Running 640 on poor fuel
I'm doing a trip up west africa in December and have been told to expect very bad quality fuel.
What can i do to best prepare my 640 adventure for poor fuel? One guy told me we're likely to burn holes in the pistons????
Don't worry about it
I wouldn't be too concerned. I did West & East Africa on 640 Adv and LC4 400 2002/3 and had no bad fuel issues. Try to fill up at the main brand stations (Shell, BP etc). I'd heard that smaller "uncle Joe's" corner stations often dilute their fuel to be able to sell more so I avaoided these.
I did fit a big(ish) inline fuel filter in between the fuel tap and fuel pump. As a precaution I took a small bottle of Octane booster to use if I heard the engine starting to ping because of low octane fuels ... I only used this once after filling up at a dodgy little station in Nigeria. If I knew that I would be pushing the fuel range I carried an extra 5 ltrs strapped to my pannier rack & topped up into my tank asap.
It's unlikely you'll find any unleaded fuel south of Morocco (at least that was the case 3 yrs ago) which over a long time can clog your catalytic converter. Still got my 640 and it still runs fine after running on leaded fuel for 9 mths.
When you notice the pinging or think you have a batch of doggy petrol do the following.Open the cover on the right hand side of the bike (one opposite airfilter cover), you will notice a little plastic box with a load of electrical wires going into it (dont fiddle with it as this is your cdi unit).
When looking straight at it on the left hand side of the little plastic box(cdi) there should be male/female connection switch (The so called switchable cdi, well thats the switch). By undoing this connection you will change the compression setting of the bike. There will be loss of power and the bike will also sound a bit like a diesel motor, but the engine will be fine and capable of getting you where you need to be.
Also dont gun the engine when the pinging starts, thinking it will go away.
If the above is a bit to much, email me and i will send you the KTM notice with pictures for changing it.
I also second the inline fuel filter and also put lady stokings over your tank inlet to act as an extra filter when you stop at "Johnny No Names Petrol Station"
You will need a new CDI to upgrade your model to use the 2 curves.
If you do not do this, then you then have only 2 ways of improving the ignition process:
1. Add an octane booster
2. Slightly loosen your generator srews and move it to the left (as the screws allow) This will give you a little earlier ignition and eliminate most of the "klonck".
Although I did both, the 70 octane gas in Bolivia killed my piston while I had over 2500 km with that bad gas then later in Chile. Thats life.
So plan your trip carefully and look for branded fuel.
Thanks guys for the brilliant advice.
Ran 80 in Mongolia and although I have the dual curve ignition I never changed it.
The bike ran fine and I never heard detonation.
In fact I often run regular gas or mid range. I goes fine.
I had the head off due to a head gasket failure and saw no signs of lean running or detonation despite the gas and stock jetting with the competition pipe. I removed the snorkel and enlarged the hole.
My bike runs great with the stock BST carb.
I would think that changing the timing so the engine fires earlier would add to the detonation problem.... Retarding the ignition should reduce stress and cylinder pressure.....
I added a 2003 CDI to my 2002 640 and placed a switch on the dash so I could switch between high and low octane fuel.
I ran it on 80 octane with no problems, but big throttle openings on 76 octane fuel would make it ping.
with the CDI on the high octane setting the lowest fuel I could run without inducing pinging was 92 octane.
Petrol/gas does vary from place to place. My Honda transalp seems to run on anything down to 85 octane without any problems, apart from loss of power.
The KTM part number for the CDI box was.. 58439031300 I think it cost around 200 euros.
Me and 2 other friends is currently in burkina faso,we are doing west africa the opposite way
stqrted in london and coming down to SA
ons kom almal huistoe na n paar jaar in london
We are all riding with 640 adventure and have not had any problems with bad fuel sofar.
we can keep in contact and we should pass each other along the way,we are planning to be in sa end of january,gabon during christmas.
anything else,just give a shout
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