HI Folks, been away for a wee while, but back now.

New to me K75S, seems to be getting water into the tank.

I have a new tank/cap seal. However water still getting in

I obviously have the pump-filter-output pipe-injectors working, as the bike runs well, UNTIL
I get water in the fuel, and the bike doesn't run well on water :/

How does the water going down the drain at the 9 oclock position get dumped ?
It must have a way of NOT being mixed with the fuel.

Sorry about my woeful state of ignorance,but is there another pipe inside the tank, or meant to be ?

BW Johnny Scotland

johnnyalpha wrote:HI Folks, been away for a wee while, but back now.

New to me K75S, seems to be getting water into the tank.

I have a new tank/cap seal. However water still getting in

I obviously have the pump-filter-output pipe-injectors working, as the bike runs well, UNTIL
I get water in the fuel, and the bike doesn't run well on water :/

How does the water going down the drain at the 9 oclock position get dumped ?
It must have a way of NOT being mixed with the fuel.

Sorry about my woeful state of ignorance,but is there another pipe inside the tank, or meant to be ?

BW Johnny Scotland

The 9 o'clock drain is into a pipe that passes through inside the tank and comes out underneath.....or should come out. If it isn't coming out only other place it can go is in the petrol. Run a little test on it and see what happens. Blowing into a straw is one way. If its leaking inside the tank its likely to be up high as otherwise you would have petrol leaking out the drain pipe.

But before you go at that take out the 4 screws you see when you open the petrol cap which should open back towards you, as in the hinge is at the rear of the tank. The whole cap assembly will lift out, just don't drop the screws. It should be seated on a watertight gasket that has a hole in it at 9 o'clock so any water can drain off into the hole. That should be the new seal you just put in?

If the hole or pipe is blocked then water can get in the tank easily.
With all the rain we get I see quite a few instances of contaminated fuel.

These photos show the piping for a K100 (1986?), however, it may not be the same as your bike, but it may give you an idea of what's going on...

Two photos from different angles.

I hope they help...

Wow these pics are amazing,thanks, so the pipes are solid plumbing not rubber ?  Is that a sectioned tank ?
By that I mean the piping leads directly to the outside of the tank at the RHS rear of the tank?

Need to use the bus for commuting to work until I get sorted out with this problem, of course ,at this time of year,it leaves very little daylight to work in.   Probably be the weekend until I can get round to it   In the meantime I have covered bike with a good solid waterproof cover.

Ho hum such fun !

Johnnyalpha

PS I take it that blocking the cap drain is not a good idea ?  water still gets in ?

Yes that was a real tank till the grinder got to it.
The plumbing is solid.
It goes to the RHS where a small plastic catch tray is positioned which drains to the RHS just to the rear of the pillion footpeg.
Don't block the drain as it lets water accumulate so that when the cap is opened you will see a heap of water go glop into the tank.

You don't need to worry about the drain plumbing inside the tank. Its all fixed aluminium tubing welded in place. If you're getting water inside your tank you probably need a new tank to cap base gasket. #8 in the diagram below which is oem part #16111453690. This is the bottom gasket that actually keeps the water out.

When you remove the whole cap assembly, you'll probably see a bit of aluminium oxidation come away on the bottom rubber seal. If the rubber is in ok condition, all you need to do is  clean all surfaces completely and coat with something like silicon grease (not sealant) and replace. Motorworks and others have the bottom gasket if it needs replacing.


This Chris Harris Youtube video shows how to rebuild the cap with a new seal kit but it doesn't deal with the bottom gasket.

Thanks for all the replies. A bit of a plumbers nightmare in there !!!!

I have a new tank seal in place,but no silicon grease,will fix that.

PITA that I won't be able get to grips with this until probably the weekend

Work the curse of the riding class !

BW J

OK, I got a hour or so of daylight, so I had a look at the tank.
Firstly I thought that a PO had deliberately blocked the hole with epoxy or something,I just could not get anything down
there. So I took a small nail and tapped it in very gingerly,it wasn't that hard,but it was gritty and crusty,then I had BREAKTHROUGH.
It all fell away and the hole was clear. Next step was to take some strimmer spool,and I was able to feed it right through until it popped out the bottom of the tank ))) I then danced a wee jig. Then cleaned and cleaned with brake cleaner and strimmer plastic.
Then I dropped a small amount of water on the edge of the cap and was gratified to see it head down the drain hole, a wee bit more and it did the same  
Then I used silicone grease to seat the tank rubber seal,under it and on top, then re installed the cap.
Quick whiz up and down and the bike ran really well.

I feel reasonably confident that this has solved the water getting into the tank problem,time will tell of course.
This process of keeping the drain clear will now be part of my maintenance routine.

I would like to thank everyone for the input, I am indebted to you all.

BW Johnny Z