Twin Cam 96 engines operate at higher temperatures than the Twin Cam 88 engines, in part because the TC96 has almost 10 percent more displacement, but also because the new engine is calibrated to run a leaner fuel mixture to meet exhaust emission standards.

At some engine speeds this lean mixture produces more engine heat. Harley-Davidson has a dealer-installed software upgrade called the Engine Idle Temperature Management System (EITMS). During hot idle and only when the motorcycle is stationary, EITMS shuts off fuel to the rear cylinder to allow it to cool down rapidly. When the cylinder cools or the motorcycle moves, normal operation resumes and the transition is seamless from the rider’s perspective.

Bert Baker, aka The Tranny Guy, looked at the problem from a different view point. Why not, he reasoned, keep the engine cooler in the first place? Thus from the fertile mind of this Michigan-based engineering wunderkind came the Baker Plus One oil pan, so named because it increases pan capacity by one quart (.94 liter).

Baker Drivetrain (www.bakerdrivetrain.com) claim the Plus One pan will reduce engine oil temperature by 10 degrees Fahrenheit on an 80 degree Fahrenheit day. But that’s not all. Whereas the feed and return on a stock pan are located within two inches of each other in the front of the pan, the Baker pan has the feed located in the rear, and the return in the front, for a more complete system circulation.

It also incorporates multiple integral aluminium baffles to eliminate the stock plastic baffle. And, as a bonus, it includes an integral boss for either the Alloy Art TXR stabiliser or the True Track stabiliser. The Baker Plus One is available in either a one piece cast unit or a two piece billet one.

We recently installed and tested a Plus One on a 103- cube 2004 FLHTCSE with impressive results. No, it’s not a TC96, but on the basis that displacement causes heat increases (bigger burn=more heat) I figured it would be a very fair comparison, an even tougher test.

It should be noted that all testing was carried out with the fairing lowers in place and with them in the closed position, plus the Kuryakyn Dragon Wings (H-D version is called the Adjustable Air Deflector Kit) also in the closed position.

I figured that an 80-degree day, as quoted by Baker, isn’t all that hot. I discovered it’s on the high side of 85-95 degrees that my 103-cube donk becomes hot and uncomfortable, so I waited for a day when the temperature was forecast to hit 95 degrees, and I rolled over to Hyperformance Cycles/SA Chopper workshop mid-morning where Harley tech Ben carried out the installation of the Baker Plus One and I road tested the results.

The first step was to drain the old oil and refill with a fresh batch of Mobil 1 V-Twin. Then I waited, drinking coffee and pacing up and down while watching the weather bureau web site to monitor the temperature. Once it reached 95 degrees I took off on a base line run, firstly peeling through a 12-mile circuit on suburban roads and then heading up the interstate where the speed limit increases. There was a 12-mph hot wind blowing, creating a head wind for the first stage of the test. I took readings at several speeds; 45, 55 and 70mph, and then monitored the same speed runs and readings in the opposite direction. I also took readings at idle at the traffic lights on the way back to the workshop.

Once back in the shop, with a fan blowing, to rapidly cool the motor down, the task of removing the stock oil pan began.

He bolted it in place with a series of long fasteners, which is where we hit a minor snag. On this bike the frame cross- member blocked access to one of the bolts. How could this be? They came out okay.

Whereas the Harley pan is held on by bolts around the rim the Baker Plus One uses longer bolts, which go right through the edge of the pan.

With me pacing up and down, stressing about whether the outside temperature will change, Andy and Ben whipped the Plus One off again and Andy drilled the existing frame cross member hole out to a half inch diameter to allow placing into position and tightening that particular bolt.

Fortunately it’s a task quickly accomplished and that bolt, along with the rest is replaced and tightened and the old oil is put back in (as I don’t want any variables), and the extra .94L is added. (Though in Yank-speak that would be a quart)

Thanks to the Dakota Digital gauges (engine temperature lower left), ascertaining the exact temperature was extremely easy. After checking the weather bureau, the temperature was still holding at 95 degrees. I headed out to repeat the whole exercise, riding the exact route as earlier. The results were impressive. If any variables come into the picture it would be that the road temperature would have increased over the time it took to swap oil pans making the difference even more impressive.

Stock oil pan at 45 mph--172F
Baker Plus-One Oil Pan--164F

Stock Oil Pan at 55 mph--170F
Baker Plus-One Oil Pan--160F

Stock Oil Pan at 70 mph--166F
Baker Plus-One Oil Pan--157

Stock Oil Pan at idle--172F
Baker Plus-One Oil Pan--154F

Apart from the benefits of the Plus One in terms of oil life and engine wear reduced with a cooler running motor, rider and pillion comfort is also enhanced. Ten degrees makes a noticeable rider comfort enhancement. This modification is highly recommended. Baker products are available through most dealerships and aftermarket stores or visit Baker Drivetrain at http://www.bakerdrivetrain.com for more information.