I'm coming up on 14 yrs with the 640 Adventure and the only reason I am still running it is nothing else has come out that can replace it... A bit of a learning curve to get the bike sorted, but once done it is very reliable...

I have never heard of a LH crank seal issue or had a problem with the engine running hot, I think my fan has kicked on maybe 20 times in nearly 220,000 KMs, but I did install a SXC muffler... If you run the chain too tight, you will find that the O-rings behind the countershaft bushing will tear and cause an oil weep.. These O-rings are cheap and easy to replace, but it is easier just to run the chain with more slack...

The stock silencer is very restrictive to the point where it traps engine heat in the combustion chamber and that heat will shorten the life of the valve components... I found that the valve life pretty much doubled when running a more open muffler.. I got about 80,000 KM out of my last rebuild and to refresh the engine a new set of piston rings and a valve job were required, though I could of likely pulled 100,000 km as it still was not using oil.... Vibrations are there, but have never bothered me, some examples vibrate more than others, especially when they are not properly tuned.. They are tough bikes that survive being dropped quite well and they can also carry a load over rough ground as good or better than any other bike out there...

Changing oil is more of a pain on these bikes as they have both an engine and frame reservoir { the frame reservoir acts as an oil cooler} which both have to be drained... They also have 2 filters, of which I alternate, changing only 1 at an oil change.. Conventional tappets make valve adjustments easy, but you need to remove the tank, seat and fairing to get to them {8 bolts + covers}.. I change oil every 5000-6000 KM but if doing long distance where it tends to be easier on the engine will run up to 10,000 KM before changing.. Water pump gets new seals at 40,000 - 50,000 KM.. I used to change the intake cam roller at the same time as the water pump rebuild, but found I was changing out a good part... I now wait till that roller shows wear or gets noisy before I change it, my current intake follower has 120,000 KM on it with no issues.. Being out of production for 11 years you wonder about when the factory will stop producing parts, so far it has not been an issue...

I have looked at and ridden the Suzuki DR models and prefer the 400 to the 650... The 400 is a much better suspended, lighter bike with almost the same power as the 650.. Both have plenty of aftermarket support.. Travelers who ride the 650 prolonged off the beaten track with a load have had issues with frame cracking and gearbox failings after less than 50 k KM... Suzuki says they are not designed for this kind of use...

I was hoping that the 390 Adventure would be a worthwhile option, but after yrs of waiting nothing yet has materialized, maybe we will see a production model pop up at the upcoming bike shows..