Hi,

Bike is running great, about 40mpg, 94 FXSTC with a crane CV3 cam, carb is jetted 45/165 with thunderslide & thunderjet, huge aircleaner, Python drags with Kromewerks baffles and lollypops. Probably running a little rich in the low range but I need that to minimize the decel pop from those pipes. No black smoke, plugs look really good, bike idles excellant after short warmup and it's set to idle slow.

Ok, I've got tinkeritis, so I'm asking the only thing bothering me...

So, how come my bike runs so cold? On the hottest summer day it might reach 185 but 175-180 is normal, in this weather I have to run it hard 30+ miles to even touch 160 and around town it stays @150-5. This is the first bike that I've had an oil temp guage and it's accurate-I checked it against known good thermometers. Are these temperatures normal? Sounds low to me.

Thanks
Doug

 

What engine oil do you use ? 20-50 regular HD oil or synthetic type Syn runs cooler than reg oil

 

I would just count my blessings! Most of us have the EXACT opposite problem and ours is terrible for the motor...

 

be thankful. i have a 1990 fxstc and also run cool. im here in arizona and run same temps. even when its 90 - 100 outside ill run under 190, i do have a factory oil cooler with a thermostat. ive seen a lot of post about bikes running above 200 - 220. even if i sit at a light in 95 degree temps i wont get above 180 degrees. and like you i have the oil temp dipstick and have also checked it with a inferred gauge and there within a couple of degrees.

 

My 99 FXSTC is the same. Takes a long time to get it warm, and still runs cool. I run Mobil 1-Vtwin 20-50 syn., and about 6 oz. of Prolong. I thought it was probably the Prolong that was making it run cooler, as it makes everyting I run it in cooler. I ran Prolong in my old Iron Sporty, and it did not do the tic tic tic thing anymore after a hard ride when cooling off. In cool weather, I generally let mine warm up for about 5 minutes before riding, and then take it easy for a couple of miles. So far no leaks.

 

One thing is that around town, even in hotter weather and unless you're bogged in beach-type traffic, it'll always show cooler. Why? because the oil stays in the tank longer and not circulating as fast as during normal - higher speeds. Oil cools rather quickly when it's in the tank - usually.

On the other hand, if anyone reads this who has an FLH or T, the oil in the tank will actually rise in temps during easy riding. I thought my temp gauge was wrong after doing a rebuild some time back. I bought a dipstick-type thermometer and it showed 50 degrees more than the gauge so I used a resistor and corrected the gauge. Recently, I was checking my oil cooler with an infrared thermometer and saw the oil coming from the engine was actually 50 degrees cooler than what was in the tank. And the oil in the bottom of the tank was cool. That had me bluffed... I checked all along the system (cooler, filter, lines, ect.) and verified that the oil in the center and upper portion of the tank was a lot hotter than in the bottom (where the temp sender is).

So apparently when moving at moderate or higher speeds, the heat from the engine warms the oil in the tank, especially on the 4 quart Dresser tanks and I'd imagine it does the same on the horseshoe type to some degree. So, after all that I have come to wonder about dipstick temp gauges. Certainly a good thing for reference but I have to think not the bottom line as to exactly what the oil/engine temps are doing.

If I wanted I could easily plumb a large pipe tee on the "in" and "out" and rig up electric gauges to get down to the gnats azz, but why bother... I've posted and said many times that generally they should run 100 degrees over ambient, but mine is way cooler than that and to HotRod and Doug, I figure your stuff is "right" being the reason for the lowered temps. Bottom end bearings and bushings are what generate the most heat as far as the oil temps are concerned. Lean jetting doesn't necessarily jack up the oil temp, just causes combustion chamber/cylinder problems. Oil does take some heat from the heads but not that much compared to the bottom end.

PS. you can't use an infrared thermometer on anything chrome - it reflects the beam wacky and gives a false reading. But, you can mark a spot black with magic marker (that will polish right off) and get a better reading on a chrome oil tank, nosecone, primary, etc.

 

Thanks, I wasn't worried, just wondering. I too have read the posts about high temps, oil coolers and such. I use Castrol dino 20-50 and change it every 3K. Just got back from a 2 hour ride, I'm not changing anything...Ride safe

Doug

 

Jim,

What is ProLong?

Doug

 

It is an oil additive. They use to advertize it on TV alot. They ran engines on it, and then drained the oil, then fired them up, and had race car drivers run them around the track for hours at racing speeds with no oil. Anyway, I have been using it in everything I have for the last 10 years. When I put it in my 84 Sportser, it quieted it down a bunch, plus running way cooler. I put it in my lawn tractor, and it went from pulling down in tall grass, to going through it without opening the governor. I also run it in both of my Dodge vans. My 99 has 115,000 on it, without touching it. I only add about 6 oz. when I change oil in my 99 Softail. My old EVO runs very quiet, and very cool. Also runs better. I do use Mobil-1 VTwin 20-50 also. Prolong is available at Auto Zone. I know this sounds like a commercial, but it's not. I am just sold on it.

 

Isn't there some thing being uncovered in the media about Prolong being nothing more than mineral oil?? (Babyoil)???