Saturday 31 May 2014

Number crunching

We've been away on holiday for the week so no bike updates to report on.  Instead I've been crunching numbers.

mpg:
The second fill up showed that the bike returned 125mpg.  So, the 131mpg on the first fill up wasn't that far off.  However, the tank is going on to the reserve tap at about 3.5l, which is only ~90miles.  That's not far to go between fill ups when every minute counts.  I might have to look at modifying the tap to give more miles on main and leave myself with smaller reserve.  Or I could get really good at the mental arithmetic required to keep track of the miles completed on each tank...

Compression:
After the assembly of the top end I measured the compression, which came out at 120psi.  Now the rings and bore have bedded in it has increased to 140psi.  This is a good sign!

Average mph:
Thanks to an online matrix for the 2013 National Road Rally, courtesy of the Leicester Phoenix MCC, I've had a bit of practice at planning a route.  A Gold Award route needs to be between 500 and 540 miles according to the matrix (the actual distance may be a bit greater or less).  I pieced together a route of 505 miles, taking in 20 controls.

The rally is 20hrs long, less 2hrs of rest breaks (with particular restrictions on when those can be taken.).  Assuming that I take 5 minutes at each control and have 5 fill ups taking 5 minutes each, then I need to average 32mph.  If I allow for the matrix being 10% under on distance then this increases to 35mph.

Given that I'm struggling to hit 40mph on the flat then achieving an average of 35mph over this distance seems improbable.  Although the time I'm allowing at each control may be pessimistic.  I've not done the rally before so don't have a feel for how busy they get.

When Dad entered the rally he had to cover 600 miles, but had a genuine 24hrs of riding to achieve it.  He did stop for food and drink, but even taking 2hrs out for this the average speed he needed to achieve was just shy of 28mph.

What I need to do is a couple of long rides, to see what an achievable average speed is.  A job for one evening this week perhaps.  In advance of this I've had a look at some of the period articles on the bikes.  In John Thorpes book "The Book of the Honda", printed in 1964, he records an achieved average mph of 35mph for a C110 during Honda's successful attempt at winning the Maudes Trophy.  This arduous event involved seven days non-stop riding around the Goodwood race circuit.  That 35mph average should be optimistic for the road, as there were clearly no villages to slow down for riding around Goodwood!  It also managed between 124mpg and 140mpg.  So perhaps my mpg figures are about right.

He does say elsewhere in the book that the C110 can average 40mph on the road, but I can't see how that is achievable given the above.

Although I had initially set out to achieve a Gold Award, and would still like to, I will have a Plan B and a Plan C.  These will be to go for Silver (400 miles minimum) or Bronze (300 miles minimum) award instead.  I intend to plan out  my route with break points.  If I haven't hit particular controls by a certain time I will divert onto one of the shorter routes.

I've revised my goal to finishing the rally with an award, of whatever colour is possible!

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