I would say all the extra Kury engine cover stuff would trap more heat.

They only way to to tell would be to do some before and after heat tests.

 

Easily ?? Coming from the only guy since 1903 to turn a Street Glide into a Road Glide - anything is easy! I think I'm gonna cheat and get the cover. Don't be disappointed in me RedBeard!

Truth is, I'm running out of things to do. I would like to stretch the bags, but that's more $$ than I wanna spend.

 

I've had real chrome primaries and I've had primary covers. I have experienced no discernible difference between the two regarding my perceptions of engine heat.

I've had oil temp gauges on two ultras...one ultra (2004, 95" kit) with a real chrome primary...one with a primary cover (current bike)...no significant difference that I can really see, feel, or notice on the oil temp gauge or the dipstick digital thermometer that was/is present on both bikes. I also had a primary cover on my 2000 RK with no heat issues that I remember.

But I will say this... that primary side does get really hot through conduction as engine run time increases. Couple with that the frictional elements inside the primary and it's for this reason that a primary lubricant with high-temperature tolerances be used in the primary.

 

Ok Joe,

So you are saying as I keep using my Mobile V-Twin Synthetic in my primary, I should be good? I'm sure the $130 cover is cheaper than a real chrome inner primary - but it's really not as much cost as it is flat out lazy for me. Could I change it?? I think so, I wrench quite a bit on my bike.... but every morning I wake up, I notice I'm a tad lazier than I was the day before.

 

High temperature tolerance for oil translates into a 20W60 instead of a 15W40. You're looking for a slightly higher viscosity rating at 100 deg Celsius. If you're happy with your oil you may not live long enough to see any difference with another quality brand.

 

I've never used the Mobile VTwin synthetic products, but if they are working for you and have a heat tolerance of upward to 400F, then you should be good (assuming they have little to no friction modifiers so clutch operation will be normal).

If I had to remove the inner primary for bearing, pulley, or other work, I might consider replacing the inner with a chromed inner if I had the extra cash. But I am getting lazy myself and I doubt I would ever again change to a chrome primary just for the chrome aspects....that's why I decided to go with a cover. Cheaper, quicker, removable, and replaceable and at the end of the day, looks just as nice or nicer because the surface lines and attributes of the cover are better looking than that of a flat chrome primary IMHO.

Here's a shot of my current inner primary cover:

 

I haven't done any experiments but common sense says that the motor will take longer to cool down with chrome installed. Will it make any difference at all? Probably not.

 

Thanks for all the input guys.....

Joe- great looking pic, and great lookin bike.... I thought I spotted some dirt on your bike in the pic, but my monitor was dirty!!! That thing is shiny!

 

Thanks, but it has plenty of dirt on it from time to time. That photo was taken during one of the fairly clean moments.

 

There are three modes of heat transfer. They are conduction, convection and radiation. An air cooled engines main mode of cooling is convection. Your engine hopefully does not come in contact with any other body or mass so conduction is out of the question. That leaves radiation. A materials relative ability of its surface to emit energy by radiation is called emissivity. Just like flat black objects absorb more radiant heat from say the sun. A flat black body will also emit more radiant energy or heat. Thats why wood stoves and solar water heaters are back. On the contrary, shiny reflective surfaces are very poor at absorbing and emitting radiant energy. So while air is rushing buy your engine it is convective cooling,. The greater the duration and volume of air the greater the sum of exchange. The greater the temperature differential the greater the rate of exchange. Radiant cooling is only affected buy the surfaces ability to emit heat waves, therefore black bike components will cool quicker than chrome, all else being equal. BUT the same holds true for absorption, black components will also absorb a greater sum of solar radiation at a greater rate than chrome. Stay out of the sun and drive into the wind and you will have no problems right.