Author Topic: Oil tank modification  (Read 959 times)

Offline Brian

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  • Mt Gambier, South Australia.
Oil tank modification
« on: 28.03. 2009 00:22 »
Dont you just love the word modification, it can imply a sensible improvement or a total stuff up. Hopefully this is the former.

Some time back we had a thread covering the problem of some oil being blown out the engine breather. While this is not a major problem it does get a bit annoying when you pull up on a friends new driveway and one or two drops of oil drip on the ground. Plus it can over time make the underneath of your engine messy.

Some overcame this with a small bottle behind the engine with the tube from the breather running into it. I did this on my 61' A10 and it worked very succesfully. Every 1,000 mile or so I would get about a teaspoon full of oil in the bottle.

I decided to go further with this and make a permanent modification. I have done three now and wanted to wait until I had done a few miles on the bikes before I put anything on the forum just to be sure it all worked ok. I have done two plunger models and one swingarm.

Start with the plunger bikes.

You need a piece of steel tubing about 1 foot long. I used 3/8" OD tube because it is what I had plus 3/8" ID rubber tube is readily available.
Drill a 3/8" hole about 1" outward of the existing tank vent outlet in your oil tank. I cut a V in the top plus drilled two 1/8" holes just down from the top. Push the tube up into the tank until it hits the top and weld in place. Ideally you do this before you paint the tank but with care you can do it as I have and touch the paint up with a pressure pack. The painted bit is at the back and underneath so is not visible.
Next run a tube from the engine breather to the new piece sticking out the bottom of the oil tank and from now on the engine breathes into the oil tank.

I have done few hundred miles on the A7 I first did and it has been very succesful. The underneath of the bike is totally dry and there is no sign of any oil coming out the oil tank vent.

On the swingarm model I put a piece of tube at the top as you can see in the photo. The tube runs down behind the battery and under the gearbox to the engine breather. This one you definitely have to do before you paint the oil tank.

On both models the modification is not visible unless you get down and look up under the motor and then you can see the tube.

So there you go. Its not something that is absolutely necessary but, if like me, you want your bikes as oil tight as possible then it definitely helps.

I was going to insert the photos rather than put them on as attachments but I couldnt work out how to do that.