Extra oil capacity / oil cooler WR450F

got inspired by indy's excellent thread on the jagg oil cooler:

Just finished adding an Oil Cooler for WR450

the jagg oil cooler only added about 8oz of extra oil to the WR450F, i wanted to add a fair bit more than that and a mate suggested adapting an oil catch can for three day rides and the like. this technically isnt an oil cooler, but it seems the breakdown of oil in the WR isnt so much from heat but just the single piston allows faster contamination of the oil. so figured i'd go the extra capacity with some additional cooling benefit, just not as much as a dedicated cooler.

so made up some brackets for a one liter oil catch can and this takes the oil capacity out to about 2.2 liters. i think this would be overkill for most situations... it only just fits, and does restrict the flow of air through the radiator fins to some extent. this didnt worry me as i rarely push the engine hard and my riding is not on those slow gnarly trails where cooling can become an issue... a 500ml oil catch can or smaller would be a much easier fit and restrict the air flow a lot less.

seems to have been working well so far for a dodgy brothers job that cost $120. most oil catch cans have an inlet and outlet for viewing the oil level, i bought hi temp gasket goo and the right screws to seal these off. had trouble with a slight oil weep from the base of the oil catch can. eventually had to take the top and bottom off, smooth the surfaces with wet and dry then make my own gaskets for a better seal. not a prob since then. was paranoid about oil leaks so used the gasket goo on joins, and doubled up on hose clips with each connection.


jagg oil cooler (on a crf450)




This was nicely done, but to me it looks like it would not work correctly as it appears to be laid out.

You have this tied into the return circuit, which I think is the best way to install a cooler, certainly, but not necessarily an additional oil supply.

The return pump moves oil about twice as fast as the feed so that as much oil as possible is returned to the feed tank as quickly as possible, keeping the sump "dry". This, both inevitably and by design, results in there being air in the return line quite often. So, as you appear to have it plumbed, it looks to me as if you've created a large air chamber in a high point of a loop in the return line, which will tend to trap air as it enters and force the extra oil you add to the frame tank. On the steel framed bikes, there is actually the physical space for nearly 2L of oil in the tank as it stands before any additional is forced back to the cam box out the pressure balance hose. Obviously, you'd be quite surprised by this were you to remove the dipstick on a 450, but there is room for it.

If you were to fill your aux tank from the bottom and take the exit line out the top, you would keep the tank full, but once the return pump starts moving air, the bubbles would bypass the oil in the tank, and your extra supply would find itself isolated and unable to move back to the feed side in the tank.

By filling your tank from the top and taking oil out the bottom, you would have incoming air forcing oil onward to the tank, but then again, a majority of your extra supply would likely end up in the frame as the system continued to operate.

IMO, if the tank stays on the return circuit, it should be relocated to the steering head area, filled from the bottom, withe a line out the top running to a fitting on the side of the frame tank where it flows back to the feed.

You have this tied into the return circuit, which I think is the best way to install a cooler, certainly, but not necessarily an additional oil supply.

thanks for the feedback. i tied this into the return curcuit figuring it should be fine as the jagg oil cooler works that way, but it sounds like you are saying the extra capacity with my setup makes the difference.

it seems to have been working fine this way for a few hours riding.... but after your comments i did check the dipstick. after idling the bike for 3 mins then turning it off as per the manual, i pulled the dipstick out and oil flowed out the top. so as you say the extra oil is being forced into the frame reservoir. interestingly, if i let the bike sit for a fair while, i check the dipstick again and the oil level is showing in the sweet spot, bang in the middle between the high and low markers.

as it stands now, what do you think the worst case scenario is with the current setup? if i understand correctly, oil will keep moving through the system fine, but i just wouldnt be able to check my oil level as per the manual's instructions?

do you think it would work better on the feed circuit? i thought once the engine was shut down the extra oil would run back into the crankcase and lead to pressure on gaskets etc when the bike was started, at least till the extra oil was pumped around the system?

thanks in advance for any info...

Oil runs back to the sump in these engines as they are built. There's a low pressure check ball on the feed circuit, but it's after the pump, so oil can and does leak past the pump shaft and into the sump in a few days. Also, when you refill, you fill the sump and not the tank (which I happen to think is at least rather odd). No damage come of this.

I think that the tank as you have it mounted would probably work on the feed side, which is a better place to add capacity, but you would want to run the line in from the feed fitting on the frame to the top of the aux tank, and run a third small hose from the top up to a 'T' fitting in the vent tube at the steering head. As long as oil in the frame was above the high point in the feed line, oil would flow through uninterrupted.

But the tank is a bit high on the bike, and I'd be more comfortable if it were lower.

I have been scheming on mounting the short 7" cooler on the downtube of my WR. It wouldnt hold nearly as much oil as the oil catch but some is better than none.

You did a nice job with your idea . I like it

Im a little surprised with the cost of 4 stroke rebuilds and how anal people can be about their bike oil that oil coolers arent a bigger deal

great idea, and with the inlet and outlet at opposite ends i assume you wont get the air collecting in the top of the reservoir like mine.

i figure its the smaller one. have they given you a price on it? any guess at roughly how much extra oil you'll be adding?


i figure its the smaller one. have they given you a price on it? any guess at roughly how much extra oil you'll be adding?

Given the external dimensions I'll guess the interior to be roughly 1"x6", which would be about 77cc.

Incidentally, while heat is a concern on longer rides with a small oil supply, good synthetics can deal with it pretty well. The real killer of engine oil in these bikes is the transmission. If the oil was not blended to deal with life as a gear lube, the shearing activity of the gears beats up the additives that keep your multi-grade oil as thick as it should be when hot, bringing it down as far as a grade and a half in less than two hours. As little as 6 years ago, there were only two or three oils on the market that had recognized and addressed this, but it's become more common now. Check out the shear testing on page 9 of this document and note the oils that stay above their rated minimums.

The smaller inline cooler retails about 70USD.

Its 2"x7" .Im thinking even if it adds only minimal amount of oil, it would help cool the oil which is a good thing.These bikes put out so much heat.Any thing would help. I would think the steel frame basically acts like a cooler itself as its right out in the cool air flow and the heat is pulled from the oil through the frame.I would never have the time or ambition or even need to do it,cause its much easier to change my oil, but I have thought the entire frame could circulate oil as a cooler on off road bikes?

I still like how much additional oil capacity you added. It would be nice to have some kind of fins on the can to help

Were/are you involved in racing cars? Until you posted it , I didnt know what a oil catch can was.

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