New extra M3W Dashboard

Chapter               ENGINE sensors

For the engine sensors I used the following parts

2 x CHT From Auber US for SYL-2831 ( TC-KCHT14 ) : each US$ 35

1 x Engine oil water temp sensor ( galvanic free ) from AUBER-US ( PT100A-NPT ) : each US$ 28.5

1 x Engine oil pressure sensor ( galvanic free ) from Amazon.fr

Transducteur Capteur de Pression, Akozon 1/8" NPT : 20,68

1 x Pressure switch ( the existing one )

Other parts

2 x Aluminium T-pieces 1/8-27 thread Amazon.fr

Qiilu Raccord en t de 1/8 "Npt, 3 voies 1/8" NPT each : 22

The T pieces are sold as aluminium. But that s Chinees aluminium.

In Chinese that is clearly another word than we understand, because they stick strongly to a magnet.

But actually that is a good thing so they are more strong than an Aluminium one.

Connection of engine sensors

The in Ian Brett s extremely helpful Alternative Parts list mentioned Billet sandwich plate MTGASP200X was not for sale at that moment and do have the problem that they are difficult for placing and maintaining easily the 3 sensors all together. With sending to France and import duties those sandwich plates are 44,78 + 10,74 + 20%. So thanks to UK citizens who voted for Brexit, this sandwich plate is 30% more expensive for us in the EU than those two T-pieces. So no business.

The fitting for engine oil-pressure ( most right one ) and Engine oil-temperature ( most left one ) with the original pressure switch ( in the middle ).

Although I used Tef-Gel as an electrical anti-seizing compound. Amazon.fr : 61.

The earth connection of the T-pieces to the engine was still OK. That earth-connection is only important for the existing pressure switch the other sensors are galvanic isolated.

The Tef-gel protects the aluminum a little bit against electrolysis between the aluminum T-pieces and the other Stainless steel sensors.

Tef Gel is also good to use with the stainless steel Rivets we have on our M3W on the aluminum body to prevent the typical aluminum rust under the paint at those places.

Because you will have to control this whole sensor construction once in a year at changing oil and/or filter you can keep a good eye on possible electrolyze between the T-pieces and the aluminum part of the engine and the other Stainless steel sensors.

Disadvantage of this construction

I should mention also the disadvantage of this construction.

Because it is a Cul de Sac for the oil, the temperature will rise very slowly, so you do not have immediately results.

That said you will have immediately temperature results and very accurate from the CHT sensors.

Stone guard

The whole connection is covered by a thick wooden pine-plate and a 3mm thick aluminum plate to protect this and the sensors, but also protecting the bottom of the engine. On my Honda AT and more off-road bikes you need a stone protection plate under the aluminum made engine.

Although having one wheel extra and not in front of the engine, why not here?

In France you have very often in the Pyrenees - where we live - and at entrances of houses and farms a dirt road where the 4 wheels of a car digs out the side so far that there is possibly not enough height for the M3W. To protect the engine a stone-guard is in our situation a preferable thing.

The stone guard is 20 cm x 50 cm x 2,3 cm and Tef-Gel bolted with 5 stainless M6 bolts in the existing frame.

The bitumen painted wooden plate is 2 cm thick and creates also some extra space for the pressure switch by making a hole in it.

Although the T-pieces-sensor-construction it selves feels very strong the stone guard gives valuable protection for the T-pieces and their sensors with cables connected.

You can also see small parts of the outside grey CAR-cover which I bought for 13 in the ALDI 😉

CHT sensors

I bought from Auber US also their CHT spark-plug sensors.

Spark plug sensors or CHT sensors do give the best information about the actual Cylinder Head Temperature of each cylinder. You always need two of them with a V-Twin to compare the two different temperatures.

The reason are these motor-bike V-Twin engine.

My Honda AT V-twin has on purpose with each cylinder a different cooling because one is in front, the other is in the aft.

The different temperature is created by a different air-fuel mixture for each cylinder.

The same with these S&S traditional bike engines.

The M3W Port side cylinder is original on a bike the far better cooled front cylinder; Starboard side is the original aft-cylinder.

The fuel-mixture in the front cylinder is different from the aft cylinder, so at the end both cylinder temperatures do have the same temperature on a bike as it should be.

But the M3W is not a bike and the temperature in both cylinders should be the same, there should be no difference. So I want to know the exact temperature and find out how you can change it, like you can do as a pilot in small aero planes. For instance when the plane rises or descends.

For everything on this engine it is important that both cylinders do have the same temperature.

Cylinder Temperature is related to the explosion push craft down of each piston and think about the imbalance you create with different temperatures on two cylinders.

Seeing the sturdiness how the S&S engine is build, I am sure it is not a real big issue, but when we can make it better it prolongs the life of these engines.

The delivered spark-plugs sensors are only in 14mm available. Our spark-plugs are 12mm.

So I filled and hard-soldered the 14mm hole with a same thickness copper-plate I had and with a special jewellery-makers saw ( my Partner has one ) I made a 12mm hole.

The connected hard wire to the copper ring, was very bad soldered, so I had to do this again too.

! also changed the Sparkplugs to Iridium ones from Amazon.fr - NGK DCPR7EIX : each 14,50

Making 14mm to 12mm CHT sparkplug sensors

CHT Result

I found that the max temperature will be around 170 175 ^oC.

It reacts very well on the power you use.

When the engine is warm, there is also not much significant temperature difference : 1%.

Of course the Port side cylinder stays always hotter than the Starboard side cylinder.

It is arguable if we have to change the mixture because of this small difference.

But knowing the actual Cylinder Head Temperature when you drive is great for finding other faults.

Not on the M3W but in most modern cars and expensive bikes it is even a very important part of the ECU-management system.

F.I. A bad and different Cylinder Head Temperature may cause performance issues such as a decrease in power, acceleration, and fuel economy. The performance issues may be only slightly noticeable in the beginning, but will get worse as time goes on.

Urban Cooling system

What is a discussion worth is the Air-ventilation cooling system designed for low speed.

It works perfect on my M3W, but the moment I stop the engine by turning the ignition key it also stops directly the cooling fan. The engine temperature will rise which is not good, when not controlled.

On my old VW transporter the cooling-fan and water-pump stays on for more than a minute regulated by a thermostat and relays.

I will design and make a time clock with a relay directly on the B+ which keeps the fan on for at least another 5 minutes, which is no problem for my 40Ah Varta battery.

Another solution is : Wait a couple of minutes and let the engine cool before you actually turn that ignition key.

That takes discipline and from my Turbo-charger on my VW T3 diesel I know I have to do the same but always forget it when I go for filling up the tank at a fuel station and want/ need to have a break.