Oil temps?

[AZRedhawk44]

I think you got some good advice in this thread. But here's my randomly arranged thoughts...

The other thing to consider is that you added pressure drop in the oil system by adding the cooler. If you add a thermostat on top of that, it'll be additional pressure drop. Its not just the oil temp to the bearings to consider, its also the oil pressure to the bearings. At lower rpm, the oil pump will struggle to deliver the right pressure/flow especially as you add more restriction.

Interesting idea.  The oil cooler holds 150cc of oil, and instead of filling the conventional 2.0 or 2.1 quarts for this bike (different literature suggest two different numbers), I filled to 2.25.  Since I basically added another 150cc of oil to the total volume, wouldn't I have the same pressure?

Also, normal oil cooling flow (without the cooler) on this bike is to take the output from the bottom of the engine's sump/pump system, run it right up to the top of the frame under the gas tank and into the frame, then let it trickle/sit in the hollow frame as the bike frame is passively air cooled, and the oil is gravity-fed back down to the bottom of the frame where it is then sucked out, filtered and reintroduced to the top of the cylinder head.

With the new cooler, the output from the bottom of the sump/pump is piped directly into the oil cooler first, then ran up to the top of the frame and the internal reservoir and on through the rest of the system.  Could this then mean that the lower oil temp in the cooler creates increased pressure on the oil pump?

The head is the hottest component on the engine, so it doesn't really reflect the oil temp to main & throw bearings, under piston squirt, or cam bearings. But you still don't want the hot head degrading the oil prematurely and wearing out valve seals.

Air cooled engines have to be designed to run at a wider range of temperatures than a water cooled engines. So either way, a properly designed engine should be good to go, but if you are in a hot environment, then it was probably a good idea.

Gotcha.  Sounding more and more like it's a great idea in AZ when we go out to play in 90+ temps, but a bypass switch might be in my best interest.  Again, more data will be key here.  Need to find out the actual oil temp rather than the cylinder head temp at the oil line.

The manual might have been written before the latest standards came out or could be tested.

This statement is directed towards the totally unrelated Tiger and the synthetic oil API/JASO standards discussion?  The only reason I brought that bike up was to counter the idea of synthetic oil in a 21 year old dirt bike.

You might also consider a thermostat for that external oil cooler. Check with the place you got it, they might have something like this to fit:

http://vwparts.aircooled.net/Engine-Oil-Thermostat-p/oil-thermostat.htm

Covered in the OP.

[Firethorn]

Really? I did not know that.

Mileage may vary.  I've been told by a number of motorcyclists that they've run energy-conserving oil through their bikes without a problem, so it 'might' be overstated.  If you experience problems just changing back to non-friction modified oil should fix it.  

I still shop for the right oil though.

With the new cooler, the output from the bottom of the sump/pump is piped directly into the oil cooler first, then ran up to the top of the frame and the internal reservoir and on through the rest of the system.  Could this then mean that the lower oil temp in the cooler creates increased pressure on the oil pump?

Maybe, if the oil cooler's pipes are of a larger diameter than the original piping.  The additional oil is another way to help keep it cooler.

Gotcha.  Sounding more and more like it's a great idea in AZ when we go out to play in 90+ temps, but a bypass switch might be in my best interest.  Again, more data will be key here.  Need to find out the actual oil temp rather than the cylinder head temp at the oil line.

Depends on the temperatures.  Synthetic oils can generally withstand higher temperatures and flow better when cold.  As such, the need to keep the oil right at 180F is reduced.  With the temperature change you've noted, the only thing you might want to do is switch to a slightly lighter oil - I'd keep the second number right where it is, simply drop the cold side one grade.  IE instead of 30W50, 20W50 synthetic.

The only reason I brought that bike up was to counter the idea of synthetic oil in a 21 year old dirt bike.

I think the core of that conversation amounts to 'synthetic's great, no matter the age of the bike, but you just need oil that's suitable for wet clutches, which not all oils are'.

[drewtam]

Interesting idea.  The oil cooler holds 150cc of oil, and instead of filling the conventional 2.0 or 2.1 quarts for this bike (different literature suggest two different numbers), I filled to 2.25.  Since I basically added another 150cc of oil to the total volume, wouldn't I have the same pressure?

Also, normal oil cooling flow (without the cooler) on this bike is to take the output from the bottom of the engine's sump/pump system, run it right up to the top of the frame under the gas tank and into the frame, then let it trickle/sit in the hollow frame as the bike frame is passively air cooled, and the oil is gravity-fed back down to the bottom of the frame where it is then sucked out, filtered and reintroduced to the top of the cylinder head.

With the new cooler, the output from the bottom of the sump/pump is piped directly into the oil cooler first, then ran up to the top of the frame and the internal reservoir and on through the rest of the system.  Could this then mean that the lower oil temp in the cooler creates increased pressure on the oil pump?

Hmmm.

I don't quite understand the 2nd paragraph. It sounds like you got two pumps (1 to pump from sump to frame, and 2 to pump from bottom frame to engine).
But that seems unlikely.

Maybe you are saying one pump goes from the sump, through the frame and into the engine. That sounds more likely.

Assuming 1 pump the restriction would work like this...
Pump outlet ~300kPa
Frame outlet ~250kPa
Pressure to bearings ~200kPa

Adding a cooler may add restriction
Pump outlet ~300kPa
Cooler Outlet ~280kPa
Frame outlet ~230kPa
Pressure to bearings ~180kPa

In line restrictions are always additive. If its a positive displacement pump, like a gerotor style, maybe that just means the pressure at the pump jacks up to get to the same volume flow. In either case, the pressure to the bearings never goes up.

I gotta get to work, can't explain further right now...

[AZRedhawk44]

Hmmm.

I don't quite understand the 2nd paragraph. It sounds like you got two pumps (1 to pump from sump to frame, and 2 to pump from bottom frame to engine).
But that seems unlikely.

Maybe you are saying one pump goes from the sump, through the frame and into the engine. That sounds more likely.

There's only one pump, but somehow it generates enough pressure to lift the oil from the bottom of the engine to the top of the frame... as well as then to push oil up the pipe to the top of the engine.  I'm a bit fuzzy on how one pump can feed multiple paths.

[drewtam]

There's only one pump, but somehow it generates enough pressure to lift the oil from the bottom of the engine to the top of the frame... as well as then to push oil up the pipe to the top of the engine.  I'm a bit fuzzy on how one pump can feed multiple paths.

Ahh, it might split the flow, or push through in series. Whether is flows in parallel or series can make a difference to how one figures the pressure drop impact.

[DustinD]

It takes about 1 psi to lift oil three feet, 1 psi can lift water 2.31 feet.

Oil pumps can feed multiple paths in parallel because a lot of the resistance to flow is at the ends of the path. This naturally balances the flow to about what the engineers want it to be. In ground lawn sprinklers work on the principle. Edit: I guess you are referring to the dry sump, I will go look that up.  http://www.honda-xr650r.com/tag/oil-pump/ has an oil diagram, I am guessing that the oil cooled models are similar.

Another idea for temp control could be to block airflow to the cooler on the highway if you are riding on a cold day.

My 2002 XR400 has an oil cooler, I have never worried about the issue whether it was 100+ or about 0F. The only difference is I make sure the engine is fully instead of mostly warmed up when it is cold out. I have heard of many people riding their dirt bikes in well below freezing weather without issue.

[Larry Ashcraft]

Harley clutch is in a separate case, no worries about synthetic engine oil.

Yeah, the clutch is in the primary case.  Most riders and independent shops use Mobil 1 20-50 V-Twin in all three (engine, transmission and primary) although HD sells a primary oil.  I've also heard that Redline Shockproof is the best transmission oil.  I'm going to try that soon.

Off topic, I know. 

[JonnyB]

I have a Suzuki DRZ 400E - the off road model. It's liquid cooled; two radiators but no thermostat or fan.

The DRZ is a dry-sump engine, with the front frame member as the reservoir. No coolant temp gauge or light; no oil-pressure or temp indicators, either. On the trails, these things get HOT. My son has one, also, and it was boiling over when he got stuck behind an inexperienced trail rider on a too-big bike. Once he got ahead of pokey, enough air moved through the radiators to cool it down.

I sort of look at the oil condition when I check the level. As log as it isn't burned, dark and stinky, all is - to me - OK. Change it frequently and go. It takes 2 quarts, so $10-12 for good quality stuff a couple times a season and I'm good.

Does the oil get hot? Probably. How hot? Don't know; don't worry. As long as it's hot enough to boil off the water, I'm satisfied. Too cold is worse than too hot.

jb

[drewtam]

It takes about 1 psi to lift oil three feet, 1 psi can lift water 2.31 feet.

Oil pumps can feed multiple paths in parallel because a lot of the resistance to flow is at the ends of the path. This naturally balances the flow to about what the engineers want it to be. In ground lawn sprinklers work on the principle. Edit: I guess you are referring to the dry sump, I will go look that up.  http://www.honda-xr650r.com/tag/oil-pump/ has an oil diagram, I am guessing that the oil cooled models are similar.

Another idea for temp control could be to block airflow to the cooler on the highway if you are riding on a cold day.

My 2002 XR400 has an oil cooler, I have never worried about the issue whether it was 100+ or about 0F. The only difference is I make sure the engine is fully instead of mostly warmed up when it is cold out. I have heard of many people riding their dirt bikes in well below freezing weather without issue.

Cool a schematic.

Looks like there is pumps stacked on each other. One pulls from the sump up to the resevoir. That gravity feeds to the second pump that which feeds the filter and then to the whole system.

If the oil cooled is between pump 1 and the reservoir, there are likely no pressure drop issues at all.