Oil Pump lines and Engine Casing Holes Question

[sparkmark]

Hey guys,

I recently picked up a GT750 L here in Sunny SA. After a ride I noticed that the RH exhaust was fairly dry compared to the LH and C exhausts. So being that its an unknown bike, I decided to check the whole oiling system.

First thing that I picked up, was that the oil canister was slightly sucked in. It would seem that the PO installed that little valve in the filler cap the wrong way around. Logically it would make sense that the 2 little holes would be facing upwards (so as to let air in on suction).

I took off the pump and the banjos. I took a syringe and checked all the lines. Oil was able to pass through all the lines. I then just blew with my mouth (yuck) in the opposite direction to check if the valves would close, which they seemed to do. I have also for now hung up the spider to see if anything will leak out.

I stripped the pump and everything looks near perfect. The pistons are free to move etc. I then setup a bench test and oil was pumped into all the lines. 3 lines with more oil than the other 3, which is as expected. I weighed the oil quantity of the 3 x 3 bags (the ones with more oil all weighed the same, and likewise for the other 3).

So my first question is ... in the engine casing you have 6 holes. According to the oil quantity pumped out the 2nd 4th and 5th holes (counting from the LH side) are for the piston oiling and the others the crank. Would someone be able to confirm this (I tried for ages to find the info, but had no luck).

Is there also a way to check if the engine casing passage ways are clear ?
Compression is good across all 3 cylinders being 125psi each

So now I'm left with 3 things that I can think of, which is to check the SRIS valves (perhaps the LH to RH path is blocked ?) And then perhaps there is something odd with the RH exhaust ? Not sure what I can check in there besides the baffle ? And then lastly, perhaps the actual channel in the casing is blocked ?

Any thoughts are welcome.

[sparkmark]

I've been able to answer some of my own questions, maybe this proves useful for someone.

Regarding the 6 holes, holes 2,4,5 (counting from the LH side) are for oiling the piston.

I was able to check that the passage ways were clear by injecting some oil into openings 2,4,5 and looking down the inlet. You can see the oil coming out of the small pipe that protrudes into the intake. (Note that on the LH cylinder it has 2 pipes. It's the one on the right of the intake where it feeds in from the pump.

Using the hanging test for the spider I can see that one of the check valves is no longer sealing. It's the inline one that feeds port 1 (far left). Tried to clean it but no luck.

I also found that the SRIS valve on the LH cylinder was blocked. So maybe that is what is contributing to the dryer exhaust on the RH side.

[Alan H]

Lots of info here - https://www.oldjapanesebikes.com/GT750_ ... e/page-A57 - about GT750 oil pumps and GT750s. This site too - https://www.pinkpossum.com/GT750/Oilpump.htm .
You're on the right track though!