Suzuki 2 Strokes

I bought a GT750 engine some years ago and now I noticed the oil pump that is installed has an arm with "341" engraved, I was told this is from a GT550.
The oilpump itself looks identical to my GT750 pumps, except for the lever.



Are the oil pumps for GT550 and GT750 the same?

In a SUZUKI Bulletin, the output of the oil pumps for a GT550 and GT750 is specified differently at same RPM, both with lever fully closed and fully open, does this indicate the pump is different or is it just the lever making the difference in capacity?

The pump shown in the pic is mine. I have adjusted it so that the upper dot aligns at throttle closed and the lower dot at fully open.

The GT380, GT550 & GT750 pumps look the same.
Part #s for the 1975 pumps are:
GT380: 16100-33100
GT550: 16100-34101
GT750: 16100-31202

Suzuki doesn’t stamp the “16100” on the part because that just indicates its a pump & you can see that.
My spare GT750 pump has “312” stamped on the arm.
My GT380 project bike pump has “331” stamped on the arm.

Your “341” indicates its a GT550 pump.

How you adjust the pump depends on which type of carbs you have.
Do you have throttle cables going to each carb, or do you have a bank of carbs?

Look here for help and information
http://www.pinkpossum.com/GT750/Oilpump.htm" onclick="window.open(this.href);return false;

Hi,
Now I'm confused. After reading the parts list supplied by jabcb on oil pumps I decided to check the one on my second 380 engine I'm rebuilding. I bought a pump off ebay advertised as a GT380 pump but on checking the number stamped on the arm it reads 330. So what's this one off ? Any ideas.
Regards,
Glyn.

1972 GT380 oil pump is part # 16000-33001.

“330” is for an early GT380 that has a throttle cable going to each carb.
“331” is for a later GT380 with the push/pull throttle cables.

The oil pump setting procedure depends on which type of carbs you have.
The alignment marks on the arm depends on the procedure, so the part #s are different.

If Suzuki specifies different output, then the pumps are different.

My guess is that the plungers (pistons) and rotor (valve body) are the same and that the face cam in the top cover probably has slightly less "lift" than the 750 pump.

If you strip the pump, it would be useful to measure piston diameter and cam lift to be sure.

jabcb wrote:1972 GT380 oil pump is part # 16000-33001.

“330” is for an early GT380 that has a throttle cable going to each carb.
“331” is for a later GT380 with the push/pull throttle cables.

The oil pump setting procedure depends on which type of carbs you have.
The alignment marks on the arm depends on the procedure, so the part #s are different.

Hi jabcb,
That's a shame as I've just rebuilt the pump with new seals & top gasket and it seems to be working fine. Is it not a good idea then to use the pump on a 75 GT380M motor with the gang carbs. Or could I just change the operating arm with one stamped with 331.
Regards,
Glyn.

Glyn.G wrote:

jabcb wrote:1972 GT380 oil pump is part # 16000-33001.

“330” is for an early GT380 that has a throttle cable going to each carb.
“331” is for a later GT380 with the push/pull throttle cables.

The oil pump setting procedure depends on which type of carbs you have.
The alignment marks on the arm depends on the procedure, so the part #s are different.

Hi jabcb,
That's a shame as I've just rebuilt the pump with new seals & top gasket and it seems to be working fine. Is it not a good idea then to use the pump on a 75 GT380M motor with the gang carbs. Or could I just change the operating arm with one stamped with 331.
Regards,
Glyn.

I’ve never seen anything about Suzuki changing the oil flow rates on the pumps for the triples.
I would expect that you just need to switch out the arms.

If the arm is installed 180 degrees out, then you get max flow rate at idle. So its advisable to mark the shaft orientation with a dot of paint before removing the arm.

Alternatively, see if you can find good pics of the early & late arms. You may be able to account for the different markings without swapping the arm out.