Africa Twin riders often report problems while starting their bike after a longer time of standing around (three days and more). Several attempts have to be taken to start the engine.
Beginning with the 97 model Honda seems to have found a solution for that and it is easy to implement even on older Africa Twins (tested on RD03, RD04, RD07).
The changes from Honda at the RD07A
The source of the starting problem is, that the fuel in the carburator gets lost after some days of not running the engine.
Here are the Parts and the prices in DM you need (as in 1997):
Of course you can also use three standard t-connectors and about 1m of fuel pipe (6mm), available at every accessory shop. The costs are about 10,-- EUR.
The old and new ventilation system in comparison:
The floating chambers of the 2 carburetors are connected together on their upper side and out from these connection looks a short pipe in upper direction. This pipe is about 3cm long and it`s opened to its upper side, for getting air to the floating chamber's direction.
As far so well.
If the bike has not been started a couple of days (3-4 days) the fuel will evaporate over this pipe - Thats normal because fuel is a volatilely liquid. Now, if u`r trying to start your AfricaTwin after a few days out of order, she will not start immediately because of the fuel pump has to pump new fuel into the floating chambers until the bike comes back to life again.
The engineers at Honda built the following modification from RD07 into the RD07a.
Connect a tube from the carburetors connections upper opening, mentioned before, to the other ventilation tube (ending at the back side of this aluminium protection sheet metal below of the engine (you know what I mean?)
This ventilation tube has to be cut through at the most suitable place for being connected through a T-connector with the upper coming, new tube.
Actually now everything is finished, because the gasoline cannot evaporate any longer, because it cannot escape upward any longer.
But if Honda`s Engineers do something, then they do it right:
If u`re mud-jumping with your AT, it could eventually happen that this ventilation tube could get clogged. For still having the floating chambers being ventilated, here comes part 2 of this trick:
You have to cut the tube and set a second T- Connector in short distance of
your first done cut.
That was the whole Trick:
Now the fuel cannot evaporate anymore and your Twin will start immediately, even after 14 days standby. She will do it immediately after short pushing the button.
The needed parts had been mentioned in top of the page, and in addition every single honda dealer has got a pic from this whole action on micro-fiche, but u have to pay for this moidification for youself.
This modification takes about 30 minutes working time and u should remove the main tank for seeing what u`re working at.
Addon by Arjen Hoen:
I owe you a big THANKS for the simple and effective measure. The information on www.atic.org is also most helpful. However I do want to add some info: Firstly I noted different diameters of the original carburator tubes which have to be connected (>6 mm for the ventilation and 4 mm for the overflow tube). I went to my local autoshop to get the necessary pieces and this is what I finally used:
Costs: approx. 5 euro's! ;-]
I made the connection between the original ventilation and the new tube simply by forcing it 5 cm. inside. The outer diameter of the new tube corresponded with the inner diameter of the existing ventilation! 'Natural' resistance did the trick in my case...