oil pump colors

tz375 · Post by **tz375** » Mon Jul 20, 2009 5:20 pm

Err Dave,

I did, in a much earlier post in this thread but it may have been missed.

Thanks for the reminder though.

Suzukidave · Post by **Suzukidave** » Mon Jul 20, 2009 5:25 pm

oops .. sure enough

jkevinlilly · Post by **jkevinlilly** » Mon Jul 20, 2009 5:55 pm

I learn something new damn near every day on this forum.

Kevin

Coyote · Post by **Coyote** » Mon Jul 20, 2009 5:57 pm

Don't feel alone Kevin

Coyote · Post by **Coyote** » Mon Jul 20, 2009 6:37 pm

So when you start the motor and you hold the pump arm wide open, does the piston rise and fall faster? I know the pump is gear driven and that relation can't change. So what is the advantege of holding the pump arm open?? How does it know to pump more oil when the gear drive doesn't change? How does that work??

Suzukidave · Post by **Suzukidave** » Mon Jul 20, 2009 6:50 pm

http://www.3cyl.com/mraxl/gt/manuals/gt750man/sr44.htm

tz375 · Post by **tz375** » Mon Jul 20, 2009 11:37 pm

Good question Chris, and the answer is simple, but explaining it isn't.

The shaft at the bottom is part of a drum which contains the plungers which are the pump pistons. The way it pumps oil is that as the whole center drum rises, the small cylinders fill with oil and when it drops, that oil is pumped out though various drillings.

The arm at the top is ground like a cam so that it restricts how far the "drum" rises. At idle it can only move a few mm, but wide open the whole drum can rise much further. It is a variable stroke device.

If you are familiar with a swash plate hydraulic pump used for example in a jet engine fuel supply, it works more or less the same way. Rotary motion of the "drum" allows the pistons/plungers to rise and fall (reciprocating motion). The difference is that this pump uses a face cam in place of an angled swash plate.

In the link that Dave posted (thanks Dave), you can see that part 5 is different on the top left to top right. As it rotates that change in height causes the part to rise and fall (see the up and down arrows). The plungers are different lengths to get more oil to the barrels than the big ends.

Part 3 is the actuating arm and it restricts the stroke of the pump. If the bike stops when part 5 is at the top of it's stoke, and teh throttle is opened and then closed, teh actuating arm cannot close properly until the motor turns a few more revolutions. People think that it's sticking. but it's not really.

So a GT oil pump changes the stroke and therefore volume of oil pumped per revolution by changing the arm position. And the pump output is directly variable with engine speed. It's a clever design.

Coyote · Post by **Coyote** » Tue Jul 21, 2009 7:12 am

If I read the article correctly, more oil is provided to the cylinders than oil to the crank bearings. Does this mean when I fire up with this new red oil, the lines to the crank will change color at a slower rate than the 3 going to the cylinders?

tz375 · Post by **tz375** » Tue Jul 21, 2009 9:57 am

yes sir.

I'm not sure how easy it will be to see though. I tend to fire the bike up and take it around the block and when I get back all the lines are full of the new oil.

I don't have the figures for a 550. It's the 750 data I was quoting, but I would expect it to be similar.