Oil Cooler

[Richard Ludwell]

Hi Rubberchicken..........hope you are well.Would like to know your opinion on the use of an oil cooler for a NX650. This would be inserted between the return oil pipe from engine and the underneath side of the oil tank. I totally agree with your thoughts re oil problems, my dominator is a NX650T (1996) RD08 with 53000 miles. I have had two camshafts with two sets of cam followers fail in approx: one year. Both failures were due to the lack of OIL getting up to the cam and followers. On the second top end re-build, I checked the external oil pipes for any obstruction, the two pipes were OK. When I blew through the oil input pipe (the one that feeds from the bottom of the front frame tube) in its natural bent shape there was one hell of an obstruction but when the pipe was straightened out there was'nt an obstruction. I carefully parted the flexible tube from steel tube and guess what I found....a flap of rubber breaking away from the inner wall of the pipe,this obviously constricted the flow of oil to the oil pump. I had a length of clear re-inforced hose, cut a length to that of the flexible part of the oil pipe, connected all up and started up engine. Oil was fully restored to the cam and followers. I have also changed the oil pump. By the way I don't hear of domie owners cleaning the oil strainer screen in the crankcase (the one under the oil pump). There are three oil filters/strainers, the paper filter on the right upper side of the crankcase (renewed on oil changing), the oil strainer in the bottom of the frame tube and the oil strainer under the oil pump in the crankcase. On the second top end re-build I checked cylinder bore/piston and decided to renew the piston rings glaze bust the bore. Well my friend I think I have taken up enough of your time, but would like your thoughts on oil cooling.

Cheers Richard.

[Rubberchicken]

Ouch... That little rubber flap is nasty.

I've toyed with fitting a cooler, I even bought one, had it in the shed, only had to find some time to figure out how to put it on... Which somehow didn't happen, you know how it goes. So I bought a GS instead which came with one from the factory.

But yeah, cooling helps. A friend of mine has a 2CV cooler with thermostat on a XL600 that spent 27.000 km going 'round the sahara. Bike hardly ever gets above 90 degrees oil temperature even on the motorway, which is pretty much perfect.


(There it is, underneath the headlight.)

The 2CV cooler is quite big, so you'll need a thermostat of some kind (lockhart in the states makes a nice one, if you can find it) or you'll never get the bike warmed up...

You can buy coolers ready made for the NX (Egu Motoren in Germany do one), they are smaller, about half the size of a 2CV cooler, and without a thermostat. Warming up takes a bit longer, and you might have to cover the cooler with a bit of cardboard in the winter...

The cooler goes in the return line, as you said. Getting an oil temperature dipstick is a very good idea too, so you can see what's going on.

[cafe650]

Ok I know I am not Rubberchicken, and I also know I am new to the Domi owners brigade, but, and this is of course a big but! if oil cooling was a problem on these engines, don't you think that Honda would have fitted a cooler to the domi or its predecessors? how long have they made the domi and not fealt the need?
Warm oil is good oil, it thins and as such moves easier, getting to all the important parts, and so under normal use should not in itself require cooling, of course this is different if the engine is being stressed in abnormal use as in competition. I feel the big factor that needs to be adhered to is regular oil and filter changes, your problems weren't caused in themselves by hot oil, they were caused by a blockage, an oil cooler would have made no difference.

[Rubberchicken]

To put the question in another form, how long have they felt they could get away with it and save cost...

The bike as-is may be good enough, but it can always be made better. In my opinion fitting a cooler and thermostat makes it better, as the cooling for the NX really is a bit marginal.

Warm oil is good. But there's warm and there's too hot. 90 degrees is good for regular 10W40 semisynthetic. 120 degrees is too hot, and 120 degrees isn't hard to reach at all after an hour of 75 mph cruising speed, in the summer. (Mind you this is 120 degrees at the dipstick, in the head things get quite a bit hotter.)

[mattnx650]

stp oil treatment very good for the cams dont fin out add it to your oil does wonders also would a 12v wired fan cool these engine's down?

[squirrelciv]

Got to admit I'm no fan on fitting an oil cooler to a standard motor. The doubts in my mind are, how is the oil forced through the cooler? Gravity? Pushed through? sucked through? The second two options will effect the flow around the all important parts or work rate of the pump as well as the increase in viscocity the cooler oil will have. Also what allowance for the coolers volume do you make?
Now A higher compression head or a higher revving motor, now thats a differant case. now we're asking a major component in the engines temperature control system to work harder and as such it might need some help
If you ride in the desert, or in a hot city for long periods then maybe, but for me at least, pootling along at 4-5k rpm, I'll leave things as Mr H desogned them

[Rubberchicken]

Got to admit I'm no fan on fitting an oil cooler to a standard motor. The doubts in my mind are, how is the oil forced through the cooler? Gravity? Pushed through? sucked through? The second two options will effect the flow around the all important parts or work rate of the pump as well as the increase in viscocity the cooler oil will have.

Actually, it won't.

On this engine you can fit the cooler in the return line. That way you have the primary oil pump driving all the important stuff, and the scavenger pump is just pushing oil into the oil tank, through the cooler.

Re: the increase in viscosity, that's kind of the whole point of the exercise, really... Cooling down oil that's getting too hot and too thin.

[mattnx650]

hi rubberchicken what oil cooler will fit on these bikes so i can look around for one

thanks matt

[Rubberchicken]

Anything you can stow away somewhere, really...

The 2CV cooler is a bit of a tight squeeze given that you can't fit it in the nose, and it really needs a thermostat. The usual thing is something half that height.

Here's a link: http://egu-motoren.de/onlineshop/mot...87d0d9d70d.php
(PS: They also do a 700cc conversion for the NX )

This one comes ready to bolt on with all the fittings, but the basic idea is to fit it in the return line, the metal pipe that goes from the right hand lower front of the engine to the oil tank in the frame. It's a metal pipe that you can saw through and slip oil lines onto, then it's really just a matter of where to put the cooler. Along the downtube under the tank is a good spot, but I've seen them fitted squarely in front of the bashplate as well.

[mattnx650]

thanks for that mate will look into it

matt