There are mixed opinions on this matter, for example if you asked a local mechanic or someone who owns an Enfield from 2008 or before, he would definitely tell you that the older version is better. However if you walked into a showroom or asked an Engineer, they would tell you that the newer version is far better. Let’s take a look at what are the major differences in these two builds of the oldest and still in production motorcycle of the world.
The newer version consists of a Unit Construction Engine, UCE, while the older ones were a cast Iron Engine. Here’s a quick comparison if you really want to understand more about the intricacies of the different Royal engines.
First a quick look at what UCE is all about. Earlier Enfields, both the cast Iron Engines and the AVL LB Engines used to come with a pre-construction unit which actually was three parts, the engine, gearbox and clutch cases, put together and connected to each other independently.
Biggest drawback of this was a heavy maintenance because you were required to change oil at all three places each time and also added was the cost of the gaskets that required replacement frequently. Another setback of this engine was loss of power in transmission as the setup was not as efficient as modern engines. This loss of power was as high as 33% between the crank shaft and the rear wheel. For example, The cast iron and AVL engines were capable of producing 18 BHP at the crank but due to loss of power in transmission, this figure would go down to 12 BHP at the rear wheel.
Another result of this loss of power was lesser mileage. UCE engines on the other hand produce 19.8 BHP at the crank and the power is 16 BHP at the rear wheel, hence the loss of power during transmission is close to 20%. This figure is of course still high but okay when it comes to a Royal Enfield. While the CI and AVL engines could only deliver 30-35 kms per liter, UCE could consistently return up to 45 kmpl.
To get into a bit further into the nitty gritties of these engines, the UCE engine uses Hydraulic valve lifters so what happens because of this is that pressurized oil drives the pushrods in the engine. When the oil pressure remains constant for longer periods of time, the pushrods don’t cause the valve clearances to change like they used to in the older engines resulting in consistent performance. In simple words, riding hard won’t make your valves loose as frequently as it would happen in CI and AVL engines. The hydraulic tappets in UCE would stand at least 18,000 – 20,000 kms before needing any kind of attention while the solid tappets in CI and AVL would often come lose and would require adjustment.
Another big change with the UCE is of the oil circulation. On the cast Iron engines, which actually were designed in 1950S, piston type oil pumps were used. These oil pumps circulated about 1 liter of oil per minute at 5,500 RPM which is almost half of the Bullet’s oil capacity. So at 5,500 RPM, when the engine is reviving at its very top, just 1 liter of oil was circulating to cool down the engine which can only be termed as “bad engine cooling”. This is the very reason why the older Bullets were never considered for riding hard and fast but more as a steady 60 kmph motorcycle. Anyone who owns an older Bullet would know that you cannot push this motorcycle beyond 80-90 and keep at that speed for a longer period of time. You probably would not even dare to take it beyond 100 kmph. The heavy crank engines came with a floating bush big end which could only work well as long as it was immersed in oil and there was enough flow but 1 liter of oil per minute at the top was just not enough. This speed of 50-60 kmph which today can be considered as low was decent enough in 1950s but not anymore. Then in the 90s, Enfield approached the Austrian engine design firm AVL to make amends to existing Cast Iron engine and the AVL engines were born. The biggest advantage of AVL over CI was of a better oil pump and a roller type big end bearing. These AVL engines, using a gear driven oil pump, were capable of pumping double the oil per minute than CI engine, 2.42 liters at 5,500 RPM as compared to 1 liter of CI engine, meaning better engine cooling. The roller end bearings work also better than the floating bush.
Despite these changes, AVL engines proved to be the least popular. AVL introduced an aluminum block, which while could dissipate the heat better, but was prone to valve train clatter as it muffled less sound. The thump of the Bullet was the very soul of this motorcycle and this is what the AVL engines killed. People were used to thumping on their bullets at 40-60 kmph all day and this caused the AVL engines to be less popular even though they were superior to cast Iron engines in every manner.
difference between a 2014 and a 2017 Royal Enfield Classic 350 – After AVL, Enfield introduced the UCE which is their most advanced engine so far. The UCE engine has improved valve train apart from a lot of other improvements. It is capable of pumping 9.5 liters of oil per minute. These engines have an anti-backlash system engineered into the cams, making sure that the cam backlash is kept to the bare minimum. This results in an increased cam life as well as maintaining consistent engine performance even under hard riding.
difference between a 2014 and a 2017 Royal Enfield Classic 350 – People who have owned CI Bullets would know how troublesome backlash can be on Cast Iron and AVL engine bullets, which though featuring adjustable cam spindles were still troublesome if ridden at speeds of 80 kmph and above frequently. Also, the UCE engine has a piston ring designs that eliminates blow by. A lower blow by means lesser oil getting wasted or lower cranks case pressures. Two more changes are an auto decompresses assembly that sits on the UCE engine’s exhaust cam that makes starting easier and an auto primary chain tensioner which makes sure that the primary chain has just enough tension to ensure best performance and least maintenance.
This being said, the biggest drawback remains to be the thump which is almost gone with the UCE engines so if you are planning to buy an Enfield anytime soon, decide what you really want. If you really want that thump of the engine so bad, are happy with thumping around the city at 40 kmph, do not plan to ride hard and fast then you may buy a CI or AVL but remember that the parts of both these will soon become scarce as UCE is definitely the future of Bullet. Royal Enfield themselves offer a 40,000 kilometer/two year warranty on the UCE bullets while they used to offer only 10,000 km/1 year warranty on the Cast iron and AVL engines.
If you have read it all so far, then you would know that the current UCE engines exceed the older CI and AVL engines in every aspect. This however does not change the fact that no matter which Enfield you chose, it still means power and durability. Both bikes are very capable and only the arguments of users are different. Vintage Bullets today sell at almost the same price as of a new one, no matter how old it may be. As a matter of fact, older the Bullet is, costlier it would be. Some of the other things to consider between the two models are,
1. Low stance of new classic model means better seating position for touring
2. New wide handles gives more control in traffic
3. The smoother shift gives effortless gear change
4. Engine embedded gearbox offers less maintenance
5. Fuel efficiency, self start, disc brakes, gas shocks, and switch qualities in newer models
Coming to the older versions,
6. The legendary Thump
7. The classic image of the right shift
8. Excellent stability and response up to a speed of 50 kmph
9. Better performance in high ranges and in heavy traffic conditions.
These are some of the facts that I just narrated here. I know that people may or may not agree with these and there will always be an argument regarding old and new Bullet. So decide and chose wisely. And yes, HAPPY THUMPING!!!!!!