Cool oil

A good case for fitting an oil thermostat IMHO.

So–no oil thermostat on your bike then, David.

However most triples have an oil cooler fitted and instead of 50C that you attained their maximum temperature would have been less than 50C–all other things being equal.

IMHO if you have an oil cooler fitted (as most triples do) then it is a good idea to fit an oil thermostat.

Just my two cents worth of course.

Hi Richard,

I’m in the process of building a Rickman framed T150. I’d value your opinion on whether I’m going to need an oil cooler, given that the Rickman has oil in the frame, although less than the 6 pints in the original tank. I’m in the south of the UK.

TIA,  Mike

Hi Mike,

The original spec for the cooler was to maintain a maximum oil temperature of 85C under conditions of an ambient temperature of 52C using WOT (wide open throttle) to thermal equilibrium (which we reckoned to take 10-15 minutes).

So under the vast majority of operating conditions the cooler overcools the oil.

Some people in temperate climates (such as UK) not fully exercising their right hand can get away without having a cooler fitted.

However you would only need ten minutes on the autobahn in summer to need some (but not all) of the cooling capability of the cooler.

And that is the rub—for the vast majority of the time you could probably be OK with no cooler but there could well be some instances where you need some of the coolers performance—but in all probability not all of its capacity.

In your situation I think I would play it safe and fit a cooler—but would also fit an oil thermostat to prevent the cooler overcooling the oil.

That is my view and my recommendation but– at the end of the day–the decision is yours.

HTH

Hi Richard and David,

Many thanks for your replies – really helpful. I’ve ordered the frame with oil in the frame fittings, but I might see if I can fit the original Triumph oil tank, as I suspect it holds a bit more oil. Also, the oil should warm up more quickly on short runs. In that case, I will fit the original cooler and a Madigan thermostat. Oil in the frame saves some hassle in fitting stuff, but I’m still a bit concerned about how clean the inside will be. I’ll be fitting a filter on the return line, but I see the ability to get the tank off and give it a good clean as an advantage.

Mike

Richard, out of interest where was the 85deg measured?. I’m asking because I’m measuring oil temp in the tank and I wonder how much higher it is within the engine e.g. at the bearing surfaces.

Hi David—the 85C oil temperature spec referred to the bulk oil temperature—that is the temperature of the oil in the oil tank.

Very localised oil temperatures –for example between the crankshaft and the shells would of course have been higher. But that oil would then be mixed with other cooler oil –for example spill from the OPRV –before returning tio the tank–either directly as in your case or via a cooler as per the standard configuration.

HTH

we did a direct comparison test a couple of years ago in march with air temp at about 12-15c. 2 bikes did a fast run together on open roads of about 35 miles mainly fast B roads 60-80 mph, same oil (morris 20/50 mineral) both bikes similarly tuned and set up (boyers, modified valve timing, re-sleeved carbs, etc). My T160 had the oil cooler blanked off with 2 pieces of cardboard and cable ties, my compadre’s t150 did not. We dipped the oil with a cooking thermostat when we arrived, my oil was around 60c, the oil coolered bike (a T150) was approx 50c.

On my T160 when the cooler is blanked off, there is a noticeably faster warm  up. I am ‘measuring’ oil temperature by noting the time that it takes for oil pressure to subside from the approx 100 psi plus that you get on a cold morning start. With the cooler in the airstream it can take at least 10-12 miles before we get an even 85 psi at 3,500 and above but with the cooler blanked off it will drop  to that level within 3-5 miles.

The other interesting point is that, even once warmed through, my oil pressure clicks up to 85 psi and stays there from 3-3,500rpms onwards. The only time its never stayed there at 85 psi was after about 10 laps of Dijon circuit at the Coupe Moto Legende weekend in around 28/30c when it would drop off with the revs.

But with the oil cooler blanked off (only on road use, never on track days) the oil pressure gauge will rise and fall with the revs (once warmed through)

When you think that the optimum oil temperature is about 85C it adds justification for the fitting of an oil thermostat.

If you do that you don’t need to worry about taking off the cardboard on a hot summers day (remember those?) when fully exercising the right hand.

Just my two cents worth of course.

A two-way tap at cooler inlet and Y branch at outlet saves blanking material and thermostat.   Most riders will know if it is a staggeringly hot day when about to climb Shap and therefore turn the cooler in circuit, otherwise in the British Isles we have freezing fingers, knees and fogged visor as we lick salt thrown up by wheels, so oil bypasses the cooler.    Contrarywise doubtless Texans notice typical San Antonio heat as opposed frozen gas governors and no electricity snowscapes, they can also turn a tap through a right angle.