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How to measure engine temperature in air cooled RD350

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Hi fellow riders,

Could you please let me know where to measure the engine temperature at air cooled RD350, what is the acceptable temperature and what is the acceptable temperature difference between two cylinders?

Thanks a lot in advance

RDanary 1:
I notice no replies so I just thought I would give you my tuppence worth.

The gasket paste often used on RD cases is TB1104 and its spec sheet shows a max temp of 150C
That implies cases will under normal operating environment be less than 150C.

Cylinders will run hotter as will cylinder heads - most likely up circa 100C -150 C , depending on conditions. LC engines may run close to 100C I think.
So obviously depending what you mean by engine temperature - you will need to measure at different points of the engine as they will have different temperatures.
An engine running under light load will be cooler than one under full load  as will one standing still and idling etc -  so there are lots of variables like air temp etc.
One can use a thermal image camera with a suitable temperature range and point it at the area of engine to measure.
I have used a body temp gun to try to measure cylinder temp difference, but it only has a temp range of around 50C so I do it as it cools down and usually temp of each cylinder are within a few degrees of each other.
I am sorry I cannot be more precise but this may help you get a feel for the temperatures. A piston manufacturer may also advise you max cylinder temps as a source of information, if you contact one.

The critical temperatures are the piston crown and ring lands.  These are not directly readable but, I believe that fairly good corelation can be read between exhaust gas temp (egt) and cylinder head temp (cht).  There is quite a bit of info about both these methods of temperature measurement available online and systems are on sale.  For normal RD's, the engine is designed to run without problems in standard condition.  Temperature measurement is often used in racing engines that operate close to the limits.



Hi RD anary 1 and 5port,

Thanks a lot for your information.

The cylinder head temperature gauge is probably the most common type, temperatures are closely monitored by two stroke powered microlight pilots for some reason, can't think why! Egt as well. Cyl head type are just an extra washer thingy attached to cable and readout, obviously a thermocouple. There is a vid on youtube where a guy in the states has fitted one on each cylinder on his rd400 and makes interesting viewing when he rides it although in farenheight of course! I believe these are readily available in the states but have not seen them for dale here except on ebay.


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