Hi All, just reading some post & though I'd put my 2 bobs worths in.
Everything you have done is all good. As I have done some dynos from stock Muffler - Modify Original Muffler (Still quiet runs much better) - Ground out inner weld on header (Improves a bit more over stock) - sports muffler (Baffle in & out) there are considerable increases that can be made over stock without breaking the bank, while still having reliablity.
As you mentioned that you are happy with how the bike runs (not after WR 450 performance, if so get a different bike, expect to pay for it) then I suggest you do the inner weld mod as well.
I'm looking at opening up my exhaust port only (Do it on the bike) as I can block it off safely. I'm only going to open it up at the very front to alloy it to breeze that little bit better & see what we end up with.
Reason, being that to me the DR is a bike that is designed to run all day in stock trim (Realibility) but also has the protential to run much better with minor mods. (Very restricted bike in stock form)
Thanks for your time, Interested in any feed back or PM me.
Originally Posted by Dakar Dan
I'd recommend staying with the stock set-up with only light mods (snorkel out, drilled slide and raised clip, adjustable air-fuel screw and hex-key carb bolts) in conjunction with the stock pipe as a reliable, economical ride. I also replaced my cable choke with a manual one due to sticking early on, as well as ditching the vacuum petcock when I got an IMS tank. Think of this as an easy "Stage 1" step.
The DynoJet kit is only adequate at addressing some of the stock carb's shortcomings and if you're going to go down the path of fettling, then save your bucks towards the FCR carb. IMHO "Stage 2" mods like this are really still a compromise around the BST-40's CV design.
As for "Stage 3", if you fit an aftermarket pipe and perform any airbox surgery, you really begin to out-gun the CV carb. It's then a slippery slope of experimentation unless you commit to a pumper carb as well. I now run a TK alloy pipe with stock header (will have weld ground down when I get it ceramic coated later), FCR39_MX carb (ex-MxRob), open top airbox with Twin Air filter. Bear in mind that this is all bolt-on work without any internal engine mods (cams, piston etc.) or porting/ valve jobs as a true Stage 3 progression would entail.
This combo makes the DR a different bike altogether. It doesn't transform it into a snarling, ill-mannered beast but certainly gives it more of an iron fist in a velvet glove feeling. Starts easy, runs smooth, no more farting at the table and excellent throttle response all the way through the range. Economy has dipped slightly but with the better tractability, I'll be returning to the higher stock ratio at chain & sprocket change time, which will restore some fuel range again. It's been said many times before but the overwhelming feeling is that this is the carb that the bike should have left the factory with in the first place, making it into a true thumper.