Kirby Rowbotham Technical Engineer

Proper Oil Filtration For Triumph Twins

The oil filtration on most British motorcycles is somewhat crude when judged against modern standards. In defence of the industry it must be said that at the time of peak popularity not many machines were covering more than 15000 miles per annum. Engine rebuilds were required at much shorter intervals than we would expect today. Engine rebuilds would have been relatively inexpensive when compared to today’s prices.

Classic bike riders nowadays tend to cover less mileage and use their machines infrequently. The importance of oil filtration becomes more pertinent. Clean fresh lubricant is the lifeblood of any engine. The complete restoration of a classic bike is not cheap and it is not easy. With much money and time invested in the machine it seems only sensible to protect that investment in the best way possible.

Triumph motorcycles are very popular classic bikes. The oil filtration kit explained below is for Triumphs only. Other makes may lend themselves to a similar system.

The fitting of a filter to the oil return line is not recommended. When designing this filter system the technical departments of filter manufacturers were consulted. Not one was happy with a filter in the return line. It is preferable to feed paper element filters with a constant flow of oil. The intermittent flow in the return line from a dry sump lubrication system may cause a local breakdown of the filter material and allow debris to pass through. The increased pressure in the return line may cause the residual oil level in the crankcases to rise; this may in turn induce oil leakage from the crankcase breather. The oil has already passed through the engine; any particles in the oil may have damaged the engine before the oil reaches the filter.

Having stated these negatives it must be said that some sort of filtration is better than none at all.

A pressure side filtration system is the best solution. Consider all modern automotive applications and you will find that the oil is filtered on the pressure side of the system.

We, as fans of Triumph motorcycles, did not like the lack of proper oil filtration. When rebuilding an engine we are appalled at the amount of engine detritus always found in the sludge trap of the crankshaft. Something had to be done, so we designed and developed a system that would filter the oil before it entered the engine. The oil must be filtered under pressure, so the filter must be placed between the oil pump and the engine. The filter must not be fitted between the oil tank and the engine.

We modify the timing cover to force the oil out under pressure to a remotely mounted filter. The oil then returns to the front of the timing cover and into the engine. When rebuilding engines fitted with this filter system less than a quarter of a teaspoon full of sludge has been found in the sludge trap. These engines had covered a considerable mileage, one in excess of 70,000 miles.

We now make the filter mounting plates frame type specific; One for oil in frame and one for pre oil in frame. Specials for rigid frames and Tritons can be catered for.

Triumphs fitted with oil pressure switches are supplied with filter plates machined to accept the switch.

A competent mechanic, amateur or professional must fit this kit.

Designed, developed and manufactured by ourselves.

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