All the “S” series pumps rotate at the same speed (you can prove this to yourself by looking up the gears in the parts list … I did !!!)