Not so much a project report as a final write up, but here goes.
The Llanthoney trip finally convinced me the Bonnevilles range was too useless to live with. Coming home I set off with half a tank, so had to stop and empty the Jerry can into the bike while still in Wales. I made it as far as the M-42, but calculated I couldn't reach Donnington so stopped again. Having stopped short I then needed a third stop to reach Leeds without running on vapour. So, three stops in 220 miles, or half an hour wasted and a lot of pointless stressing and mental arithmatic
Solutions available were:
1. Norman Hyde 4 gallon tank at £800
2. Jerry can and pump set up like Julians.
3. Gravity fed auxilliary tank.
4. Cut and welded main tank.
The £800 thing is an insane amount to give a 50 mile increase in range.
I didn't like the idea of cutting my one and only tank, having a section welded in and resealed with Petseal.
The Jerry can and pump idea is the most promissing for most bikes and the cheapest. Fuel pumps can be aquired for under £75 and the can, wiring and welding would bring the whole project in at under £130. However, knowing the Bonneville carbs of old I know that any restriction in the fuel line has the ability to stop the engine. An experiment with a spigot brazed into a 10 litre can and pressurised with a fish tank syphon (the fish lived BTW
) proved this. The only solution then would be to weld a second feed into the main tank to even the pumps flow, giving the same issue as the cut and shut tank. Second hand tanks on E-bay go for over £100
Gravity feeding is much gentler, the carbs can take what they like via a simple T. Playing with the 10 litre can I found I could gravity feed to my hearts content. The problem with this is the shape of the tank. A jerry can needs a breather which with a vertical tank puts the weight too high and with a flat one would take up a lot of space and have a huge dead volume (or would spill on each corner). What I needed was a custom made tank. The first quote was £400
. Alifab however came back with a sensible £70
.
I had a standard seat base (use a K and Q seat otherwise the intercom makes a noise that goes "bum hurts, bum hurts, bum hurts...." whenever Karen rides on the bike) going spare. Removing the foam I decided to fit the tank to the base with it's own tap and an Enfield solo seat for me. The question is how big a tank?
Aircraft people and race teams know there is only one right amount of fuel. Too much and you carry weight when you don't need it (think of all those BMW's with £500 41 litre Acerbis tanks that only ever go 100 miles a day
). Too little and you stop too often and waste time. I therefore decided to base the auxilliary around a pair of ten litre jerry cans which gives me three set ups:
1. K&Q seat, standard tank only: 140 miles range, fine for family outings.
2. Solo seat & Aux tank: 240 miles range, for long distance motorway trips etc
3. As above but add 2 10-litre cans: 420 miles range for the desert/Norway with a single stop to empty each can into a tank.
The Auxilliary tank therefore needed to be 10 litres plus it's dead volume. Alifab did the job in just under a week. The results can be see here.
http://www.flickr.com/photos/31662519@N03/Andy
