Service Letters

SERVICE LETTERS

KEEPING IT COOL

I am considering putting an oil cooler on my 650 Yamaha and would appreciate answers to the following questions. First, are they a worthwhile item on a road machine and by how much do they drop oil temperatures on a warm summer day? Second, how much cooling can be expected with the dipstick-type cooler presently on the market?

Third, is there any danger of engine seizure due to long idling, slow speed traffic conditions? Fourth, would a paper-type element oil filter be more efficient than the present wire-mesh type on the machine?

G. DeVito E. Islip, N.Y.

It is practically impossible to install a separate oil cooler on your Yamaha XS-1. To do so would require extensive welding and machining of the crankcases and would require dismantling the engine completely.

The simplest method of equipping your machine with an oil cooler is to use an Isocycle Oil Cooling Dipstick, available from Megasonics, Inc., P.O. Box 87, Greenwich, CT 06830. The Isocycle works on a principle developed by NASA and the operation is very simple and foolproof.

It is composed of three basic components-a hollow container, a capillary or wick structure and a working fluid, which in this case is water. Before sealing the unit, all air and gas is evacuated. This is done to lower the boiling point of the water inside.

At a temperature of about 160 degrees the water inside the heat pipe begins to boil, causing it to ride up the capillary material and rise to the top of the unit which is a finned aluminum heat sink. Air moving past the heat sink causes the steam to condense back into water and fall to the bottom of the pipe, starting the process again.

Isothermics Incorporated, the Isocycle’s manufacturer, claims a typical reduction in the engine’s oil temperature of from 15 to 25 degrees, depending of course on the temperature of the oil, the outside air temperature and the amount of air flowing past the finned aluminum heat sink.

There is always a danger of engine overheating in slow moving summer traffic, but there is very little danger of seizing your Yamaha when traveling under these conditions, especially with an Isocycle Oil Cooling Dipstick and the proper grade of oil in the engine.

A paper oil filter element is more efficient than the wire type because it can trap much smaller particles which circulate through the engine. But changing the engine oil and cleaning the wire oil filter at the prescribed intervals will assure long engine life without undue wear of internal parts.