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Monday, October 17, 2011

Royal Enfield 5-speed gearbox will fit 4-speed bikes

Right-shift five-speed will fit four-speed Bullets.
Yes, you can replace the four-speed transmission of your Royal Enfield motorcycle with the new Royal Enfield five-speed transmission.

(In most cases; there are exceptions.)

You just purchase a right-shift five-speed gearbox, available, from Hitchcocks Motorcycles in the U.K. and bolt it up.

For some reason, I never realized this was possible, even when one of these gearboxes appeared on this blog, for sale in Jeffersonville, Vt. Its owner had purchased it, hoping to fit it to his 1957 Super Meteor twin. Unfortunately, that turned out to be one of the Royal Enfields it won't fit.

My eyes were opened when "Zack" asked this question on the Ace Performance Bullets Yahoo message group:

"Hitchcocks five-speed transmission; does anyone know anything about these? How much modification if any needs to be done to make them fit correctly?"

The answer came back from Tom Lyons, one of the founders of Ace Performance Products, which supes up Royal Enfield Bullets. Their claim is "We know what we're doing and we make it work for you."

Tom's reply:

"I'm assuming you mean the regular five-speed gearbox from the later models. You must get the right-side shift model, if you have a four-speed gearbox originally. The engines which came with four-speed gearboxes do not have the tunnel through the oil tank for the left-shift shifter rod, and won't work unless you have the right-side shift five-speed. Then it all bolts right up. They are very good, and are just factory Royal Enfield five-speed boxes from later models, and Hitchcock's right-shift conversion kit. Big improvement over the four-speed gearbox. Expensive, but a really nice gearbox that makes the bike much better all-around."

Readers chimed in. From "Dave" came this folksy and reassuring missive:

"Howdy. I've got one in my '99 bullet 500ks. Pretty much bolts right in. I don't recall having any difficulty."

And, "from Rick F":

"No modification required at all for my 2000-2001 500es Bullet. The only hard part is writing the check! Well worth it though."

Hitchcocks says of its transmission: "This is the gearbox which is fitted as standard to the new five-speed Bullets. We have converted this gearbox to a right-foot gear change and have modified the internals to give the conventional one-up four-down gear change (we can also offer one-down four-up). We can now offer this gearbox kit to fit any of the earlier Bullets, whether English or Indian. We have tested this gearbox since 2003 and have put it through its paces on the road and track. With its completely new design, it has performed superbly. It has vastly improved rideability and performance over the old four-speed models. It comes complete with new style clutch centre, clutch cable, gear and kickstart lever etc."

A chart provided by Hitchcocks shows that the five-speed starts with a lower (in effect) first gear, fills in the big gap between third and fourth and then ends up with the same 1:1 drive of the four-speed.

4-speed
5-speed
First gear 2.78:1 3.06:1
Second gear 1.84:1 2.01:1
Third gear 1.36:1 1.52:1
Fourth gear (big gap) 1.21:1
Top gear 1:1 (4th) 1:1 (5th)



Prices run from the British pound equivalent of $833 to $943, exclusive of VAT and shipping.

Hitchcocks' fitting guide claims the transmission fits 350cc and 500cc Indian Bullets, including Electric Start and the Sixty 5 and Electra X. It even fits the original, made in Redditch, England Bullets.

3 comments:

  1. Do I have to remove the 4 bolts that attach the 5 speed gearbox to the engine so that the gear change rod can be withdrawn from the engine

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  2. For some more clarification, let me ask a question - Let's assume if a four-speed gearbox can maintain 60 kmph @ 2500 RPM, is the gear box upgrade to a five-speed going to increase the speed at the same RPM on the fifth gear. Or is the fifth gear only an addition between the first and fourth gear for a better torque management? Thanks.

    ReplyDelete
    Replies
    1. If nothing else changes, you'd be going exactly the same speed in top gear with either transmission, and turning the same rpm, too. But you will have erased the big JUMP between third and fourth that hampers the four-speed, replacing it with nicely spaced gears all along.

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