Mmm... aww alright then... time to "RTFM" again... Yep Thanks, just found that as well.... and this one too: [thread=469753]469753[/thread] I'm probably getting a bit ahead of myself and committing the cardinal motorsport sin of trying to change too many things at once. (I have Dr Freeth's voice whispering in my ear...) So i'll start with clean and sort the stock carb.. then remove EPC and SAS and see how that goes... and then... consider drilling the slide holes (but after reading this maybe not... ) and consider rejetting or playing with needle height... Although I do find it interesting that the uber-expert on stripping, cleaning & modding a BST40 says this: http://www.advrider.com/forums/showpost.php?p=7095109&postcount=9
Same as the DR650 BST expert (mx_rob). Found the limits of the BST, went on to the FCR39mx and now fuel injection...
I think you'll need to throw a new exhaust can in the mix too just to really confuse things A free breathing can, vented airbox & a properly jetted, drilled slide BST40 is quite a noticeable improvement over stock. You have until the weekend - we're going to check out the Waipunga access for the MMMMM if yer keen. Cheers Clint
Yep, I also want a lighter & freer-flowing can at some point. I guess my point is, why spend time and money improving the BST when even at it's best an FCR is still better. Around $200 2nd hand on ebay... I wan't a bike that runs really sweet and pulls cleanly at low/mid revs with snappy response. I think thats probabaly easier to acheive with a smaller carb, as it will flow better at those volumes. It's been a while but memories of popping monos my old XR500RE still brings a smile to my face. I want that kind of performance again... Although I must admit I was pretty impressed with your bike, so If I can get mine to run as well as yours i'll be pretty happy. Damn.. would love to, but doubt I can make it.
This guy? http://www.mxrob.com/FCR_Install.htm Interesting read... all reports I've seen/read so far tell about the great things an FCR39 does.. but no-one seems to talk about what it *doesn't* do.. Oh yeah, cycletreads have FCR's advertised on their web site. for $1,500...
The only downsides I've heard of is that a little more fettling is required to get good fuel economy than with the BST & they don't deal with altitude changes so well (not a problem in NZ usually). However Rogerh's 640E is a good example of what is possible with the FCR (I think his is a 41) it pulls well & uses the same amount of juice as mine. It's not $1500 better but maybe $500 Cheers Clint
See this thread for some local info on removing the sas & epc: Fixing the 640 base gasket, and more... Later I uncorked the bike, fitting a cored USA OEM supertrapp muffler, performance airbox sidecover, 160MJ and drilled slide. Then I removed the snorkel as that seems to be indicated for high-flow heads. I tried moving the needle clip initially but it was stall-prone, standard pos 3 works fine. Definitely more grunt at lower revs and well worth doing, can't speak to fuel consumption as have only really raced it & trailed it, done bugger-all consistent road running. I don't care if the drilled slide accelerates wear on the slide & needle jet - they is gonna wear out even with the OEM configuration - monitor & fix when the need arises, ride & enjoy. I would venture to suggest that setting up the BST properly (cost: one MJ, plus one emulsion tube if worn) and spending the rest on tyres is a better bet for an adventure bike. I only really want the extra snap of the FCR on very technical terrain when I have non-DOT full knobblies to put it to the ground. Racing endurocross was when I REALLY wanted the snap of the FCR. Note that Nordie's FCR-equipped DR650 feels lovely and crisp and pleasantly responsive... for a DR. Strongly recommended mod for that bike.
And Warewolf's 640A feels nice and responsive for a paint shaker. Feels like the counter balancer is out a couple of teeth. The FCR makes the DR nice and smooth through the bottom and mid range. To get any improvement up top requires a new cam however. Also I suspect the KTM's don't use 33mm intake & 28mm exhaust valves... I would not like to go back to the BST as my riding is done down low and through the mid range.
I finally pulled finger and removed the carb. Yeesh.. what a fiddly/crappy job getting it out. I had to drill the float bowl screws out as they had seized and weren't going anywhere. I stripped the carb down and had a gander... nothing to write home about at all.. it all looks pretty good except for the scratches in the slide. The plastic insert had thin film of pasty gunk on it. The only other thing of note was that the TPS was cranked around (anti-clockwise) as far as it would go on it's slots. Which means even when the throttle butterfly is fully closed the TPS would still read ~1/4 open... I have Noooo idea what effect, if any, that would have. I left the bits soaking in some carb cleaner yesterday, (but pulled them out overnight) and will give it some scrubby scrubby tonight and take some close-up photos. In other news, I found a wrecker in Oz with FCR39's for $495 Aud, which is more than I had anticipated. I was hoping $200-$250 for a 2nd hand one as I have seen them on ebay for ~$200US. Oh well, i'll keep soldiering on with the BST40.. and keep my eye and ears open.. I might get lucky one day.
So then... The parts diagram isn't particularly useful in telling me where I would find the 2nd and 3rd microswitch used by the EPC gubbins... From a previous conversation, I thought id find one of them hanging on onto the carb itself. If the diagram below is to be believed all three switches (part no. 30) should be in the same neighbourhood. Correct? Are all three hiding under the sprocket cover?
Yep. on the end of where the shift drum is. IIRC the neutral sender one sticks straight out, the 2 anti wheelie ones go in on an angle. I used M10 cap screws with lashings of loctite to fill their holes. Cheers Clint
I just disconnected the wires from them, and ended up releasing the connector pins and pulling the wires completely out of the harness (ie all except the neutral switch wire).
Well that didn't happen... mebbe tommorrow.. if i use a cap screw is there any risk of using one too long/short and ker-pfaffing anything? I think i might follow Colins lead on this, but i'll swap them around so I have a working neutral light.
Don't think I have written this all in one place before, so for what it is worth.... BST40 as it comes std is choking the bike With the mods, there is an improvement that is well worth doing, but the biggest improvement is from a more free flowing can, and opening the air box. This "free flowing" and carb set up is what had the biggest effect on the vibes on my bike. Reduced them significantly. (but it is still a paint shaker . And I don't care. But I believe this is a big part of the reason for the wide variation in these bikes) I brought an Acropovic can, and KTM recommend a larger main jet, and the open airbox side to go with this. I just followed their recommendation, and it all worked a treat. If someone used the SXC can, I would suggest following the same recommendation that they suggest for the Acropovic. I just found this recommendation in the on line catalogue's, (at KTM USA site) associated with the detail for the Acropovic pipe. It is interesting to note, that these instructions were not mentioned with the pipe fitting instructions. I did the pipe, carb mods, and open air box mod separately, and the pipe was the best improvement, but I ended up leaving them all on, as I liked what they did all together. This was a major difference from stock, and well worth it. Then a few months later I tracked down an FCR39 from the US. KTMTalk classifieds seems to be the best place to locate them, but the flea market here is worth keeping an eye on as well. The 41 is good, and the best bet if you want the most improvement at the top end. Seriously good for supermoto use. This is what comes standard on the SXC bikes. My objective however was to get better low to mid for off road. The 39 works better for this as the air velocities in the carb are higher at low speeds, and give better low end response, so the 39 was my preference. The 41 will make a bigger difference on the road. Mine was a MKll carb, and fit pretty much straight in. I should have changed the intake boot as well, but once I got the carb, I was just impatient to get it in. For jetting etc, I used the standard settings for a 525exc (which is what my carb came off), and these work fine as they are. Heck of a lean needle, but well covered by the accelerator pump. It is worth taking some time to set all this up before you fit the carb, as it is a bit of a pain to get in and out. Accelerator pump is important to get right. The 39 IS worth it. This is a much bigger step up than the BST mods. I would not say the bike is faster, but it is certainly more responsive. Think fun. Lots of it. $1500, maybe, but it is better to find one at a reasonable price, then you will be very sure it is worth it, and happy with the bargain. Patience will pay off. I have seen them on trademe for about $500 at times. With fuel consumption, the BST was very consistent. Went onto reserve at plus of minus about 3km no matter how you treated it. With the FCR, if you are nice to it, I got 10% to 15% more kms until reserve, and two up, and dirt riding on the seal () you can get it to about 10% less. The FCR just uses the fuel more efficently. It is a really good carb in all respects IMHO. And did I mention that at higher revs, the induction noise is just intoxicating.... Inviting WOT.... You get the picture. Be prepared for more chains, tyres etc. Hope all this is helpful for someone. Let me know if there is anything I can add.
Just make sure they're shorter than the sender. Models sold without the EPC have nifty low profile cap screws there so if you wanted to be real fussy you could look them up on a 625SXC parts list & order some of those, every gram counts Cheers Clint
Good info, thanks Roger. Sounds very tempting to go to an FCR for the extra kick. That's not my experience. Mine is quite sensitive to how it's used. Best of 4.4 L/100km at steady 100km/h tarseal cruise. Typically sub 5.0 L/100km tarseal touring, about 5.5-6.5 L/100km adventuring, and up to 9.0 L/100km with off-road/trail use. So best is about half the worst.