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Royal Enfield Bullet 612cc - Part One
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Andy C wanted a big Brit single and so he bought a Bullet. But 500cc wasn't enough...

Back in 2003, I wanted a British 500 single, ideally a Gold Star, or a Norton, or even a unit 500 BSA. The problem with buying a genuine Brit single is that if, like me, you do not know much about them then there is a good chance you could end up buying a right dog.

Enter Watsonian Squire with the Indian-built Bullet. Even though it is made in India, it is still for all intents and purposes a British 500 single. I bought one in Sept 2003. This was before the advent of the lean-burn engine, which of course is not as authentic*.

Paint? We don't need no steenking paint... Royal Enfield Bullet Clubman GT Bullet

2004 saw me put about 2000 miles on it, and I started modifying it to get a little more grunt. Amal MK2 30mm Concentric, Boyer Ignition, Samrat rockers, 18-tooth gearbox sprocket, close ratio gear set. Don't mention money. If you embark on this kind of project, money always seems to become a secondary issue. It's what you are trying to achieve that matters. (At least that's what I tell myself).

All these goodies gave me a bike that had a fair bit more performance than standard - it would cruise at 65, but headwinds would kill it, it was still lacking that certain something: POWER.

2005 came and went and another 2000 odd miles were added.

2006 came around along with a surprise letter from my building society with news of an account I had opened years ago that I had since forgotten about. I looked at the balance and… let's just say that SWMBO agreed that if I bought her a new car, I could upgrade the Bullet.

Andy C (possibly) enjoying his Royal Enfield. Note injured right foot due to excessive kickstarting.

So it came to pass that after putting around 5000 miles on the standard motor, in mid-June 2006 I started the strip down in preparation for the 612 conversion.

Before splashing out the £1600-odd for the conversion (note: the 612cc performance kit now costs over £1800), I did a bit of digging around on various forums, asking people's opinions of the 612 Bullet. Without exception everyone said how good these conversion were. 'Virtually indestructible', 'cruise all day at 80mph on the motorway', 'don't ask: just do it'. The praise seemed endless. So with the cash burning a hole in my pocket I bought the various bits and pieces needed from Hitchcocks. I will take this opportunity to say that they are a thoroughly professional and helpful bunch. I did have reason to contact them on numerous occasions throughout the project as you will see…

There are a number of suppliers of big bore kits for Enfields around, but I decided to settle on the Hitchcocks version simply because there seemed to be a lot of them around, many of which seemed to lead some fairly hard lives, and information was easy to come by. I wonder what the Tollgate Classics 750cc conversion is like - anyone running one?

After just ten minutes work with a spoon and an adjustable spanner, this was all that was left of Any's motor. Hitchcock's 612 Big Bore Kit

Back to stripping the Bullet. The engine / gearbox strip is basically very simple and the only special tool I needed was a clutch hub puller. Removing the engine and gearbox from the frame is another story. Basically when you remove them, the frame loop springs apart slightly - I guess that the engine is effectively a stressed member.

I was very surprised with the amount of wear that I found in the main bearings. On both roller bearings the tracks had pits in them, and the rollers were chipped despite regular oil changes, and careful running in. The general response from people in the know with these Indian Bullets was 'no surprise'. It's a good job that I was replacing the main bearings! I was told never to contemplate using the standard Indian bearings with a 612 conversion even if they look OK - it's a false economy,

After stripping out all the Indian stuff and cleaning the cases, it was time to start rebuilding with the new Hitchcocks' components.

First thing to do was use a dremmel to take out somewhere in the region of 0.050" of the casting around the inlet cam. This is because the 'performance' cams have more lift than the standard Indian items and may not fit straight in. Depending upon your engine casting you may have to take out some metal, or you may not. So after removing the material and washing out the swarf, it was time to fit the new main bearings.

The Bullet has a single roller bearing on the timing side, and a much larger one on the drive side, augmented by a substantial ball race. SWMBO very kindly gave me permission to use the family oven to heat the cases (well they had been de-greased). Having warmed the cases, the roller bearing outer races virtually fell into the castings, as did the ball bearing. I just gave them a light tap with an aluminum drift to make sure that they were seated squarely.

Now it was time to fit the crank, and the start of a very frustrating time.

The 612 crank is I believe made by Alpha bearings, and features a 'large diameter' silver plated roller big end, and steel conrod. The whole thing is superbly made, and makes me wish I had see-through crankcases, such is the quality of the engineering. It weighs in at approx 26lbs, about 2lb more than the standard Indian item.

(The finish on the Indian items are very poor. No wonder they have a reputation for sometimes snapping the conrod when used really hard. The conrod is not polished and is virtually just as it left the mould, so is effectively covered in stress raisers. The finish on the flywheels is also very poor. One of my flywheels featured a large 'dint' in it. Allan Hitchcock reckoned it was probably put there by the Indian crank-truing wallah when he clobbered it with a hammer to true up the flywheels).

So there I am trying to get 26lb of precision-engineered crank into the timing half of the crankcase. But would it go in? Would it hell. It would engage about two-thirds into the bearing and then refuse to go any further. The crank would lock up, and you could not turn it. It was the same with the other crankcase half.

To cut a long story short, I took the cases and crank up to Hitchcocks, where Allan H and his team found that in my cases there was a cast web fouling the crank. This web is a normal feature of these cases, but is usually much smaller. A little careful fettling removed the offending metal - not enough to affect the integrity of the cases, it was just enough to prevent the crank from going in. I did admit to Allan and Co that I felt a bit of a prat, not noticing it myself. Allan's response was that his components should fit straight in, and this was as much a surprise to him as it was to me.

After a couple of hours I had a crank that would spin in the cases, and cases that were ready to be bolted up. Allan H was very apologetic about the problem, even though it was not their fault. So off I set back to sunny Somerset with a complimentary full gasket that Allan H had given me gratis. I think that you will find that this experience with my crank led to an extra line in the Hitchcocks' catalogue regarding the fitting of these cranks - winners all round.

Random Big Bore stuff on eBay.co.uk

Take two. The cases are re-assembled with the new crank easily spinning between the new FAG roller and ball bearings, the gearbox is re assembled to the engine, and I attempt to fit the engine and gearbox back into the frame.

Cutting another very long story very short… it is much easier to fit the engine to the frame first, followed by the gearbox, and then tighten up all the bolts. Fitting it in the frame as one unit is very difficult, OK near impossible. And to make future engine removals much easier (keep reading), it is best to make the gearbox-to-engine studs in effect very long bolts, by pinning the nuts to the studs.

So I had the engine and gearbox fitted to the frame. The rest should have been easy. Well… ere… it would have been if Hitchcocks had not sent me the wrong crankshaft. Oh dear !

It wasn't until I attempted to fit the alternator that I found that the keyway was in the 'wrong' place on the crank. this was because Hitchcocks had sent me the crank for a different model. Very apologetic was Allan H. Had I been living closer to Hitchcocks' premises Allan said they would have collected the complete bike, corrected the problem and finished the rebuild. Since we are some 130 odd miles apart, we agreed that if I removed the engine (good job I converted the gearbox bolts to studs) and sent it to Hitchcocks, they would pick up the cost of carriage, correct the problem, and despatch it back to me.

True to their word within a week I had the motor back with the proper crank fitted. A genuine error, corrected as promised. And Allan even posted me all the bits I needed for the 32mm Amal free of charge as compensation. You can't get much fairer than that.

The rebuild was eventually completed by mid-January 07, when it was ready to be fired up for the first time. It was with some trepidation that I flooded the 32mm MK1 Amal, and applied power to the Boyer. This thing felt like it had massive compression, and a kick back could prove very painful...

To be continued...

Royal Enfield Bullet Electra Clubman

*An Alternative
It may not be considered to be as authentic as earlier Bullets, but the current model Electra-X 500 comes with electric start, a five-speed gearbox, uprated brakes and about 30bhp when fitted with the straightforward highway kit. In Clubman trim with the Highway kit fitted, a brand new one costs around £4895.

More photos and details of Hitchcock's conversions are at www.hitchcocksmotor cycles.co.uk



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