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lorenzo.imbesi
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VBMWMO #8560
Joined: 08/04/2013
Posts: 151

dear All,
I own a R75/5 SWB and today I found a good oil stain on the floor. Looking in detail I got where it is from: there's a hole on the back of the side of the oil pan and I am wondering if it is missing a bolt or some kind of cap, or it should stay like that. Please find a picture here below.
What do you think?

I guess this is where the leakage is coming from: is it something normal I should live with?

Thank you for your kind help!

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Dan McCarthy
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Joined: 03/04/2013
Posts: 47
Hi Lorenzo, That is the drain

Hi Lorenzo,

That is the drain hole for the shallow pan that sits directly below the gearbox. It's part of the engine block casting, and catches any oil that gets past the rear engine oil seal - if you look where the clutch cable enters the engine from the right hand side of the bike (with the bike on the sidestand) you will get a good view of where I mean. The "pan" should always be dry, and oil here is a sure sign of a leaking seal - the more oil, the worse the leak. I've had airheads that always carries a bit of mist here, but if you've got oil dripping out through the overflow I'd suggest your bike needs attention.

Dan

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6540
As years went by, the later

As years went by, the later models have a full slot across there...the engine mount bolt is basically exposed except where it enters the house on either side near the frame.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

lorenzo.imbesi
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VBMWMO #8560
Joined: 08/04/2013
Posts: 151
oil leak

Thank you Dan. Actually I recently replaced the gasket of the oil pan and I believe to have sorted out all the oil leaks. This is starting worring me..

Dan McCarthy wrote:

Hi Lorenzo,

That is the drain hole for the shallow pan that sits directly below the gearbox. It's part of the engine block casting, and catches any oil that gets past the rear engine oil seal - if you look where the clutch cable enters the engine from the right hand side of the bike (with the bike on the sidestand) you will get a good view of where I mean. The "pan" should always be dry, and oil here is a sure sign of a leaking seal - the more oil, the worse the leak. I've had airheads that always carries a bit of mist here, but if you've got oil dripping out through the overflow I'd suggest your bike needs attention.

Dan

mark_weiss
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Arizona
Joined: 11/17/2013
Posts: 172
There are two sources of oil

There are two sources of oil which can run down the block, onto the roof of the oil sump, and then leak from the weep hole at the back of the engine block. One possible source is the rear crankshaft seal. This seals from the engine block to a machined surface on the flywheel. Often this leak is not too bad and can be lived with through periodic cleaning of the area at the top of the oil sump, beneath the transmission. The other leak source is the cover for the oil pump. This is below the cranskshaft seal, at the back end of the camshaft. This is a pressurized leak and is likely to grow worse if left alone.

I recommend cleaning the area under the transmission and then monitoring how rapidly the oil returns. Whichever seal is leaking, replace them both at the same time. Access to either one requires the exact same work, so it is worthwhile to renew them together.

Another thought, be certain that the oil is engine oil. Transmission oil generally smells bad (sulphur) and the gearbox has a few potential contributors to your mystery. The most common are leaks from the neutral switch and leaks from the clutch pushrod.

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Mark
qualitycycleservice.com

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6540
Transmission oil can also

Transmission oil can also leak into this area past the input shaft seal.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

mark_weiss
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Arizona
Joined: 11/17/2013
Posts: 172
The input shaft seal is

The input shaft seal is generally a very, very, slow leak. The seal is in a non pressurized area and is above the oil level. The other two transmission leaks are quite common, especially the neutral switch. The N switch can leak from not only at its sealing surface, but through the switch itself.

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Mark
qualitycycleservice.com

mark_weiss
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Arizona
Joined: 11/17/2013
Posts: 172
Oops, got carried away. I

Oops, got carried away. I forgot that one of my /5s has a later 5-speed box. The original /5 4-speed gear boxes have the neutral switch in the rear cover, not underneath, so for a 4-speed, a leaky neutral switch is not too likely.

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Mark
qualitycycleservice.com

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