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Seven Months In

28/1/2019

Not a lot done on the bullet as I have spent most of the last six months restoring my BMW.

I have done a few electrical changes documented here. The only other changes are fitting a better refector headlamp clamp - after I arrived home with the headlamp resting on the front mudguard and hanging on by the wires.

I am still very happy with the bike, I wonder if I will still be as happy when I get the BMW on the road.  Actually I think I will. The roads around here are generally fine for the Bullet, but a little bit more power would be appreciated for overtaking lorries.

So I digress into a discussion on power and speed.

Power and speed

The Bullet has a top speed of around 70mph and bhp at the rear wheel is about 16bhp.
It weighs about 200kg and I weigh about 80kg so all up we are looking at 280kg or 617lb.

A handy calculator is here. Putting in the above figures and adjusting the friction coefficient to arrive at a top speed of 70mph (I arrived at 1.44) gives us a starting point.

Top speed is not important for me but being able to overtake lorries on the motorway is. Lorries in the UK are limited to 60mph so the time to get from 55 to 65mph is important.

In this case it is around 9 seconds

Upping the power by 4bhp takes the top speed to 7 5.5 seconds from 55-65mphThat would be enough for me.

As a sanity check, the BMW with about 44bhp at the wheel gives a top speed of 100mph which is about right. The 55-65mph time is 1.52 seconds.

Hitchcocks dyno graph

Hitchcocks dyno graph

This shows an increase of 4bhp just by changing the silencer. Currently I have the original Brituro silencer and a K&N air filter. Interestingly the also shows peak power is at 4500-4700 rpm although the hand book says 5400rpm. With the standard 17 tooth sprocket the 55-65mph corresponds to 3557 - 4204 revs. Average power in this band is about 3 bhp above standard. Probably good enough. That's a fairly cheap mod.

The bullet can be tuned further, but if I increase the power by mods to the cylinder head etc., then the con rod becomes the weakest link. If I change the conrod for a steel one it will cost a lot of money and a complete engine strip down and a specialist shop to do the change. 

But if I run it at around 50-55mph only speeding up occasionally and don't chug along at too low revs then the engines should last me out.

 

LONG TERM STRATEGY (and ramblings)

It's funny how opinions change.  When I bought the Bullet it was simply a stop gap until I got the BMW back on the road.  I have spent a lot of time on this and it's still not quite ready.  The engine runs but a carb needs sorting and I get a worrying clicking noise from the drive shaft when I rotate the back wheel by hand.  No big deal.

But Bullets grow on you.  It's a simple engine and in an eye catching bike.  I feel loth to part with it when the BM is up and running.  I also suspect I'll use the Bullet more. 

So towards the end of summer it is decision time. Options are:-

  1. Sell the Bullet, keep the BMW
  2. Sell the BMW keep the Bullet
  3. Keep both
  4. i. above followed by buy a Himalayan or an Interceptor
  5. ii. above followed by buy a Himalayan or an Interceptor
  6. Sell both and buy a Himalayan or an Interceptor
  7. Accept I am too old and sell them both

iii. and buying a Himalayan or an Interceptor is a non starter due to lack of space.

Currently I think ii. or vi. are the main options, but let's see what a summer of riding the BM and the bullet does.

Update, (July)  I went to see a Himalayan, and an Interceptor was there too.

 Really, the Himalayan is not my type of bike - I don't do off road riding very much.  It has not much more performance than the Bullet, with vastly more complications. I prefer the Bullet, especially for looks.

As regards the Interceptor, it looked like an early Japanese bike.  Obviously much more power than the Bullet, and probably similar to the BMW.

I don't think a new Enfield is on the cards, which drops the options to i, ii, iii, or vii.

Update, (August). I took my courage in both hands and tried the bike flat out to " see what she'll do".  On the flat, I managed 83mph on the clock in one direction  and 67mph in the opposite direction.  On the GPS this was 75mph and 60mph. The 15mph difference can be explained by the fact that there was slight headwind in one direction and tailwind in the other. It is not unreasonable to assume that the maximum speed in still air is about 67mph or 75mph on the clock.

In reality, I am not going to be doing a lot of riding.  I used to use bikes for commuting to work, and trips out around Scotland at the weekend with friends.  But since moving to Cornwall I have no motorcyclist friends.  So it will be the odd ride around Cornwall. I would guess 100 mile round trips are the most I would do.  Even with one a week that's only 5000 miles a year, but I think due to weather it will be more like one a fortnight. That's only 2500 a year.

Two bikes is a bit of a silly option.

I am now 70 - I may be riding for another 10 years.   That's 25,000 miles.  The Bullet has got 7000 miles on the clock - will it still be running with 32,000 on the clock.  Would a Himalayan?  And how much work would be needed to keep them on the road.

The BMW would easily do another 25,000 miles even with 45,000 already on the clock. I've changed the handlebars to get a more comfortable riding position (like the Bullet's). I need to ride it for a few hundred miles to get a feel for it.  Parts are much more expensive for the BMW but you don't need as many.

SO i. above is the sensible choice.  Let's see if the BM grows (back) on me after being off it for sixteen years.

 

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