Oil Tap with Cut Out Switch

On many of the older classic bikes, when left standing for a while, a very common problem is for the oil in the oil tank to drain past the oil pump into the engine sump. In time, a significant amount of oil can accumulate in the sump. This will cause problems with starting and in really severe cases can cause hydraulic lock resulting in considerable damage. If the engine can be started, because the return side of the pump is larger than the feed side, eventually the oil will be returned to the tank. However, while this is happening it will be thrown around by the flywheels and up the bores past the pistons where it will burn and create a lot of smoke. It will also probably be pushed out of the engine breather making a mess on the bike and all over the ground.


So - what to do? There are a number of options:

 

  • Drain the sump before every ride
  • Overhaul the pump to reduce (or hopefully stop) leakage
  • Fit a non return valve (already standard fitting on some machines)
  • Fit an on/off tap between the oil tank and the pump

 

The last of these options is very commonly seen fitted to a wide variety of makes and models of motorcycles but has one major drawback - the rider must remember to turn it on before starting the engine! As a solution to this potential problem, The Magneto Guys have now produced a combined oil tap and switch which can be used with either a magneto or battery/coil system. This will ensure that, if the oil tap is 'off', the switch will be stopping the flow of sparks so the engine cannot be started!

Description of the Oil Tap with Cut Out Switch
The oil tap incorporated into this Oil Tap with Cut Out Switch is either a 1/4" BSPP or 3/8" BSPP ball valve fitted with a modified handle. For each of the two sizes, there are two versions offered:

Male/Female

Female/Female

The microswitch used in this Oil Tap with Cut Out Switch is housed inside a custom made nylon body. It is fully waterproof, protected to IP67 and rated at 10.1A @ 250v ac. A cam plate is attached to the oil tap handle so that, as the tap is turned on and off, the microswitch is automatically operated in such a way that the engine cannot be started until the oil tap is turned fully on.
How the Oil Tap with Cut Out Switch Works
When the Oil Tap is in the 'closed/off' position preventing oil flow, the cam plate makes contact with, and presses down, the microswitch plunger protruding from the top of the nylon body. As a result, either:
1: the magneto will be shorted to earth OR
2: power from the battery/ignition switch to the coil will be interrupted 
In either case, it will not be possible to start the engine.
When the Oil Tap is in the 'open/on' position allowing oil flow, the cam plate moves away from, and releases, the microswitch plunger. As a result, either:
1: the magneto cut out will be disconnected from earth OR
2: power from the battery/ignition switch will be connected to the coil
In either case, it will then be possible to start the engine.

Note that the shape and position of the cam plate ensures that, even with the Oil Tap in mid position, the ignition system is still prevented from working. The engine cannot be started until the Oil Tap is in the fully open position resulting in a completely clear path for the oil to flow through the Oil Tap.

These pictures show the 3/8 Oil Tap with Cut Out Switch. The 1/4 taps are very slightly shorter. All taps use much the same size hexagon for the main body and all the handles and nylon bodies are the same dimensionally.

Fitting the Oil Tap with Cut Out Switch
The Oil Tap with Cut Out Switch is usually fitted either at the top of the feed pipe on the oil tank or at the bottom of the feed pipe on the crankcase. Another possibility is to fit it in the middle of the feed pipe although this is not recommended as either of the first two options provides a more solid fitting. The Oil Tap with Cut Out Switch uses 1/4" or 3/8" BSPP threads on the entry and exit sides which are standard fitting on most British Classic and Vintage motorcycles. The details of every installation will be different depending on the type and size of the feed pipe, the route the feed pipe takes and of course the available space. Many different types of adaptors are available as standard 'off-the-shelf' items which use BSP threads including:
  • BSP to hose tails (for use with flexible oil pipes)
  • BSP to compression fittings (for use with copper oil pipes)
  • BSP to BSP right angle elbows
  • BSP banjo fittings
  • BSP to NPT adaptors
Most of these adaptors can be obtained in plain brass, plated or stainless steel as preferred. With such a large variety of options available, The Magneto Guys have chosen not to supply any adaptors with the Oil Tap with Cut Out Switch. Readily available from many outlets, it is left to the purchaser to choose and source the adaptors to suit their particular installation.
CAUTION: The nylon body and/or the handle can be removed if necessary to make installation easier. However, be aware that there is a small spring between the switch body and the tap - take care not to lose it! Also, if you do remove the handle, it's a good idea to use a drop of Loctite when the screw is replaced. Old bikes vibrate and it would be annoying if the handle fell off.....

Wiring the microswitch into the ignition system can be achieved without the need for any dismantling. There are three screw terminals marked A, B and C. 

Wiring for use with a magneto ignition system

Terminal A: not used with magneto ignition systems

Terminal B: not used with magneto ignition systems (but see note* below)

Terminal C: add a new wire (shown in blue) to the magneto’s cut out terminal

 

 *Note: When used with magneto ignition systems, one side of the Switch is Terminal B which is connected internally to the  body of the Tap itself. This means that the necessary connection to earth on the bike is normally achieved automatically when the Oil Tap with Cut Out Switch is screwed into either the oil tank or the engine crankcase as required, both of which are already earthed. This removes the need to add an extra wire. However, if the oil tank is rubber mounted or if the Oil Tap with Cut Out Switch is fitted to rubber oil pipe on both sides, it will be necessary to add a new wire (shown in dotted grey) from Terminal B to a good earth connection on the frame or the engine.

Wiring for use with a battery/coil ignition system

Find the original wire fitted between battery/ignition switch and the HT coil (shown in dotted black) and then remove it.

Terminal A: add a new wire (shown in red) from battery/ignition switch to terminal A on the Oil Tap with Cut Out Switch

Terminal B: not used with battery/coil ignition systems

Terminal C: add a new wire (shown in green) from Terminal C on the Oil Tap with Cut Out Switch to the HT coil


CAUTION: When used with battery/coil ignition systems, connections to Terminals A and C MUST be made as shown. DO NOT SWAP THEM OVER! Terminal C is connected to Terminal B (internally earthed) when the oil is turned off and so this would result in a dead short!

Most twin cylinder magnetos are fitted as standard with a cutout terminal which is normally connected to a wire taken up to a push button cut out switch mounted on the handlebars. The wire from this Oil Tap with Cut Out Switch can be connected to the same terminal on the magneto. The original cut out switch can continue to be used as before - or simply turn the tap off and automatically stop the engine at the same time. Some single cylinder magnetos have a similar cut out terminal as standard but if one is not fitted, The Magneto Guys can provide a range of Points Caps with Cut Outs  - available in our Sales section.
HOW TO BUY: These Oil Tap with Cut Out Switches can be purchased direct from us, the designers and manufacturers. For all customers, both in the UK and overseas, this price includes postage/packing. A full invoice will be included with all purchases. Payment can be taken using PayPal by clicking on the relevant Buy Now button below.

Please note that any of our Oil Tap with Cut Out Switch versions can be used with either magneto or 6/12v battery/coil ignition systems - no external relays are required.

PLEASED TO REPORT - ALL SIZES AND TYPES NOW BACK IN STOCK!!

But be quick! They sell out fast!

ONLY £ 49.00 incl. P&P to anywhere inside the UK!
See below for overseas sales
FOR UK SALES ONLY:
Click this button to buy
1/4" BSPP M/F Oil Tap
with Cut Out Switch
FOR UK SALES ONLY:
Click this button to buy
1/4" BSPP F/F Oil Tap
with Cut Out Switch
FOR UK SALES ONLY:
Click this button to buy
3/8" BSPP M/F Oil Tap
with Cut Out Switch
FOR UK SALES ONLY:
Click this button to buy
3/8" BSPP F/F Oil Tap
with Cut Out Switch

Sorry - 3/8" BSPP F/F version OUT OF STOCK

More expected end of October

Overseas sales always welcome! Please check: IMPORTANT NOTES FOR OVERSEAS CUSTOMERS