75 GT550M Oil Pump Problem

[Syd]

I seem to have a major problem with the oil pump on my GT550M as after taking it for a 90 km ride the other day, I basically used 3/4 of the oil in the oil tank which obviously is not right. All of the oil lines are full so I am wondering if the pump internals have not been assembled correctly when I restored the bike and the pump is pumping to much oil.

I removed the top of the oil pump today as shown in the attached photo which shows the top as it came off. Can anyone tell me if the cut out in the shaft which is adjusted by the oil pump cable is in the correct position and does the rotor position in the pump body look correct? From a photo I received yesterday, it would appear that the top shaft cut out position is not correct on my oil pump.

Has anyone had this type of problem before and can help with some suggestions on how to inspect the pump and how to solve this problem?

[Harrymail]

Syd, see my reply on Kettle Clinic forum.

Paul

[Syd]

Thanks for your reply Paul which is very much appreciated with the photo you sent me. Just trying to spread the net for ideas as I am not 100% familiar with the workings and set up of these oil pumps and I would be interested in hearing from anyone who has had the exact same problem that I have to find the correct way to fix the problem. Cheers Ian

[jabcb]

Was the bike generating a lot of exhaust smoke? I would expect serious smoke signal generation if you burned that much oil so quickly.

The two stroke oil might just be leaking into the transmission. Check the transmission oil level. Drain the oil & measure how much you get.
The only oil pump repair part Suzuki sold is the oil seal between the pump & transmission.
https://www.partzilla.com/catalog/suzuk ... 0/oil-pump

Some info about the oil pump is here: https://www.oldjapanesebikes.com/GT750_ ... e/page-A57

Did you use a new correct-thickness top gasket?

Did you have the pump actuator arm off? It’s possible to install the arm 180 degrees out of the correct position — this produces maximum pump flow at idle.
The PO did this to a GT750 I bought. See this topic about it: viewtopic.php?f=2&t=11662&hilit=oil+pump&start=15
(Make sure to look at the end to see the pics.)

[Syd]

Thanks for the info Jacob and info on the GT750 oil pump which is very helpful

I have tried several times to attach a photo which loads on the page ok but shows up as an error (yellow triangle) under status which says " The image file you tried to attach is invalid" The photo jpeg is the right size at 340 KB. I have sent a message to the contact us on the website.

The photo shows the oil pump with the top off and I have not yet removed the lever and spring, however I will do this today. I am still running the bike in with 115 miles on the clock, therefore the max rpm on my recent ride was 3500 rpm. I'll also check the gearbox level as well. Paul (Harrymail) sent me a photo of his oil pump top ready to assemble and the cut out in the shaft is in a different position compared to my shaft, therefore I suspect this could be the problem.

I did strip the pump down during the restoration and cleaned the pump and reassembled with a new Suzuki gasket, therefore the arm & shaft could be in the wrong position. The bike right from the first start up gave out heaps and heaps of smoke, so I adjusted the mark on the lever down by 2-3mm which seemed to help slightly, however it was still very smokey which did not settle down on my 90 km ride the other day. If the shaft position is wrong, maybe this made matters worse?

[jabcb]

I think there were two different pump designs. So your pump internals might look a bit different that the pics.

Try the procedure in my topic to see if you can determine if you have the arm 180 degrees out.

[Syd]

Checked out the oil pump shaft setting and it was incorrect so have now changed this 180 degrees to the correct location and will give the bike a run tomorrow. Thanks for your help

[Harrymail]

Good luck, hope its now sorted.

Paul