Yamaha TRX850 Enthusiasts Forum

Ok I know this topic answered in the past, and the answer was a definitive NO, however I'm using the TRX in a offroad buggy.

The engine is worked (878 kit, 41mm flatsides, increased comp, ported & flowed head etc) and is mounted behind the drivers seat, so it doesn't receive much air flow at all if any.

For cooling I am using a 2 row alloy Honda Civic radiator and a 12 inch thermo fan behind it.

As I'm using such a larger radiator, woulld this be sufficient or would members here recommend I also run an oil cooler?

the engine runs pretty cold standard and has quite a lot of oil in it. Also you are adding a larger radiator, I cannot see that an oil cooler would be needed

As Con Rod says, you`re already running a larger radiator, why not drill and tap the sump drain plug and fit a sender wired to an oil temperature guage first, see what temperature your oil gets up to?
If it runs too cool you`ll be losing power.
An example:

http://www.demon-tweeks.co.uk/motorspor ... npt-thread

Cheers guys. Any idea what's considered the normal oil operating temp?

Semi synth`s around 100 to 110 degrees C, fully synthetic between 110 and 120 C as a good guide.
You want oil temperature above the boiling point of water to `dry` out condensation.

Perhaps this might help
The std TRX thermo fan cuts in at 102 to 108 deg C.
It cuts back out at 98 deg C.
The thermostat itself opens at 80 to 84 deg C and it should have valve lift of min 8mm at 95 deg C.
With the larger radiator, you may find it running cooler.
Perhaps your local radiator guy can reroute the internal feed tubing of the radiator to increase/decrease the thermal transfer as in the difference between european models of cars radiators and aussie radiators.
cheers
fung

Run an air duct to around the oil tank - job sorted