Oil Pump System

[rwk]

Have a question on the oil pump system. Is it possible or known that injection oil from the tank can leak past the pump and check valves and wind up filling the crankcase?

I've had my GT750M since '79. It has been sitting for about 20 months and I recently went over it, checked stuff, new battery etc, and tried to start it. The engine locked against the starter and wouldn't turn. Pulled the plugs and found fresh oil (I use synthetic) in the combustion chamber on the left cylinder which had caused a hydrostatic lock. No bent rods, the engine never started. So I pulled the SRIS hoses and check valves out of the front of the crankcase. I drained 14 ounces of oil from the left cylinder, about 5 from the center cylinder and none from the right. So over the space of 2 weeks or so, I've bought new SRIS check valves & hoses, fitted them and let the bike sit for 5 days. Pulled the left check valve again and got about an ounce of oil out this time. It sure looks like oil is getting past the pump assembly. Anybody have any ideas on this? Thanks!

[parksie]

Not sure about the 750 but it definitely can and has happened on the T500 with badly worn seals on the bottom half of the pump

[Coyote]

Pull the banjo bolt on the oil line that feeds the crank on the left side (it's the lower one). Put something shallow like a jar lid under the line end. Wait a few days and check. If the jar lid has oil in it, then it's the check valve on that line end. This is usually a stuck open check valve. If that's the case, you will need to remove the other 5 banjo bolts and the oil pump. Now with the pump octopus in hand, flush the lines with plain old isopropyl (rubbing) alcohol from the manifold end. I use a cheap plastic oil can for this. I had to grind the tip a little to fit the small holes. DO NOT USE COMPRESSED AIR! It will permanently destroy the check valves. Flush the lines for a while. Now take the line end that was leaking and put it in your mouth. Try to blow back through the line end toward the manifold end. If you can, then the valve is still stuck open.
The check valves on the banjo line ends are a simple ball and spring, but generally are not repairable. The idea is: motor starts, pump pressures up the lines and the valves open to allow oil to flow. Motor stops: oil pump pressure stops and the check valves close.
Good luck!! and keep us posted.
One other thing. If all is well, fill the lines with your 2-stroke oil before mounting the pump.

[rwk]

parksie & coyote:

Many thanks for the information. Flushing the lines was going to be my next step, but thought I'd ask for some experience in the matter first. I'll do as you suggest and let you know! Thanks again.

[rwk]

Also, one other thing. Does anyone have a source or idea on a replacement hose for the one that runs from the oil tank to the oil pump? It appears to be pre-formed, but Suzuki says that it is no longer available. I've bought some 6 mm hose but nothing so far yet is strong enough to hold the radius by the pump without kinking. I've thought about putting a spring inside the hose at the bend, but that will be the last resort type of thing.

[oldjapanesebikes]

Does anyone have a source or idea on a replacement hose for the one that runs from the oil tank to the oil pump?

These (16810-31200) are still available from a couple of places - I usually pick them up from Reiner in Germany - just email him at GTReiner1@aol.com. Prices are quite reasonable, and fast shipping.

[rwk]

OK, thanks for the info!