Step by step: From general maintenance to complete restorations, we share tips and tricks for working on classic bikes.
Royal Enfield pitches its retro-inspired motorcycles as simple, down-to-earth machines. Powered by an overhead valve, single-cylinder engine and designed to appeal to novice and experienced riders alike, they promise ease of riding and maintenance thanks to their straight-forward architecture. After putting 1,000 miles on our long-term 2015 Royal Enfield Continental GT, we found the GT to be a fun urban machine, accessible and friendly. Conducting a basic maintenance regimen of oil, spark plug and filter change, we discovered it’s quite easy to work on, too.
The first thing we did was change the oil, which we’ll detail below through photos and captions. A few notes, first, however. The GT is about as bare-bones as they come. That’s a good thing when it comes to maintenance, because you don’t have to remove acres of plastic to get to service parts. In fact, the only piece of bodywork that comes off for this work is the right side cover, to access the air filter, and that only takes one screw. That’s it. Even the gas tank can stay on when changing the spark plug.
That’s the good news. The not quite as good news is that changing the oil is a messy affair. The new unit engines, first introduced to the U.S. market in 2008, have proven to be reliable, long-lived units and an excellent improvement over the earlier engines. Yet they still have their idiosyncrasies, evidenced by the six – count ‘em, six – separate O-rings and crush washers required when changing the oil. And that’s not counting the one tiny O-ring supplied in our oil change kit we never identified, nor is it identified in the Continental GT Owners Manual.
There are two oil drain plugs and a separate drain plate. The oil filter is mounted horizontally in the engine’s right side cover; it can’t be removed without dumping oil on the side of the engine and on the exhaust pipe. Granted, it all cleans up easily enough, but it strikes us as an oversight that Royal Enfield didn’t give this aspect of the engine more thought, especially considering that the unit engine was a clean sheet design.
The other thing that struck us is the poor location of the crankcase breather tube, which is mounted directly forward of the screw-in oil filler cap. That wouldn’t be so bad if the tube didn’t immediately elbow 90 degrees rearward. Because of its location, it has to be pushed out of the way to remove and install the filler cap. Simply running the line straight up an inch or two before elbowing back would solve the issue. Over time, we wouldn’t be surprised to see the tube or its elbow fail from being moved around every time you add oil.
Ignore those idiosyncrasies, however, and you’ll find the Enfield unit engine is indeed easy to service, as we show you below. As a matter of protocol, make sure to warm the engine fully before changing the oil. That helps to ensure contaminants are fully suspended in the oil so they’ll flush out during draining.
Identify the two drain plugs and the one plate to be removed. The front drain plug is at upper left (it’s a little out of focus in this shot). The rear drain plug is at right center, and the drain plate is at center, held by two 8mm bolts.
Using a 19mm socket, remove the rear drain plug and let the oil drain out. Use caution as the oil will be hot. Note that the drain plug is magnetic to trap any metal particles in the oil.
As the accompanying photo shows, we found metal particles on the magnetic plug. That’s quite normal on a new engine just breaking in, as was the case with our Continental GT, which we received showing fewer than 100 miles on the odometer.
With a 12mm socket or box-end wrench, remove the front drain plug and let the oil drain. Don’t be tempted to leave the front plug in place, thinking that the rear plug, which is lower, will effectively drain all the engine oil. We were surprised how much more oil came out after removing the front plug.
Using an 8mm socket, remove the two bolts securing the drain plate. Very little oil came out when we removed this after removing the rear and front drain plugs. Like the rear drain plug, the plate has a magnetic core, which also had attracted some metal. Note the O-ring that seals the plate.
Using an 8mm socket, follow a cross pattern and slowly loosen the three bolts that hold the right side cover for the oil filter. We loosened the cover until oil started draining from the filter housing, then let it drain for a few minutes before proceeding.
The cover incorporates a spring that holds the filter in place under pressure. Continue unscrewing the three bolts, working evenly. The spring tension is almost gone once the bolts are fully loosened.
Remove the oil filter cover, noting the O-ring that goes between the spring-loaded plate and the oil filter. The O-ring stuck to the plate when we removed it.
Remove the oil filter. It’s set back inside the cavity; we used a pair of needle-nose pliers to retrieve it.
Remove the rear O-ring that seals the oil filter at the back of the oil filter cavity.
These two pictures show, respectively, the individual O-rings (the first photo shows only one of two oil filter O-rings, second from left, and the O-ring we couldn’t identify, fourth from left), crush washers and oil filter we got from Royal Enfield and the O-rings and crush washers installed in their respective parts. Note the lone O-ring next to the new oil filter; it goes into the oil filter cavity before the oil filter. Install the two drain plugs and the drain plate.
Apply a film of fresh engine oil to the oil filter O-ring.
Install the O-ring in the filter cavity, making sure it’s pushed all the way home.
Soak the oil filter in fresh engine oil. This ensures there’s oil in the filter on start up so the system primes quickly.
Install the new oil filter.
Apply a film of oil to the second oil filter O-ring and place it on the spring-loaded plate. You can simply push it into the cavity and onto the face of the filter, but we found it easier to locate this way as the plate also acts to center the oil filter. Push the plate in place, then reinstall the three bolts securing it to the engine. Working slowly in a cross pattern, tighten the bolts until the cover seats, then give the bolts a light nudge to ensure they’re tight.
With the drain plugs and drain plate in place, we cleaned off the bottom of our engine. Why? Because we like clean engines.
Fill the engine with fresh oil. Royal Enfield specifies semi-synthetic 15w/50 API SL Grade JASO MA oil. We used Spectro Golden 4 semi-synthetic, which meets all of RE’s specifications.
Make sure not to overfill the oil. It took a little under 2.5 quarts to fill the GT. We filled it until the oil level was at the top of the sight glass, then started the engine and let it run for a minute. After turning it off and letting it sit a minute, the oil level settled right about where we wanted it, which was just above halfway on the sight glass.
Done with the oil change, we removed the single spark plug. It can be removed with the tank in place if you use a 13/16-inch box-end wrench on a spark plug socket. Otherwise, you’ll want to remove the tank. Here’s our plug, perfectly serviceable and showing the engine is burning clean, as it should after only 1,000 miles of riding. We put it back in.
Remove the single Phillips head screw at the bottom of the right hand side cover and remove the cover to expose the air filter box.
Remove the four Phillips head screws securing the air filter cover to the air box and remove the filter. As you can see, our filter still looked brand new, so we put it back in service. Given its ample surface area, we’d anticipate it lasting 5,000 miles in urban riding. Royal Enfield suggests changing it every 6,000km, or approximately 3,700 miles. MC