Noob question about fuel injection

Just got my newly acquired '07 up into the mountains for the first time and found it to be much more intimidating in the very tight stuff than I expected. Specifically, the transitions between on- and off-throttle were so abrupt and dramatic that I had trouble maintaining my concentration on other factors, like line selection. Everywhere else I rode this bike, I loved the hard-hitting low-end grunt and I've always appreciated the engine-braking on twins. I've had lots of other sport bikes, but only one other with fuel injection - a Suzuki TL1000S a little over 10 years ago. That bike had a similar problem, and it was enough to ruin my fun (I wound up fleeing to a CBR600F4, but then missed the big-twin experience so much I came back to a SuperHawk).

My SD's previous owner installed FMF Apex slip-ons, MH airbox (SAS and O2 sensors removed) and a PCIII (with custom mapping), along with a softer sloping throttle cam. As far as I could tell before this last outing, fuel metering was very good all around. I didn't detect any of the low-rpm surging or other misbehavior I'd read about on stock SD's. It wasn't until I was dealing with on/off throttle transitions during multiple series of tight corners that I had any complaints, but then it was really bad. Is this something that can be addressed with further modification? Does this indicate the need for better mapping? Would the MH secondary butterflies help? Do I need a slipper clutch? Obviously, I'll be practicing my throttle control to minimize my own contribution to the situation, too.

On the positive side, the SD's handling was magnificent -- as you all know already!

Thanks in advance for your input.

I maybe reaching here - but I'm gonna guess that pretty much everyone on here has had if not the same, nearly the same experiences. I'm guessing, that with that set of mods, the bike has already been re-mapped. With TuneECU (free, but please donate!) - you can determine this.

Otherwise, what you describe is part of the charm. Japanese I4 600s they ain't. Not even close. That low-end instant-on torque punch is part of what makes the bike so much fun. Bike wants to lift out of every corner effortlessly - tee-hee.

OK - while these things are an acquired taste (read: not for everyone), use a lower gear(s) maybe; keep the revs up. Less braking needed on the entry just by lifting, and don't lift entirely - keep some maintenance throttle through the turn. With more revs in, its easier to control the throttle. After the apex - bring in as much throttle as quickly as you dare. Word of caution: Extreme euphoric giddiness can occur, followed by desire to repeat the experience as many times as possible. Not unlike your 'ol TL (desmoquattro, etc.), if you ride it like it was stolen, it seems to work better.

Remove the secondary flies AND shafts... Huge difference in smoothness and good for 3-4 extra hp according to the dyno of one of the members here

Many thanks for your input. Sounds like removing the secondary flies and shafts is what I need to do. But I thought they were supposed to smooth throttle response, theoretically at least. Why would KTM go to the trouble of including them if there is only good effect from removing them? I'm not arguing against removal - I'm just curious why the effects are opposite what the marketing says. Other problematic items have "benefits" we simply consider irrelevant, like fuel economy or emissions, so we get rid of O2 and SAS. Surely there was some justification for the secondary flies, even if we prefer to do without them.

I already planned to get TuneECU and get rid of PCIII to reduce layers of electronics. There would be no advantage to retaining PCIII, right? I'd rather spend a little more and not have to build up a TuneECU cable myself. Any recommendations on a good source for a ready-to-go cable?

Thanks again!

people think removing the secondaries is some kind of miracle cure. its not. you have to learn to ride this bike. its a big twin and has a huge amount of engine braking, keep the throttle cracked always in a corner.
if you just remove the secondaries and not understand the power delivery you still arent gonna like it (secondaries have nothing to do with engine braking). if you didnt like the TL you probably arent going to come to terms with this one which is a shame. give it some time and learn the bike before you slam it into the turns for your own safety!

what does in fact help with the abruptness is keeping a couple of fingers on the brake lever to have a common reference, it smooths out the throttle movement which can throw anyone by hitting a bump which will telescope any movement directly to the throttle. also relax your arms, if they are rigid youre gonna have the same problem, try to relax and let the bike do what its gonna do. ive been riding for 30 years and these 2 things made the bike much more fun, after a while (unless your tired and forget...) youll adapt and love the thing.

I continue to appreciate everyone's input. In case I wasn't clear in my first post, I already love this bike and chose it specifically for the thrills only big twins have to offer. I've had several other v-twin sportbikes in the past, and they've always been my favorites. With my old TL, I enjoyed it immensely in many riding situations, but I was doing a lot of tight/twisty riding and found the on/off transitions so choppy that it detracted from the fun. I associated this more with the fuel injection than with the engine configuration, although obviously grunty twins are going to compound any such difficulty in the fuel delivery. I've never had this issue with carbureted engines, big v-twins included.

My only complaint with the SD is the extreme intensity of the on/off throttle transition when I'm dealing with a series of tight first (and occasionally second) gear corners. I will certainly be working on better throttle control, including trying to avoid ever being all the way off the throttle if possible -- I even look forward to the challenge. But I also would like to reduce this problem through whatever mechanical means might be available.

Again, thanks for all the input. I just didn't want anyone thinking I was sour on my new machine -- far from it!!

And, BTW, I found a good source for the TuneECU cable (already put together):

http://www.dualsportwarehouse.com/CJ-De ... -C-KTM.htm

(I just hadn't looked closely enough at the TuneECU postings here when I asked the question yesterday.)

Ordered TuneECU cable today. We'll see how it goes after I've had some more time to acclimate, remove the secondary flies and play around with the mapping.

To be continued, I'm sure...

Try a 17T front sprocket to, much better in the twistys, more speed range in each gear and smoother coming on the throttle

I run 17/39 gearing now which is perfect for my SD...............

Oh and please dont knock the TLs, I love mine, well sorted the TLs is better than the SD mid corner and on the exit and will suck the paint off any SD/SDR

Thanks for all the ongoing input from everyone.

TLS_Russ: As for the sprocket suggestion, I thought the stock front sprocket was already a 17T, and the stock rear is a 38T. If you're running 17/39, you've actually made the gearing shorter, which should making it even more aggressively sudden and abrupt. Did you mean to say you switched your front to an 18T? That would tame the hit somewhat, I'm sure, and deliver a wider ranger in each gear, like you mentioned.

Oh and please dont knock the TLs, I love mine, well sorted the TLs is better than the SD mid corner and on the exit and will suck the paint off any SD/SDR [/quote]
Your SD must be running really bad?