Oil cooling for AVL engined Royal Enfield Bullet Motorcycle

Notice the oil cooler just in front of the crank case

Notice the intake lines and brass connectors to the oil cooler

Effective cooling is a must for all internal combustion engines. Before we move ahead and talk about oil cooling for motorcycles, let us first understand why an engine needs cooling. An engine needs to keep the temperature in check to deliver optimum performance. An overheated engine can cause damaged/seized pistons, dramatically increased engine wear and large drops of engine performance and engine life.

So, engines need cooling at all times right from start to stop and in some cases even after the engine is stopped or turned off. The Indian motorcycle market consists primarily of air cooled motorcycles. What does air cooling mean? Air cooling is a way in which the air in the external atmosphere is used to effectively cool the engine.

Along with the air, air cooled engines also use the air fuel mixture and the engine oil to keep engine temperatures under check. This is also a reason why a richer air fuel mixture is always advisable since the air fuel mixture is a major component of cooling the engine head and piston crown. Also synthetic oils have a higher flash point and thus tolerate heat better than mineral oils which makes them an ideal cooling mechanism for all kinds of engines, more so in air cooled ones.

Now, lets talk bullets. The Royal Enfield Bullets come in three engine variants, the Cast Ironed Engines, the AVL Lean burn engines and the latest Unit Construction(UCE) engines. The entire range of bullets have engine capacities ranging from 346cc to 499cc in an air cooled, single cylinder arrangement. This makes the Bullets one of the highest displacement Indian motorcycles.

Consider a scenario where you and your bullet are stuck in heavy, slow moving traffic. Like we discussed earlier, air cooled engines primarily use air to keep temperatures at safe levels. Slow moving traffic automatically means that the the air flow is reduced dramatically resulting the engine facing the prospect of receiving enough air to cool down. This causes the engine temperatures to go through the roof. The result will obviously be a an overheated engine and accelerated engine wear, not to mention fried thighs and ankles.

This problem, as we mentioned earlier can usually be tackled in three ways. One by riding in relatively traffic free conditions which isn’t really a viable option considering the traffic conditions in our cities. The second option would be to ride with a rich mixture. This, while keeping things cooler causes plenty of undesirable effects like hard starting, bogged down performance, fouled plugs and stalling. The third option would be running a synthetic oil. This doesn’t really have any drawback apart from the high, almost double pricing that it comes with. If you can afford it, go for synthetic oils as it can tolerate higher temperatures and perform better in all conditions without breaking down under stressful conditions unlike conventional mineral oils.

The fourth option, or the primary subject of our discussion is oil cooling. Oil cooling will essentially keep the engine oil, and thus your engine cool. This happens through an external heat sink/oil cooler that is fitted on to the motorcycle. The oil cooler will be inputted hot oil from the oil pump and will output cooler oil to the head through the oil lines/hoses. This will cool the oil and naturally leave you with a better performing engine that will last, keeping all other things constant, up to 40-50% longer than non oil cooled engines under similar operating conditions.

Now, we have a pre-fabricated, plug and play oil cooler for the AVL bullets. This oil cooler has been designed by ace bullet tuner, Chinmay Dangre of Pune, India. This oil cooler comes as a kit and can be bolted on to your existing set up. The kit includes the temperature resistant hoses and the brass connectors. As this oil cooler features a capacity of less than 200 ml, more oil can get recirculated and cooled without putting undue stress on the engine’s stock oil pump. Right now, field trials for the temperature gains are on and we’ll publish the data shortly.

The oil cooler kit will cost about INR 2,500 to 3,000 and will fit all models of the Royal Enfield AVL lean burn engines. These include the Thunderbird LB 350, the Machismo LB350 and LB500 models. Chinmay is also working out an oil cooling solution for the Cast Iron engines, which have a weaker oil pump than the AVL engines. This necessitates a smaller pump that makes sure that the oil cooler doesn’t put any significant load on the stock oil pump. Chinmay is currently developing a solution for this and it should be up and working shortly. To buy the oil pump or for queries, please feel free to contact Chinmay Dangre on 09822212496 or at macasp@gmail.com. People in Bangalore can get in touch with the author, Jay Prashanth at jayprashanth@gmail.com for orders and fitments.

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