Reducing the final drive ratio will bring your powerband into better alignment with the speeds you want to operate, but it will not improve your rate of acceleration. It's a good modification for Texas where the speed limits are high. You should consider it. I'm not a big fan of chains. IMO Dave's pulley mods are a much better solution. If you haven't seen the post here it is.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1384949185I doubt that there is any more parasitic power loss with a belt vs an o-ring chain, and you don't have to deal with that filthy mess and the constant adjustments. The belt is "set it & forget it".
If you want to give that 40 incher a bit more air this old post should be helpful. The airbox mods are free and they work good. I like the airbox because its quiet and provides excellent weather protection. There's a lot more flow to be had on the cheap.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1523302904The stock muffler can be easily modified and, contrary to popular opinion, it works well. It's also very quiet, even with the mods. It's a bit of work, but well worth the effort. I admit that I made my fittings on a lathe, but they are all simple, and a resourceful type could pretty much achieve the same results with some conduit and steel plate fabricated with a hacksaw, files, hand drill, and vice. It's the concept that matters. This old post gives all the specifics on the stock flow path and how to improve it. You could just punch a big hole through the internal plates but that's crude man, and the noise sucks. I've actually kicked mine up a notch further by drilling more and larger holes in plate "C", and increasing transit tube 3 from 1/2" to 3/4". It's still very quiet and plenty frisky.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1526453881The cam in question is for a 1995 or earlier DR650. It's cheap. Installation is easy. It works good. It seems to hold up well even without the oil holes in the lobes. This old post gives you the low down on the DR650 cam.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1525327311If you change your cam, this sealant applicator works wonders. Correct sealant application is very important on this engine. If you apply too much it fouls the oil flow path and can result in serious damage.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1525551307I am confident that if you do these three mods you will be much happier with your freeway trips.
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