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Discussion Starter · #1 ·
For reference, I'm currently running a CJR tune for a MNNTHBX intake, Supertrapp exhaust, and TB cam. With 14/36 gearing, it's great and has enough power for most situations. I say "most" as a significant incline will drop my top speed significantly, and a bunch of my fun riding is in the mountains where I see a lot of hills, sometimes on 55mph zones where I cannot even maintain the speed limit. I know with great power comes great... heat, so I've already upgraded to the Takegawa high flow oil pump, and I'm monitoring my oil temps at the drain plug via a Takegawa tach/temp meter.

With air temps in the mid 80s, I generally see oil temps from 90-110C (194-230F) but today the ambient temperature was approaching 90, and I was really flogging the bike on the highway for a good 15-20 minutes at WOT. I eventually pegged the oil temp gauge at 120C (250F) so I'm not sure what my actual highest oil temp was. I'm thinking it wasn't too much higher as the oil temp started to drop shortly after I got off the highway and slowed down. I run Rotella T6 oil.

A couple things I'm not sure about:
  1. How much different/higher is the oil temp elsewhere in the motor from the temp reading at the drain plug?
  2. Any cause for concern at current readings? I've read T6 is good for 300F.
  3. Would a HC piston be a bad idea without an oil cooler given these current temps?
I really don't want to install an oil cooler for the HC piston, so if one is required I'll probably stick with my current mods and go on a diet.
 

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a lot of good question. If anyone can shed some light I’d be interested to know about question 1 also
 

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Discussion Starter · #3 ·
I emailed CJR and received this response. I don't think it's really private, just good advice about running a HC piston. I think I will hold off and just enjoy the bike as is for now.

Generally we see oil temps in the 230-250f range, 260 getting on the higher side. These air cooled engines naturally run pretty hot and an oil cooler is never a bad idea. A lot depends on riding conditions, slow around town riding can build up a lot of heat as the engine is not getting passing air while wide open riding does receive good passing air however under a heavy engine load. We haven't really had any issues on the high comp piston with heat unless there's an underlying issue or oil starvation. Let me know if you have any other questions!
 

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Discussion Starter · #4 ·
Some other details regarding temperature. I checked my oil and I was looow! Maybe by as much as half a quart which is huge. I added a bunch and will monitor consumption. Temperatures already seem lower, but I have not really put the bike through its paces on a hot day. Might have a hot one this weekend or early this week, so I will see if I can peg the needle again.
 

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If you can't stay under 100°c temp on cylinder it's better to install a cooler dude....

Oils start to rise white flag at that temp
 

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Discussion Starter · #6 ·
I'm not concerned with 100C. That's only 212F and well below the threshold for synthetic oil which is closer to 150C. In fact, you'd want to get oil temperature over 100C to boil off any moisture accumulated in the system.

The problem is not knowing how much above 120C I was on that run, and what oil temperatures are when observed elsewhere in the engine.
 

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Discussion Starter · #7 ·
The oil level has certainly helped. While I haven't given the bike the same stress test, I did ride for about 50 minutes with the temps in the upper 80s. A few miles towards the end I was really trying to wring its neck, and I was finally able to get to 106C while moving. It's possible the temps would continue to climb at that load, but I ran out of runway so to speak. As I slowed down they jumped up to 111 and then gradually started to drop again as I slowed to a 30-40 mph cruise.

I'd say this is a much more comfortable temperature, though I'm also curious to know how much higher the temps will be with the HC piston. Most of my riding would be at slightly lower temperatures.
 

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I as do MANY others, live in Florida (just north of HELL) and run the DHM HC piston with great success. I have a different kind of build going on, my bike is almost like a 2 stroke the way it hits the power, and revs up to 13k! People may get me off the line, but once it get above 8-9k I will cruise on by...... Hell, David lives here too, and that piston is his baby. Tune needs to be adjusted accordingly, and the plug he sells for the piston kit should be used as well.. :cool:
 

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What oil temperatures do you see? And are you running an oil cooler?
No oil cooler and no temp gauge (low budget build). I felt it getting weak when I 1st installed the piston after break in, at higher speeds, notice my 02 gauge reading 16-18!!!!! I installed a 120cc injector to try and keep up with my RPM and retuned, whole different bike now. Still a little lean up top, need to spend some more time cleaning 10k+ up..... Getting way better though. My buddy is getting pissed he spent so much on his 181 build and I leave him all the time :cool::cool:
 
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