Ace performance boost for Royal Enfield twins

You're looking into left cylinder of a Royal Enfield twin maximized for performance.

Ace Performance Bullets sells the bits it takes to make the single-cylinder Royal Enfield Bullet go fast. Now Tom Lyons of Ace has built parts that could pull super performance from vintage Royal Enfield twins such as the Interceptor.

"I'm not sure if you are aware of it, but we have finished a very nice pair of modded cylinder heads for the vintage Royal Enfield twins," he wrote me.

"This particular pair was for an Indian Trailblazer, which is actually a RE Super Meteor sold in the U.S. under the 'Indian' label, but these mods will be suitable for any of the RE twins in the 700/750 range, including the Interceptor.

Custom roller rockers.

"This mod includes a very nice set of custom steel roller rockers which fit into the small rocker area in these heads, and a set of added custom adjustment ports in the heads for adjusting the lash at the top.

"As far as I am aware, this is the first time that a Royal Enfield twin has ever had high ratio roller rockers put into the heads, and I believe that these are the highest performance Enfield twin heads ever produced. They are absolute gems."

Lyons wrote me that an Interceptor in full-race tune with these heads would have a potential of 90 horsepower.

"Just like we did with the Enfield singles, this unlocks the key to power that Enfields have been lacking all these years," he wrote.

First Ace turned the dray horse Bullet into a Fireball.  It adapted those improvements to the Big Head, AVL and UCE motors. It offers to fit Fireball improvements to the Musket V-twin Bullet kit. It is developing a bolt-on head to power up the new Royal Enfield Continental GT.

Now Lyons offers a way to turn the 60-year-old Royal Enfield twin into a threat at Bonneville.

Yes, I do feel self-conscious about featuring Ace so often on this blog. But it seems to me Lyons is the fellow answering all the "what if" questions people ask about Royal Enfields.

Bolt on power for your Royal Enfield Continental GT

Want to make your Royal Enfield Continental GT faster?

Ace Performance Bullets will offer a replacement head for the Royal Enfield Continental GT that will give street riders real world performance improvement.

The new head will line up with existing intake and exhaust components so that owners can swap it in and go riding. Best of all, owners won't need to rebuild the bottom ends of their motors to withstand the increased performance; the new head will make power within the limits of the existing Unit Constructed Engine (UCE) motor.

Ace built its reputation on the Fireball heads it still offers for iron-barrel Bullets. Owners must break the cases of these to install stronger (and pricey) bottom end components, while the stock heads are sent to Ace to be modified and shipped back.

"It was taking three months for each job, and this was something that we wanted to improve," Tom Lyons of Ace wrote on their Ace Performance Bullets Yahoo group.

"With the new heads, it should be available at fairly short notice, depending on how much I can stock at any given time, or short production time, so little or no wait. I think that this ready availability is something that people will appreciate.

"Also, it gives us the freedom to make a new head with a completely clean sheet of paper, other than having to have the inlet and outlet connections at the factory locations. We have freedom to design new combustion chamber, new ports, new valve angles and sizes and locations, new rocker arrangements, etc.

"We plan to pack this thing full of advanced features, and it will all be in the CNC program to cut it out of a big hunk of billet aluminum."

What followed from him were the technical details of high-ratio roller rockers, beehive valve springs and 6,200 rpm. Simple? No-o-o-o. Along with designing and manufacturing the hardware, Ace will need to reprogram ECU software, overcome the rev limiter and adjust mixture and ignition.

At what cost — for a brand new head?

"This is not priced as yet, because it is still not yet released, but we are expecting pricing to be in the $2,000-plus price range. We don't know yet how much higher than $2,000, but we are going to try to keep it as close to that as we can," Lyons wrote.

Ace offers a wide variety of other options — including making use of your existing head — and Lyons answers individual questions on the group. Indeed, he is one of the most helpful Royal Enfield "answer men" on the Internet, regardless of the question.

(You'll find his personal email address listed on the group home page, but please ask your question on the forum so we can all learn from the answer.)

It's fascinating to watch as Ace introduces one product line after another for Royal Enfield applications from ancient iron heads to the newest Continental GT.

It seems clear now that Royal Enfield motorcycles can and will go faster, reliably, if not cheaply. Seemingly under the radar of the most enthusiasts and the motoring press, Ace is leading the way.

I have no connection to Tom Lyons or Ace. I'll personally be leaving my own 1999 Bullet stock-ish (but, if I had a rebuild coming up...).

As an enthusiast I do appreciate Tom's willingness to answer technical questions for anyone, customer or not.

Ace takes Royal Enfield performance to the limit

This is not your average Royal Enfield Bullet motor.
(See end of the article for full caption.)

For April Fools Day 2012 I joked that Royal Enfield experts Ace Engineering could soup up NASA rockets to get humans to Mars faster.

I was only joking.

But the fact is that Tom Lyons and Sumanth Janardhan, creators of the Ace Fireball 535 kits for Royal Enfield Bullets, continue to tackle every challenge imaginable.

"I want to emphasize that we are not limited to what we put out in kit form," Lyons told readers recently on his Ace Engineering Yahoo board.

"The kits are simply a way for people to get a system that is tested and set-up in a package that will be easy to install for the average user.

"However, much of our work is custom work that is outside of the parameters of the kits we produce. We can meet these needs," he wrote, and he went on to give examples:

• "We have produced head mods with roller rockers and chamber modifications and porting for a highly competitive racing Bullet.


• "We are also involved in a land speed record project for a 700cc twin Super Meteor/Trailblazer.


• "We have recently accepted a job with the AVL head modifications, and are putting big valves and porting in that, and we also have the capacity to put roller rockers with high ratio into the AVL heads on request.


• "We can put the regular valve size or big valves into the UCE heads, and do chamber mods on it too, as well as the porting for various applications.


• "Roller rocker systems for the UCE are upcoming.


• "We have the GP head conversion with billet rocker boxes and alloy roller rockers with high ratio for the Iron Barrel models, which include specialized high port design with flow far exceeding anything else from anywhere else in the world.... We can do it on the Big Head too."

Enough, already? No.

He goes on to advise that Ace plans to offer options for Aniket Vardhan's V-twin Royal Enfield Musket including "fire breathing" modifications and even custom frames if needed.

More recent postings from Lyons have considered the possibility of developing four-valve heads for the Bullet and even water cooling.

Will all this really happen? Lyons' attitude is that it just depends on demand. Are there really enough people out there who want to spend the money it will take to go really fast on a machine that leaves the factory as a beloved but notorious slow poke?

"Our custom modifications are limited only by your imagination and budget. All you need to do is inquire," Lyons wrote.

As for the Ace Fireball 535:

"It's available right now, it has years of solid performance record behind it, and has over 30 running examples on the roads of five continents of the world right now; it's almost universally loved, has shown longevity for over 40k miles in some bikes so far, gets great fuel economy, and does the Ton and cruises at 75-80 mph. Everything has been worked out to 'the T.' Top to bottom."

The prices I've seen quoted for Fireball items seem reasonable. They don't include your labor to take apart the motor and install them. They also don't include the cost of perfecting the bottom end of your motor, without which  it will not endure the power the Fireball parts generate at the top end.

What is included is the personal touch. Here is Lyons' response to my request for a price list:

"The best way top handle the scope of available work and pricing is to ask readers to inquire about a quote for your needs. We have so many things which we can do that are not part of the kits, even as minimal as a valve job on their head that would improve performance. We could give the best answer if the customer inquires and we can tailor something exactly to his need."

What's that picture of at top? Lyons explains:

"Super Fireball Big Head showing the high-ratio roller rocker package on our custom valve spring stack with beehive springs, titanium retainers, custom big valves, in a Big Head which has our raised port with flow-matched manifold and all the Fireball features, in situ on a Bullet in the UK. This... has all our proprietary features which  are not available anywhere else in the world. This has the highest valve lift, highest port flow of any Bullet ever on record, and as far as we know, it is the most advanced and highest performance Bullet head in the world today, and in history. Made to be competitive with Manx and G50 racing singles on the track or street."

ACE high performance kit for Royal Enfield

The ACE Fireball 535 Royal Enfield High Performance Kit makes your iron-barrel Bullet faster. It's proven. It preserves practical power for street use. And it does not cost as much as you'd guess.

In fact, if you've been naughty and blown your Bullet motor you might even consider it instead of a standard repair.

I've monitored the ACE Performance Bullets project on their really outstanding Yahoo discussion group. If you have a taste for technical details and want to know how to make Royal Enfield Bullets go faster, this is the place to go for answers from Tom Lyons and Sumanth Janardhan.

They're familiar to those who follow Royal Enfield discussion groups as "ace.cafe" and "chumma". Nice guys, and they know a lot: they've been working on this for five years.

I've put off mentioning ACE Performance Bullets on my blog because I was afraid of misunderstanding technical matters. There's now an outstanding summary of the ACE Fireball 535 kit by Paul Crowe on the Kneeslider blog. It includes photos and videos and, perhaps most importantly, a price list.