Wet Sumping. .. a general query ..

[ajsph]

I also had a wet sumping problem on my G 11 CS, I fitted a newly refurbished oil pump, with a cover over the feed pump, but that didn't solve the problem, I then found out that the oil came through the oil filter channel and the non return valve, to the bottom of the crankcase, the non return valve was a new one purchased from the spares scheme. I tested the valve and found that the oil was seeping slowly through it. I put the valve in my lathe and took it apart easily, then I made a new insert with a proper seat for the ball and mounted it in the valve body and sealed it with solder. After I installed the modified valve I have no wet sumping problem, in 4 months there is less than 1/4 Pint of oil in the crankcase. It is now 4 years since I modified the valve and it still works.
Poul

[g80csp11]

can you give more details of where the oil filter channel is , and what what non return valve you are talking about . perhaps a part no so can look it up

[ajsph]

The oil filter channel is in front of the twin crankcase, and the non return valve has part number: 023331
Poul

[Rangy65]

Hi please note that the non return valve prevents oil running back from the cylinder head - Wet sumping usually occurs when oil under gravity finds its way past the oil pump on either twins or singles.

Thanks

Steve

[ajsph]

Hi Steve
I have been playing with twins for more than 40 years,and I have allways seen it as a myth, that the non return valve prevent oil from the cylinder heads to run back. If you take a look at the oilways , you will see that that the oilways to cylinder heads is a bypass from the oilway to the centerweb, and I am sure the oil from the cylinder heads, will run down to the centerweb before it runs to the non return valve.
Poul

[ajscomboman]

Although it's referred to a non return valve, once the oil has passed into the thrower/ centre web feed and onto the heads, any oil up top can bleed back into the crankcase reservoir and then into the cam follower metering jet and down into the sump. The valve realistically speaking is a posh metering jet. What it is designed to do is seal via the ball and spring to prevent wet sumping. If it doesn't seat correctly then you will get weeping.

[56G80S]

"Japanese bikes turned up with this whole idea of riding a few thousand miles before needing to do work"

Odd, the manual for my Yamaha XJ600S, 1994, tells me that I should adjust and lubricate the rear chain at every 500 miles. I've fitted a Loobman at the same time as new chain/sprockets, seems to do the job and very simple.

JohnnyB

[jackstringer]

"Japanese bikes turned up with this whole idea of riding a few thousand miles before needing to do work"

Odd, the manual for my Yamaha XJ600S, 1994, tells me that I should adjust and lubricate the rear chain at every 500 miles. I've fitted a Loobman at the same time as new chain/sprockets, seems to do the job and very simple.

JohnnyB

Yup, most have that kind of thing bits it's not as much fettling as bikes of yore. I can get 500ish miles done in a days riding so it makes sense to check the chain every time you go put. Lube if needed.

Before the Japanese bikes came along you didn't get much in the way of warranties. If it blew up 5 miles down the road it was your problem. Yamaha at least had a 6 month warranty. My uncles XS750 made.good use of that, the wheels and mudguards were made of cheese.

[Harry44]

How much does choice of oil make a difference to wet sumping?
I ran my G80 on 20/50 when I first got it and it wet sumped badly.
Now I run it on straight 50 it's barely a problem.

Have others noticed a difference ?

[g80csp11]

I think you answered your own question , multigrade oil is much thinner when cold than SAE50 and therfore leakage past the pump shaft , gears etc.. is worse