OK....previouslyrunning of 2152 with DJ spring, 2N, 140 mj, 3.5 turns out, lidless and Q4slipon near sea level. Changed to stock spring and 1N


Bikemay have lost some low end torgue from idle to 4,000 rpm. Previously hadhesitation between 5-5,000 rpm. Bike now pull hard from 5,000 to redline. Nohesitation anywhere. Can pull unassisted, sitting near the gas tank, wheeliesin 1st. Sweet spot seems to be 5,000 rpm. In 2nd the front wheel wants to comeup, but remains on the ground. Can do major fishtails in 3rd and 4th gear. Bikefeels like a beast


WOTin third from 3,000-4,500 feels a bit sluggish and then major power at 5,000 toredline. You don't get another rush at 7,000, just steady power.


Thebike also got louder, even at low rpms. Not sure why


OK,klxster....you can now pipe in with opinions

 

Interesting Kevin.. If you like the way it runs now, just keep what you have.. With the troubles you've had, it must be nice to have it just run correctly and be enjoyable.. As a side benefit of your current setup, you are certainly getting fantastic gas mileage when riding conservatively..

Now, about the power levels/throttle response from idle to 4k. It's kinda difficult to explain the relationship between the spring and the clip position - but let me try..

So, here is the scenario for the below analysis. Single track trail, "cruising" the twisties in 2nd @ 2.5-3k rpm, then a snap and hold WOT until 5k rpm for a little straight section in the trail.
The heavier spring gives you "less needle" AND less slide opening - from one milliscond to the next - than the lighter spring - it is lifting it slower compared to the DJ spring.
Now the clip position: Capture a millisecond of the acceleration - freeze-frame it. In that millisecond, a lower clip - say 2N - will have that needle raised slightly compared to 1N, giving you more fueling. Now imagine going forward in time in super-slow-motion and see that the 2N makes the whole needle fueling curve "fatter" than would 1N.

So the clip position determines the fueling curve offered. The spring determines how this fueling curve is "presented". A heavier spring "stretches out" the fueling curve within the range of 3.5 - 7k rpms. Starts it slower down low, and finishes it more gradually up top..

You put the DJ spring back in and you get more slide opening and more fueling at any given millisecond - and WOT fueling(fully raised slide) will begin sooner in the RPM range. You lower the clip to 2N (keeping the stock spring) and you get the same slide action/opening you have now but you'll get a little more fueling from one milisecond to the next.

With a series of repeatable tests for power/throttle response below 7k rpm, and a good dynobutt, you will easily know what your bike wants - less spring or more clip.. Actually, just a good test ride on a trail you know well will tell you..

For what it's worth: The DJ spring will be a "larger" change to your bikes' performance (for better or worse) than changing the clip back to 2N. 2N is more of a little "tweak" to what you have now.

Either change should certainly be noticeable - your wheelie testing is also a good test for this..

 

Could the heavier spring also be drawing out the "fake pumper shot" (giving it more fuel before the slide opening) and therefore alleviating the bogging I was getting at 5-5500 rpm?

 

Well Kevin, I've worked with half a dozen members that experienced the stuttering/bogging issue. The tendency is to blame everything - except the simple truth that if your perfectly running carb becomes a poorly running carb after the install of a known working performance setup, the finger points directly at a flawed reassembly and/or re-installation..?

As far as I know, you are the only one that seems able to repeatably cure stutters/bogging with a carb "re-tear-down".. You have done it twice now - that makes you and your carb "special" and our current best hope for figuring out what is causing it..

This stuttering/bogging is a malfunction. The heavier spring and switch to 1N (from DJ spring and 2N) did not cure your bogging. You had no bogging with the DJ spring and 2N at one point in time. You've cured it (hopefull not temporarily this time) with something you did during the carb session.

 

If you have truly lost some power and response below 4k (and not just that it seems weaker only because the power above is now so "mowah") it can only be due to the fueling being much leaner now, than it was before. And that is tweaked toward "fatter" with a lower clip position or with the DJ spring..


Ok, I'll toss in opinions below - but remember that like pie-holes, everyone has em..lol

Pulling power only wheelies in 1st without the MCM means to me that your bikes' low-mid range fueling is very close to perfect. The smoother 5k-redline power means the spring is creating a more even fueling by stretching out the fueling in the RPM range. As long as this is enhanced power 5K-redline, the spring should stay. The clip should be moved back to 2N for a possible further increase in power/throttle response below 6-7K..

There, my opinion - feel free to disregard..lol

 

Well...maybe I'm getting smarter cause that's what I was thinking as well, putting it back to 2N. Would 3N be too much? With 2N and the DJ spring it only needed choke for a couple of seconds. Now it needs it for 30 seconds, so I was thinking a little lean at idle, and probably to the lower rpms.


Any idea why the bike is louder now? It's not a problem, but I'm curious

 

Being I'm running the same carb setup this is interesting feedback. It almost has me considering dropping my clip to 2N just to see/feel any difference, but I'm going to wait until after the next Dyno test before I make any changes.

I will add that I spent serious time dialing the details around the pilot jet (#40) which made direct impact to my throttle response below 2,500 rpm's. I want to say I'm at 1 3/4's out from slightly seated. I started at 2 turns out from slightly seated and adjusted both lean and fat until idle drop. From there I tested each adjustment between the two until I had the best throttle response. It made a significant difference once all other carb adjustments were completely dialed in first.

Kevin - Are you running a stock pilot jet?

 

Yep, you gettin all learned up and don't need ur hand helt no mo..

Well, I guess you are "getting into" the whole fine tuning thing.. If you're to be a "fine tuner" , I hope you have a good dynobutt and test methods.. I am going to advise and add opinions on possible outcomes - do not let expectations from my opinions taint your assessment outcomes. I could be completely wrong. Just because what I say makes sense doesn't mean I'm right.

Each notch is nearly a full point in AFR. Not important to you except to "learn ya" that notches are to be taken seriously - don't go crazy with em..

IMO, I can "see" 3N being a possibility that should be tested, but not/never 4 or 5N.. Again, at 1N, your bike pulls power wheelies in 1st - and very few can..

Yep, you can go directly to 3N if you want to. The advantage of doing so is that the effects will be more "dramatic" and easily assessed compared to "sneaking it down" to 2N first. If low-mid is not improved (or worse) then you done gone too far.. If the "power hit" returns 6.5-7k, then be sure that it is "new" power and not just that power below this "hit" has been slackened - IMO, the "power hit" returning COULD imply an overly "fat" condition too soon - when engine speed raises enough to support the "fatness" you get a jolt of power..

Using the stock spring and tweaking the fueling curve with clip positions is brand new territory. You and Houstons4 are exploring it for all of us -obviously with great success.. So at this point, I am no longer advocating the use of the DJ spring for lidless performance with NON-MCM+Slipon KLX's. Quite frankly, when I was dyno testing, I did not have the knowledge and wisdom to consider that the DJ spring might be too soft for lidless performance with non-MCM bikes..With MCM, the DJ spring works perfectly fine with DJ140/2N. We will have to investigate use of the stock spring with MCM'd bikes..

You might want to start your own thread about these adventures - rather than bury such important info in this thread.. You have a lot to share - what with the stuttering issue, stock spring and 1N, etc etc..

 

Houston, he is running the DNO228 needle outta the 2152 kit (and a stock #35 pilot jet).. So, a very different animal from your DN0352 needle (outta the 2206 kit)..

Your needle has that thing I call a "fast taper" near its' end. That is the thing we have to worry about with your bike. We can't have that "fast taper" fattening up the fuel curve too soon. I am absolutely sure your needle provides a superior fueling curve from 3.5 - 5K rpm over the DNO228 in lidless applications..

I haven't said this yet - it's still a little too soon in yalls' testing - but there is a very good chance that if low/mid fueling is controlled well with yalls' stock spring/clip setting - more power can be found with bumping the main jet size to DJ142, or possibly(but less likely) a DJ144. A DJ140 shows 13:1 on top (a little lean for max power) - 12.5 to 12.8 (:1) will give more power above 6.5-7K RPM. But less altitude forgiveness..

 

Yeah...I'm running the stock pilot. This is the klxster proven setup for the 2152 kit, but that may change with the stock spring (instead of the DJ softer spring I was using). If I remember correctly, you have the 2206 kit, so that may be the reason for #40. I was thinking about upping to the #40, but will try the 2N & 3N first, mostly because I don't have a #40...but I am intrigued