Wednesday, April 14, 2010

Think before you 'repair' a Royal Enfield

Note the hoses on each side of the carburetor.

Anxious to start riding, I wheeled out my 1999 Royal Enfield Bullet and kicked twice. Nothing.

Never a cause for alarm! Three kicks usually will do it but, just to add a bit of insurance, I reached down to turn on the enricher. Nothing like lots of gas to cause an explosion.

Doing so I noticed that the delicate rubber tube between the air filter box and the carburetor was badly torn. A gaping hole had developed. No doubt it had been ripped by the sharp edges of the hose clamps holding it in place.

No cause for concern! I have a box of hoses I've ordered over the years and even a stout hunk of radiator hose cut to length. One of these bits would soon have me on my way.

Unfortunately, it proved impossible to get any of the new hoses onto the air box outlet. Too tight.

No problem! I wheeled the Bullet into the garage and a few moments with a wrench had the air box off. Now I could really lean on it with all my weight. But the hose still wouldn't go on, no matter how I stretched it and pushed.

Not beaten yet! I called to the wife to start boiling water to soften the hose. We'll have this baby on the road in no time! A bit of a soak in a pot of boiling brew and — no — it still wouldn't go on.

Never say die! I pulled out a round file and began scratching away at the inside of the length of radiator hose. I would open it up a little bit to make it fit, I thought.

Much huffing and puffing later it was apparent that the radiator hose would never go onto the air cleaner outlet no matter how much I filed. Radiator hose is tough stuff and it had a long way to go before it would fit.

Now, I slowed down and started to think, which is what I should have done in the first place.

I finally realized that the hose bits weren't wide enough to go on the air box because they were made to connect the carburetor to the motor. A wider hose (which I didn't have) connects the carburetor to the air box.

Two sizes of hose! Of course. Probably has something to do with narrowing the air passageway to speed up the flow of the gas/air mixture into the engine. What genius these engineers have. But, now what?

The answer gently dawned: the air hose from carburetor to motor is absolutely critical since any air leak here thins out the mixture carefully produced by the carburetor.

But the air on its way into the carburetor from the air cleaner is nothing special. It's just air, and if it gets mixed with a little more air, that is no problem.

I ruefully realized that I probably could use a toilet paper tube for this connection; in fact, I was tempted to do so, just to show the Bullet how much I appreciate being the fool.

No. That would be wrong. It wouldn't be waterproof and there might be enough suction from the Bullet's mighty 500cc motor to collapse the cardboard.

I got out some black plastic tape and repaired the original hose. As I did so, I noticed that it had tape on it from the previous time I'd done this.

And we were off!


  1. Nice, After trying many types of rigid and semi rigid hoses between the carb and pod filter that I have I ended up using an old vacuume cleaner tube for the air intake as its much more flexable. Doesn't look to bad either. Toilet roll tube is a good spare!

  2. yes when go for the repair your bullet you need to think all the thing before it and it will benefit you in repairing.

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