Thurmal Coupling

[johnbirchjar]

Hi Guys,s'me again ,There isn't an earth wire on the Thermal Coupling on air cooled bikes,the two wires that run from the Block, down through the Coupling,and are soldered together in a ball to prevent them pulling back through the coupling,so my question is this,is the coupling earthed through being screwed into the chamber head? if this is so,is the Thermostat for the Temp Guage on Commanders earthed the same way?(only through the water jacket housing)J.B.

[Anthony Duffield]

John,

My water cooled Commander temperature gauge works by measuring the resistance of the sender to earth.

The sender, the thing with one wire and attached to the engine, has a certain resistance when cold, as the engine warms up the resistance changes.

The temperature gauge passes a small current through the sender to earth (the engine) as the resistance changes so does the current, the meter is calibrated the indicate a certain value in degrees C for a specific resistance of the sender.

It is important to make sure that the electrical connections between temperature gauge and sender are good as any poor connections (high resistance) will give an incorrect temperature reading, likewise the sender must have a good connection to the engine, give it a good clean and smear a little high temperature grease on the base for good measure.

I hope the above helps

Tony

[johnbirchjar]

Hi Tony,Thanks for the info:
Are the temp gauges specifically for Commanders to run off that particular sender,or will any old temp:gauge suffice,
and do aircooled's use the same system?J.B.

[BlackIP2]

John.
The air-cooled temperature gauge is totally different from the system on the water cooled engine. On the air-cooled there are two wires that come out of the engine just above the spark plug. Those wires have no electrical feed as they operate the temperature gauge by an independent micro-voltage system. I assume the water-cooled engine works as any other water cooled system and is not special to rotaries, whereas the air-cooled system works only for that engine.
Cheers
Mark

[johnbirchjar]

Ok,thanks for that.
So I gather I will need a different temp gauge,and how is that wired up to the thermostat(I am assuming that the temp gauge thermostat is the one with just ONE "mushroom"shaped connector?)
If the other thermostat is for the rad fan? I think I must have some sort of "switch" missing 'cos the fan "block" connectors and the thermostat prongs are both male ,(I think I may be in need of a Commander wiring diagram )any offers? .J.B.

[BlackIP2]

John
This is a link to Startright's technical page. Hopefully it still works as there is loads of useful info and downloads on there:

http://startright.co.uk/index.php?main_ ... 36kp2u0d42

[Anthony Duffield]

John,

Are you running a water cooled Commander?

Tony

[johnbirchjar]

Hi Tony, I have transplanted a Commander engine into my Classic.
Quite an undertaking, Firstly the engine was minus the Water Pump so I decided to fit an electric pump(the Norton Pump is such a pile of poo anyway)secondly 'cos I have a fairing off a Triumph 900 Sprint Tripple on the Classic the Commander Rad: is too wide to fit between the sub-frame mountings ,so a bespoke rad had to be manufactured,as did the Rad Mountings, Water Hoses,+ finding room behind the rad for the Electric Pump,'leclic power for said pump and Fan,all in all, not a job for the faint hearted .
Richard sent me pictures of his Classic look alike,but he retained the Norton Water Pump and his bike was "Naked" ,so a much simpler undertaking. Him fitting an electric pump to a Commander was an entirely different ball game,( being a qualified engineer with a fully equipped workshop must have helped )but I am nearly there, waiting for new Exhaust Manifold Gaskets are holding me up at the moment,lets hope it will be a worthwhile undertaking,I will report anon,J.B.

[johnbirchjar]

Hi guys,still waiting for answeres to my questions posted on Sunday ,
I tried to make sense of Grahams drawing of Commander electrics,may as well have been in Chinese ,so untill I get some answeres to the above, the project has ground to a halt 'cos I can't wire up the Electric Pump,the Fan or the Temp; Gauge,so answeres please guys,ASAP,rgds,J.B.

[Anthony Duffield]

John,

The sender for the temperature gauge is the one wire mushroom connector

The temperature switch for the fan has two connections only

On the diagram the temperature gauge item 10 is wired as follows:

GU sender mushroom connection
B is Negative
W two wires connected together is Positive

The lamp for illumination is connected B Negative and the two wires NG become live when you turn the lighting switch to the first position from daylight running to side light

Hope this helps

Tony

[johnbirchjar]

Hi Tony,Thanks for the info but unfortunately not a lot of help 'cos we are looking at a Classic's electrics not a Commander's,(the Ignition has only two positions) 1st is Ignition,Indicators,Horns ect;the 2nd is lights.
I have the Ignition switch out from the binnacle and have found a connector that is "live" when the Ignition is in the 1st position so now I have power,(it is also still "live"when I go to the 2nd position)so how do I now wire up the Thurmostat to the (new)Temp Gauge?
Colour codes confuse me so just Earth & Power (Black & Red)please rgds,J.B.

[johnbirchjar]

Further to the previous post,not to worry about the Temp:Gauge light 'cos the original wiring for this will suffice ,J.B.

[johnbirchjar]

Hi Tony,reading your post of last Saturday, am I correct in thinking that each Commander Temp: Gauge is calibrated for its"own" sender?so in fact they are a pair? (I hope not 'cos I've just ordered a new one )J.B.

[johnbirchjar]

Continuing on,my new gauge arrived today, ,and guess what ,included in the package was a new Sender ,compleat with wiring diagram .
In my quest for answers re:gauges,thurmostates,Senders ect,I have noticed that ALL(well the three Iv'e seen) new gauges come with a Sender,which lends me to believe that they are Calibrated together at the factory,and can only be used together as a pair,(which answeres my previous question to Mr A Duffield Esq.)
I don't suppose it will be long before I am back on the forum asking more questions ,till then,ride safe,J.B.