Author Topic: Locking out Fifth Gear?  (Read 821 times)

0 Members and 1 Guest are viewing this topic.

nonfiction

  • Bulleteer
  • ***
  • Posts: 158
  • Karma: 0
  • New Bullet Owner/Longtime Bike Guy
on: April 18, 2022, 06:30:56 pm
An old Bultaco has become my 'trials' Bullet's stablemate over here, and that's prompting me to change direction on the Enfield a bit. I want to put knobby tires on and race some AHRMA vintage MX, alongside my buddies on AJS singles and Triumph 500 twins.

That means a lot of little changes and a few big ones. The biggest is probably the fact that AHRMA won't countenance the Enfield 5-speed gearboxes. Rather than swap in a 4speed, however, I'm considering locking out 5th gear, which I believe will pass tech... but I don't know how to do it.

So I come to you: Is there anyone here who can say with reasonable confidence what the easiest (and least likely to cause problems) path would be to locking out my 5th gear?

I picture a big zip-tie or a few wraps of safety wire might do the job, if wrapped and secured around just the right parts of the gearbox. But that's a very abstract idea. Thoughts anyone?



Paul W

  • Grand Gearhead
  • *****
  • Posts: 1,028
  • Karma: 0
  • 350 Bullet Electra (Indian home market).
Reply #1 on: April 18, 2022, 08:35:24 pm
I haven’t done this because I have no need; I’ve never heard of anyone else doing it either.

But you could probably do it by modifying the cam plate. This is the plate that rotates as you move the gear lever and has two tracks which engage on pins on the change forks. Perhaps the easiest way would be to tack weld across these tracks at the appropriate place, which would prevent the plate rotating as far as fifth gear.
Paul W.


axman88

  • Grand Gearhead
  • *****
  • Posts: 1,872
  • Karma: 1
  • Vintage Motorcycle Fan
Reply #2 on: April 18, 2022, 09:48:05 pm
I imagine I'm not the only one who would be happy to offer my spare 4 speed box for swap, and pay the shipping both ways too.


nonfiction

  • Bulleteer
  • ***
  • Posts: 158
  • Karma: 0
  • New Bullet Owner/Longtime Bike Guy
Reply #3 on: April 18, 2022, 10:17:39 pm
I imagine I'm not the only one who would be happy to offer my spare 4 speed box for swap, and pay the shipping both ways too.

Thanks for the kind offer. I'm not interested in being quit of the 5sp box altogether; I quite like it in fact. I would consider buying a 4sp box, but cost might be an issue (I'm spraying money around buying tires and number plates and pistons and whatnot for this bike as it is), so hoping to keep it simple and cheap, at least for this first season. Keeping the 5sp gearbox would let me use my new billet performance clutch from the good folks at Hitchcocks as well.


nonfiction

  • Bulleteer
  • ***
  • Posts: 158
  • Karma: 0
  • New Bullet Owner/Longtime Bike Guy
Reply #4 on: April 18, 2022, 10:18:56 pm
@Paul W thank you for the considered response. I'll look inside the box and see what I see. This certainly seems reasonable and reversible enough at first blush. Cheers.


cyrusb

  • Kept man
  • Grand Gearhead
  • *****
  • Posts: 3,616
  • Karma: 2
  • There's a last time for everything
Reply #5 on: April 19, 2022, 01:06:42 pm
Was eliminating fifth gear the recommendation of AHMRA? I ask because last gear be it forth or fifth is rarely used in motocross . Its not a "gear" just a straight shot from the clutch to the front sprocket in either transmission.
 I think AHMRA requiring the  the four speed eliminates the advantage of the closer ratio five speed, not eliminating last gear.
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


nonfiction

  • Bulleteer
  • ***
  • Posts: 158
  • Karma: 0
  • New Bullet Owner/Longtime Bike Guy
Reply #6 on: April 19, 2022, 05:47:28 pm
AHRMA handbook states this (of roadracing machines): "Royal Enfield Bullet built in India, four-speed; five-speed models permitted
only if the transmission is mechanically limited to four speeds"

But this makes me think I should dig more to find out, as five speeds are not explicitly called out on the dirt side. Hmmm.


cyrusb

  • Kept man
  • Grand Gearhead
  • *****
  • Posts: 3,616
  • Karma: 2
  • There's a last time for everything
Reply #7 on: April 19, 2022, 05:59:38 pm
AHRMA handbook states this (of roadracing machines): "Royal Enfield Bullet built in India, four-speed; five-speed models permitted
only if the transmission is mechanically limited to four speeds"

But this makes me think I should dig more to find out, as five speeds are not explicitly called out on the dirt side. Hmmm.
For road racing machines I would gladly eliminate first gear. But that is a pretty cryptic rule. Do they even mention motocross?
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


nonfiction

  • Bulleteer
  • ***
  • Posts: 158
  • Karma: 0
  • New Bullet Owner/Longtime Bike Guy
Reply #8 on: April 19, 2022, 09:26:55 pm
@cyrusB, yeah, same, only I'd happily toss 5th. I've been poring over the AHRMA handbook and not finding illumination. Next step is to seek out an AHRMA somebody who can answer definitively. They don't mention the gearbox in the MX section at all, which I'm not certain doesn't mean I can just run the 5. Which would be a big box ticked on my race prep punch list.