Discussion Approved

isn't it obvious? a 1950's design vs a 1990's design. Enfield has a primitive engine , as simple as that. There are huge losses in the power output too.

There's a lot more to this debate/discussion than just the way the engines are built. Let's get the Bullet lovers on board shall we?

bulleteers believe in bull power while others believe in horse power....simple as that.....

The old push rod engine of the bullet ( either the cast iron or AVL), barring the new twin spark engine, runs on a very old basic design.

To compare, there are a number of major differences between a bullet's engine and a normal everyday bike engine.

1) design of cam- the bullet has a dated, push-rod type design, which basically places the cam ( that operates the valves of the engine), on the side, running right off the engine crankshaft, mated to it by gears ( Timing gears , which is a combo gear + cam).

The cam pushes a rod, ( hence push-rod engine), which further moves a rocker ( something like a see-saw), which presses the valve. Whew!

In the new engines, the cam is a long shaft on the top of the head of the bike, running off the engine by a chain and gear mechanism, with a auto tensioner in the chain, so that there is lil or no slack. The cam directly presses against the valve, reducing the number of moving parts, and the transfer of to-fro motion of the cam is direct to the valve, rather than going to the push-rod, then to the rocker, and then to the valve ( eliminating a lot of friction in the process, and improving the efficiency of the engine).

Also the need of a push rod engine is constant adjustment and checking of clearance of the tappets/pushrods etc. Because of so many parts, and their differential expansion when the engine warms up, this play has to be kept adjusted and kept to a minimum.

Thats the basic first one. Next up, the engine bore and stroke, the bullets have a long stroke engine ( also called under square), which make terrific pulling power at low rpm. Which the bullet is popular for.

This was more in need with the bikes of yesteryears, when a decent amount of emphasis was given on low end torque and pulling power.

Where the bullet makes "only"18 bhp from a 350cc, it makes up with oodles of torque at 2.75 kgm, compared to about 1.9-2 for the P220 iirc.

2) Primary drive and primary gear - The gearbox in the Bullet is a separate section, and so is the clutch assembly. The power from the crank is transferred to the clutch, using a chain ( also called primary drive). In todays bikes ( actually in nearly any other bike), this is done with the help of helical gears ( Basically normal gears, which have their teeth at an angle for better meshing and lesser free play between the gears ). THis further reduces power losses, reducing friction, lowering free play, and reducing one more item that needs adjustment.

Generally the primary drive of a bullet must be checked for the correct tension at every service.

3) Independent oil chambers - The bullet runs separate oil chambers for all its components. The engine has its own chamber, and filter and pump. The gear box has its own grade of oil ( or grease in case of CI engine) to be used. And the clutch case uses its own oil.

So you could be running synthetic oil in the engine, but the clutch would be happiest running in regular everyday grade oil. And the volume of total oil is a lot. 1.9 litres for the engine, about 600-800 in the clutchcase, and another 600-750 in the gear box.

So there are so many things to be taken care of!!

In the new engines, everything runs in the same oil, the clutch, the gears, and the engine. Making it more compact/lightweight and lowering the amount of oil needed etc.

4) Basic design gap. The Bullet engine is virtually unchanged for the 60-70 years. Whereas new developments keep coming in the regular market. This is what also gives it the old world charm.


hope this clears some things up.

Nicely put JD. My 350cc Royal Enfield Electra puts out 18 bhp at 32NM of torque, while the Kawasaki Ninja gives 33 bhp at only 22NM of torque. That's like 50% lesser than the RE in spite of being much higher in bhp output!

Cc for cc, cruiser motorcycles (HD included) will give much greater torque at lower RPM/BHP as compared to higher bhp/high RPM/ low torque for sportsbikes. Kind of a comparo between a sportscar and a heavy duty truck, where the bhp of the truck might be lower than a sportscar, but when it comes to pulling power, the truck will demolish the car.

Very nicely put JD...

The most significant loss in power is due to the engine being long stroke, meaning that the bore is lesser that the stroke. In Electra, it is 70mm X 90 mm. Some negative points of this arrangement are greater cylinder wall friction and lower redline. The positive aspect is you can cruise at a lower RPM and more low end torque. Check this link for more info on Bore/Stroke ratio. Compare the Electra's B/S ratio with Classic 350's, and then their power and torque figures and the RPM they come at.

The other factor that brings down the power comes in the form of the gearbox and clutch being separate from the engine. All that power transmission losses due to friction has to be accounted for. The current breed of UCE engines has the gearbox incorporated into crankcase to lower the friction losses.

^^ thanks for the appreciation guys!! mean it

ummm!!!!!!!!!

Good work JD....


well it is not primitive if u try to compare with 80 's engine. At that time and stage it was the finest design from Royal Enfield, just like BSA, Triumph etc...etc..Oh yes it is primitive if u compare it with new engines like pulsar's, apache and all.....

Basically bull is LOW RPM HIGH TORQUE engine and others are High RPM low torque engines...
this is under square engine and others are either square or over square engines....
Under square engine = Stroke is higher than bore
Square = stroke and bore is the same.
Over sqaure = Bore is higher than stroke.

Well this is low RPM coz this has huge crank diameter compare to other bikes.
Oh yes and this is OHV but not SOHC or DOHC system.

Due to it's heavy torque the bike can go in 4th or 5th gear at low RPM but others fails to achive that...The BHP of a engine depends on many factors.....the way ninja produce the BHP can't be comparable with Bull's.

Can't compare whether the motor, clutch and Gear box is separate coz now they have UCE too....but that will not define whether the engine is high or low torque.....

so comparing this bike with others not possible for 1 simple reason, bull is high torque low RPM engine and other's are not...

and main factor is, u can open bull's engine "N" number of times and nothing will happen to the engine...it will still work coz there is no issue of any leakage coz bull is already leakage pron engine....but others, well once it gets open then many engine shows the oil or leaky parts....hehehehehe<< this is the major comparo which I should admit...

Very nice JD!!

nice topic. . .even i was searching the same stuff on google ....nice

Very simple explanation (mechnically)to this is that the stroke in cruisers are usually longer as in the case of a bullet and shorter in the case of sporty bikes. Longer the stroke, more time it takes to complete a full power stroke even though the displacement is high. Since the final horse power is indirectly related to the stroke and bore dimensions. It's always been like this longer stroke engines have good Torque while the shorter ones have good Bhp. But if u are a smart and a good rider u can challenge the sport bikes with the extra torque u have in ur cruiser!!!!!!

Difference-> Bullet vs other Bikes

Now RE had come up with single compartment for Oil in UCE. Also, twin spark plugs for engine. I think in other terms too, RE is coming to current standards.

Still it remains High Torque Low RPM machine. On high RPM, it is like other bikes. But what keeps Bullet different from other machines (non-technically) is low gear shifts and mile's cruncher machine.

Very less fiber and no heavy damages on falls and rough roads. Good to control and excellent riding. Excellent information, groups, maintainable and do-it-yourself attitude.

Hope this helps in differentiating.

Jay,
What about its heavy weight? Do you know, riding a normal 150cc Indian bike over bad roads and riding a Bullet over bad roads is a world of difference? With due respect to Enfields, the bike has improved over the years, but there is a lot to do when it comes to catching up with other bikes. My 2 cents