Royal Enfield’s Upcoming Twin Cylinder Engine

Royal Enfield’s Upcoming Twin Cylinder Engine

Royal Enfield has been in the game for a long time now and it appears that they are finally working on a twin cylinder mill, which has been in rumours for sometime now. It is not only awaited in India but the world over! We have received a few queries from our international readers about the details and possible launch time frame of the twin cylinder motor, however, we just did not have any info. But only till now! The folks at Bikeportal have caught sight of a continental GT with an interestingly different looking engine!
The images show here a twin cylinder bulky motor fitted on the chassis of the compact Continental GT. A few pics of the surroundings also hint at the place to have some Royal Enfield connection. So, in all probability, it definitely appears to be THE engine we were waiting for! The displacement of the motor cannot be confirmed but according to speculations it is expected to be in the vicinity of 700-750cc. The engine is arranged in an in-line configuration fed by two large carburetors (no fuel injection?)!
The spy pictures also take our attention to the radiator which indicates that Royal Enfield may finally be moving to the liquid cooling systems, which we believe will enable this big motor to run cooler and offer better overall performance.

ROYAL ENFIELD BULLET 350cc REVIEW

ROYAL ENFIELD BULLET 350cc REVIEW 

The Bullet Standard, Electra, Classic are the cosmetic variants of the Bullet 350cc line up, with very minor technical differences between them. Hence performance and all aspects of these are almost the same with only some difference here and there.

Bullet Classic 350

THE REVIEW 

The Royal Enfield Classic 350 is my test machine ,I took it for a 150 Km ride through traffic, broken roads ,highways, mud and everything I could possibly find the bike to put under the test.

THE START

The engine comes life with just single press on the start switch , No kicks and starting problems .There is a fair amount of vibration on the bike which can be identified by looking at the rear view mirror shaking, The vibration vanish with slight twist to the throttle , the engine revs freely feels well engineered and refined.

LOOKS

The styling on the bike is really goes well with its geometry, very distinct and worth staring at silver paint job on the bike is of great quality everything looks perfect and in place. The overall size of the bike well suited for most of the rider. Tank is a piece of art , the rubber pads are well in place , the rear fender hugs the tire nicely. It is one of the best looking bike on sale

ENGINE

350 cc puts 19.6 bhp and 26 Nm of torque, all the power and torque are available at the low and mid rpm. The engine doesn’t like to be accelerated hard, gentle twisting of throttle the engine responds the best. BULL as enough punch to pull anything that sits on top of it , never really feels underpowered .

RIDE

Going uphill was a breeze 3 gear 40 km/hr the bike really did well, torque is constant throughout the rev range .  Bike is rock steady in most of the situation , at 90 kmhr on the highway bike confident and planted and grip on the road is superb. Going beyong 90 you will feel vibration from all parts of the bike coming to you , saying you to slowdown. It is not a racing machine it is meant of cruising at 70 to 80 kmhr.

Suspension has really improved , dynamically the bike feels better compared to the older ones , cuts through traffic well , steering is not heavy and turning radius is also reasonably short , city rides wont be a problems . there is bit of heat which can be felt on the legs while riding the bike though traffic. 1 and 2 gear pull the bike nicely through low speeds of 5 to 10 kmph, clutch is also not heavy to tire out your hands but definitely heavy compared to other bike. Gear ratio are well set for all riding conditions and  you will definitely find a perfect gear for a speed for your choice . shift are not that smooth, neutral finding is tricky at times. But RE show a good improvement in all the aspects of the bike .

Braking

One area which really needs improvement this is it. Stopping power seems in sufficient  , the front disk is also soft and doesn’t offer good feedback. Rear drum is something you cannot rely while heavy braking.

Fuel efficiency

Highway 38 kmpl

City 32 kmpl

Can improve if you ride well

Verdict

The Bullet is an Icon of Power and Masculinity in India , the bike keeps it up , well there are area of improvements but what it offers is exceptional that no other bike can. The feeling itself of seeing it makes you smile and history of over half a century passes through your mind just a glimpse of the bullet makes all this happen. The all metal construction will make bike last thorough generation in the family and a proud possession.

It is not great piece of engineering nor it is meant to be that, it is the connection between body and soul the joy and the pleasure it’s all about the feeling when you ride it. Buying one will really make you proud owner of the BULLET .

ROYAL ENFIELD MOTORCYCLE

ROYAL ENFIELD  BULLET AND THUNDERBIRD PROBLEMS

If you own a Royal Enfield then one of your best friends might be a mechanic , if you don't have make one.

Unlike a 100 cc bike that just demands petrol , and occasionally fancy oils . and that doesn't even care that you care for it or not . It demands nothing a does all that you want . just start the motor and head out .

A Royal Enfield might not be such a good buddy.You might have to pamper , love and cuddle the beast  to keep it running .Even after all that if not satisfied he might just refuse to move .It demands affection to pet a royal Enfield .

Whatever problems the bike throws at you the joy of solving those might make you an true   Royal Enfielder .

Royal Enfield maintenance

Bullet is very well known for its heavy maintenance requirement, frequent tune up and adjustments. Many issues regarding the quality and Manufacturing defects have been ignored by the company since a long time. Some area in the bike require serious improvements like the braking department. To stop a beast with such a mass and torque the front 280 mm disc and the rear drum seem to be in effective in providing sufficient stopping power. The wear and tear for the friction lining is quite frequent and doesn’t last for a good amount of time. A rear disc is badly needed in all the models as standard.

Another area where the Enfield needs improvement is in electrics , the entire wiring system on the bike feels cheap and un reliable frequent loose contact of the switches is very common among the riders and  quality of switch gear also seems to be low which don’t offer a good feedback when pressed . The ignition system (TCI) has also been complained about for its failures.

 Royal Enfield UCE Engine

The new unit construction engine houses the gearbox inside the engine casing unlike the older CI engine, that doesn’t make the gear box smooth and slick, occasional jamming and difficulty in upshift is observed while noise and vibration at high rpm is prominent. Due to the issues in the clutch gear shifts sometimes seem to be difficult.

The Engine depending on the air for its cooling needs suffers occasional over heating while moving through heavy traffic and continuous rides at low speed .this leads to the serious rise in temperature in the engine, the seals and gasket employed on the engine harden up and fail which leads to the leaking of the engine oil from the cylinder head through the rocker covers.

Other small issues are part of life of the bullet rider, The slacking of the chain, loss of the tension in the primary chain, rudder of the swing arm, noise from the valve mechanism, de carburizing of the engine, frequent wear in the almost all the bearing employed on the bike, make maintenance a daily affair in the life of the Royal Enfield owner. & helping solve this issues make a mechanic your one of the best friend.

Royal Enfield ENGINE Overheating

 Royal enfield 350 cc or 500 cc single cylinder engine is above the limit size for an air cooling unit. While other manufactures adopting liquid cooling system for the displacements more than 200 cc, helping them utilize higher compression ratio and thus extract more power from smaller unit.

The unit on the Enfield gets a distinct look from the cooling fins provided on the engine , which would rather spoiled if liquid system was being installed , and an entire redesign of the engine would lead loss of identity to the bike . Ride on open roads provides enough flow to keep the cool and maintains a good working temperature. Constant rides at low speed heats up the lot and Air cooling system fails to deliver optimum performance.

Many problems are followed by this overheating issue. The rocker cover gasket, which is continuously in contact with the cylinder head and hot engine oil pumped to the rockers hardens after certain period of time and losses it properties thus oils flows out of the cover. If let unnoticed the engine oil level may fall and may lead to serious problems in the engine.

 Royal Enfield ENGINE Knocking

Due to overheating if temperature of the unburnt mixture exceeds the self-ignition temperature of the fuel and remains at or above this temperature during this preflame   reaction (ignition lag) spontaneous ignition or auto ignition occurs this leads to knock . Knocking very dangerous phenomenon which might damage the piston and bore. Might also lead to damage to the valve, the large vibration due to knocking may cause high stress in the structural members on the bike. The pressure pulse due to the knock leads to vibrate the entire combustion chamber , affecting the geometry of the engine .

Combustion process is also affected due the rise in temperature. The charge is not properly burnt and carbon deposits form over the piston and valves

ROYAL ENFIELD MOTORCYCLE CARE

ROYAL ENFIELD MOTORCYCLE CARE TIPS

For a Royal Enfield motorcycle the most important thing is care.It is not like any other bike in the market ,it needs to be looked after ,loved and maintained well so here are some tips you should remember for keeping your bike in good condition.

Check list

1.     First the tire Pressure should be proper, Should be checked by pressing the handle bars and pillion seat

2.     Engine oil level, should be within the marked limits

3.     Chain slack should be around 25 to 35 mm (tight or loose chain is not good)

4.     Battery voltage, check whether it is charging while engine is running

5.     Check for any unfamiliar sound from the engine

6.     Check for clutch free play, gentle engagement of clutch without jerk should be set

7.     Fuel level

8.     Check for any signs of oil leaks from Engine

Bullet Engine

Royal Enfield Bullet Engine

UCE ENGINE

AVL ENGINE

UCE 

CI ENGINE

The 350 cc single cylinder air cooled unit found on the bullet is a legend which has been in the market for around 50 years. The engine had undergone a make over by an Austrian company AVL which made modifications to the engine to improve its performance.

The improvements made by the AVL company were not enough to give the BULLET a rebirth, the problem from the older CI engine persisted in the AVL as well. It was very essential for ROYAL ENFIELD to take step to prevent this drowning Brand. 2007 the Royal Enfield re launched the Iconic Bullet with the all new UCE engine

Unit Construction engine (UCE) was all new but had the DNA of the BULLET. The engine looked mature, premium and well-Engineered. Blend of technology and vintage looks was perfect. It made every Royal enfield enthusiast heart pump up.

In the UCE engine The engine, gearbox and clutch cases were three different units altogether connected to each other independently. So what happened was you needed to change oil at three places each time. Now, that is a messy thing to do, and also considering the various gaskets that required replacement frequently, in simple terms, it was maintenance heavy.

 The engine was separate from the gearbox and the clutch, a lot of power used to get lost in terms of transmission losses as the set up is not as efficient as modern engines. so, not only were the Cast Iron and AVL LB Bullets delivering lesser mileage but they were also making lesser power at the rear wheel even though they were making decent power at the crank shaft. The Cast Iron and AVL 350cc engines both produced 18 Bhp at the crank, but this figure went down to 12 Bhp at the rear wheel. Power loss: A whopping 33%. Culprit: Transmission losses.

UCE 350cc engine produces about 19.8 Bhp at the crank shaft. At the rear wheel, the power is about 16 Bhp. So, that is only 20% power lost in transmission losses, which while still a lot in terms of modern motorcycles, is fair enough for a Royal Enfield.The Unit Construction Engine is more fuel efficient than both the Cast Iron and AVL Lean Burn engine by almost 20%. While the 350cc CI and AVL engines used to deliver 30 kmpl, the UCE engine consistently returns 40 kmpl.

Royal Enfield comparison

Royal Enfield comparison

How are the Royal Enfield motorcycles different from rest of the other bikes lets find out

 Royal enfield Bullet 350 cc  four stoke engine churns just 20 bhp .That figures are something any other 200cc engine  would easily throw up ,why it takes so much the displacement for the Enfield to pump the same power.

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 The following article will discuss the performance of the Royal Enfield bullet 350 over the pulsar 200 ns

Engine     Royal Enfield Bullet 350

Type	Single Cylinder, 4 stroke, Twinspark
Displacement	346cc
Bore x stroke	70mm x 90mm
Compression Ratio	8.5 : 1
Maximum Power Maximum Torque                                       28 Nm @ 4000 rpm	19.8 bhp @ 5250 rpm

Engine      Pulsar 200 NS

Engine	4 Stroke, 4 Valve, Single Cylinder, Liquid Cooled
Displacement	199.5 cc
Bore and Stroke	72 X 49
Compression Ratio	11:1
Max. Power	23.52 PS @ 9500 rpm
Max. Torque	18.3 Nm @ 8000 rpm

From the above figures , the pulsar with just 200 cc engine produces the peak power of 23.52 bhp whereas the Bullet with the 350 cc just 19.8 bhp . Pulsar torques 18.3 Nm and the bullet 26 Nm.

These figures say a different story, the bullet pumps max power and torque figures at as low as 4000 rpm where pulsar needs to be revved really hard at 8500 rpm to gain all the potent torque and power from the engine. This makes the Bullet a cruising machine with all the torque and power highly concentrated at the mid-range , and lot of it available from just the start of the engine.

Following are power vs speed and torque vs speed graph of Pulsar 200 ns and Bullet 350

I have calculated this values from the pressure reading obtained from the engine cylinder of both the bikes ,errors may be present in the readings

Royal Enfield vs Pulsar 200 ns performance

This makes the  Royal Enfield bullet compared to pulsar pull effortlessly from stand still and with heavy loads and climbing uphill . Torque and power characteristics have wider bandwidth then many other bikes, which reduces fluctuation of power in the rev range.

The ratio of bore and stroke of engines are the reason for the performance difference. The bullet has larger stroke and smaller bore 70 X 90 mm. where the pulsar 72 X 49 mm the ratio is 1.46 for pulsar and 0.77 for the bullet.

The short stroke pulsar produces great acceleration but lacks power and torque at lower rpm. The short stroke makes the engine to move reciprocate faster hence this choice of ratio is prominent in the sports bikes.

 Royal Enfield Bullet has larger stroke and smaller bore, the large crankshaft induces a larger turning moment and generate huge torque. The large stroke also leads to the starting trouble of the bike and a heavy flywheel is also needed for dynamic balancing on the engine  . This character of the engine makes it slow in acceleration compared to the competitors.

The compression ratio on the pulsar is 11:1 while on Bullet is 8.5 : 1 , so there is  less pressure inside the bullets cylinder makes it develop very less power for its offered displacement . Bullet also employs air cooling system while most of the bikes of its class have a liquid cooling to dissipate the heat from the engine. hence use of the higher compression ratio in the bullets cylinder is avoided , which may lead to the overheating .

The pulsar breathes through a 4 valve system, 2 for intake and 2 for exhaust and 3 spark plugs to burn the charge. Enfield has 2 valves and twin spark plugs.

4 valve system is quite effective which offers efficient scavenging of exhaust gas from the cylinder at the end of the exhaust stroke, thus preventing the dilution of the fresh charge . the 2 valve in the bullet does the job very well but at higher speed the performance is compromised . leading to occasional miss firing of the engine 

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The following characters make the bullet a cruising machine , for moving at speeds of 70-80 for a long time effortlessly

and pulsar racing machine  which loves to be accelerated hard, turned into corners , cutting through traffic and drag racing.

which makes both the machines entirely different from each other and suitable for different purposes.

About

About me

Hi, I am Mayank Ganatra a Mechanical Engineer from Mumbai (India).  Being a Royal Enfield fan ,I have researched a lot about Royal Enfield motorcycles , mostly regarding there repair and maintenance. I have found many solutions to the problems which are commonly occurring in the motorbikes and also developed simple ways to rectify those.

For any of your  issues with your bike  your can contact me and will provide the best solution as soon as possible . post your problems in comments or mail me :- metaltrixxmotorworks@gmail.com

I will be writing detailed article on every problems and also providing tips for your bike stay tuned to the blog , Thanks for reading