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Modern technology really is better

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I recently bought a 1941 Indian Scout. I already have a Buell XB9S Lightning. Both bikes have ‘old technology’ pushrod air-cooled v-twin engines but where the Scout relies on a carburettor and a contact breaker type ignition circuit the Lightning has an ECU managed fuel injection system.

The Scout’s engine is essentially a 1932 design that Indian continued using until it went out of business in 1953. The Lightning’s engine was designed by Harley-Davidson in 1957 but the Buell version uses modern materials in its construction and Buell’s own engine management system. One of the more obvious differences between the 1941 Scout and the 2003 Lightning is that the Scout makes a little over 20HP from its 750cc engine while the Lightning makes over 90HP from its 984cc capacity. The specific outputs (i.e. normalised to 1000cc) are 30HP and 94HP. So the Lightning’s engine is making over three times the power of the Indian despite using a very similar design of engine. Modern versus old…

Other than power how much difference does all the modern technology make ? Well, here’s a side by side comparison based on a journey I needed to make into town earlier today…

One thing to note is that while most modern motorbikes have a single twistgrip for the throttle that is spring loaded to return to the closed position, the Scout has two non-spring loaded twistgrips. One controls the throttle and the other controls the ignition advance/retard. Because these twistgrips are not spring loaded they stay in whatever position they have been set to.

To start the Scout:

  • Open the fuel tap from the main petrol tank
  • Set the ignition switch to off
  • Set the ignition advance/retard twistgrip to one third retarded
  • Set the throttle twistgrip to one quarter open
  • Set the carburettor choke to fully on
  • Use three kicks to prime the engine
  • Set the choke to the start position (one click up from full choke)
  • Turn the ignition switch on
  • Give the kick start a single kick
  • It’ll usually start first time and then you need to adjust the throttle so that it’s just slightly open for a fast tickover and quickly move the choke up one more click to the ‘run (cold)’ position.
  • Leave the bike running for at least five minutes. As soon as you see dark smoke from the exhaust you need to move the choke up one final click to the normal run position and ease the throttle to the fully closed position.

That’s all there is to it. 😉

While the bike is ticking over the oil return needs to be checked by removing the oil tank filler cap. If the oil is returning from the scavenge pump in the sump then it’ll be pulsing out of the return pipe. If it isn’t, the ignition needs to be turned off immediately to stop the engine. The pump needs to be primed by forcing oil down the return pipe. The engine can then be restarted and the oil return checked again.

Halfway into town the Scout started hesitating and then cut out. I pulled over and tried to restart it. With a hot engine this needs a slightly different procedure:

  • Fuel tap on
  • Ignition switch on
  • Choke in the normal run position
  • Ignition advance/retard to between one third and one half retarded
  • Throttle to half open
  • Give the kick start a single kick
  • As soon as the engine catches quickly twist the throttle closed otherwise the engine will scream up to maximum revs in less than a second.

If you try to kick the engine over with the ignition advanced it’ll kick back and probably backfire through the carburettor too just for good measure. I never made it in to town as there was some dirt in the carburettor that caused the engine to repeatedly cut out and I counted myself lucky to get back home with it only cutting out once more while I was riding it. I can’t blame ‘old technology’ for this particular problem but there’s no getting away from the fact that the Indian’s 1930s technology is dirty, smelly, inefficient, and not completely reliable. The flip side is that it’s simple enough that it can often be easily fixed with little more than a few spanners and a little bit of know how.

I still needed to get into town so I wheeled the Scout back into the garage, remembering to slide a large piece of cardboard under the engine to catch the oil that it always leaks after it’s been running, and got the Lightning out.

To start the Lighting:

  • Turn the ignition on
  • Make sure the Kill switch in the run position
  • Push the starter switch

The bike always starts at the first push of the starter switch. The ECU lets the engine spin for at least three full revolutions before generating a spark. This ensures that the engine has enough speed and momentum to start easily and for the starter gear to disengage cleanly from the flywheel. The engine needs to be left for a few minutes to warm up. That’s it… Compare this with the procedure listed above on starting the Scout!

I rode the Lightning into town, parked up, visited the shop I needed to, went back to the bike, started it, and rode home again. No dramas. No smoke, no oil, no petrol. No smell.

I’ve never previously started and ridden the two bikes back to back like this and afterwards I couldn’t help making the comparison.


Written by Sea Monkey

January 7, 2010 at 8:00 am

Posted in Comment

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