Jetting!!! Again and again and again!

[gowen]

Cam, thanks for the idea! I have a 155 laying around, so I will give it a shot today. The surges are only in neutral. If I pop the throttle, it will rev, decrease then rev again, like as if I hit the throttle a few times. It does not do it in gear unless I pull in the clutch with some RPM's. Would you think the reeds could be the cause of this? I checked the reeds a little while back and it was a little opened. So I turned them around. Just a thought...

Thanks for the input and help, I'll give the 155 a shot later this afternoon.

[KXcam22]

Gowen,
  I have always wondered if the surging is caused by the vacuum the huge KX piston must make when you rev then chop the throttle.  Mine does this a bit if I chop the throttle on downhills. Again not sure if it does it in neutral but maybe I'll fire it up in the backyard tonight and see.  Possibly the vacuum is grabbing a gulp of air past/under the slide, maybe forcing the slide up a tad to grab some air?  Total speculation on my part!!  Your reeds should be ok as the engine intake vacuum/pressure pulses will force them to work even if the tips are a bit open.  Not sure what your elevation is.  I ride at 2000'-6000' and mine uses a 155.  I ran a 158 for years (ran great) but the 155 is noticably smoother at 3/4 to full and still a touch rich. Cam.

[gowen]

I just got back from riding with a 155. It is lightly raining here, so it was somewhat muggy. Anyway, you were right, I first warmed it up with the 158 rode it a little and did great. But, was very touchy/over sensitive in the mid range, which I was assuming a little lean. I came back to the garage and switched the 158 to the 155 and then richened the needle to the center notch. Which did wonders in the mid-top range. The surging has gone down, but is still existant.

Let me know if you are having the same issue. It is when the throttle is hit and chopped. It revs, decressed the rev then kinda pops and revs slightly a few times. It does it when I chop the throttle in gear and pull in the clutch too. I will try running a tank of pure C12 to see if it helps. I'm now mixed 50/50 pump/c12.

Thanks, it's coming together finally.

[kawdude]

Those are the type of things I'm hearing.  However, when slowing down in gear the bike d**n near jumps at every pop.  It's annoying as hell and dangerous in the wet stuff.

To me if it's surging, the screw doesn't help but the needle does.. that seems to say that the circuit is lean.  This may be related to the needle, clip position, main jet or float level.  I know that I'm not helping.  

It sounds close...I agree with Cam.

[KXcam22]

Gabe,
   Cool! Getting closer still. You might want to try raising the needle one more spot, to richen the 1/2 range and see if that helps further.  Is the 1/8 to 1/2 throttle transition still smooth?  That part is controlled by the straight section of the needle.  With the 155, as an experiment it might not hurt to try the next richer needle with the needle lowered one spot from center to see how the bike reacts (richens the 1/4 but the 1/2 to full should stay about the same. Cam.

[gowen]

Cam, the 1/8th to 1/4th is very close to smooth. As for the needle, I'll give it a shot tomarrow evening. Your help is VERY appreciated. Also, did you fire yours up to see how it sounded? Just curious.

Kawdude, this is what I'm at right now:

Air screw: 2 turns
Pilot: 38
Needle: CGK (larger diameter)
Needle Clip: 3rd
Main Jet: 155

I'm assuming that your bike is going to get VERY close to mine. Cam is the man for the problem you are having with the surges. It sounds like you need to richen the needle and then fix the powerless problem with the main jet (leaning it out). I'm betting you are going to be close to the same jetting I'm at. But, I know every bike is going to be diffrent. Keep us updated and thanks for all your input!!

[KXcam22]

Gabe,
  On your 1/8 to 1/4 throttle resonse, is it a bit ratty (not clean feeling) or does it hesitate a teeny bit?  I would say that the desired response should be sort of a controlled dial-a-wheelie, lots of power very smooth and controllable (although I guess the EGore porting might influence that). I guess I am wondering if you might be a tad lean on the 1/8 to 1/4 area.  That test with the next richer needle should show it that's the case or not.  For the next couple of tests I'd say try the CGK raised 1 notch to richen the 1/2 to 3/4 area.  Then try the next richer needle lowered 1 or 2 notches from center to richen the 1/4 to 1/2 while leaving the 3/4 to full about the same.  Check your throttle response and see if your surging changes. Let me know how you make out. Once we get your bike working perfect we can gang up on Kawadude and get his dialed. Cam.

[KXcam22]

Gabe,
  I fired my bike up last night but then dogs started barking, babies started crying and wife started yelling.  Will try again tonight. Cam.

[gowen]

Gabe,
  I fired my bike up last night but then dogs started barking, babies started crying and wife started yelling.  Will try again tonight. Cam.

  Opps! Sorry about that. Didn't mean to get you in trouble.

I'll give those needles a shot.

Should I order the next needle down Cam? I have a CGH, CGK, and CGL. Should I get a CGJ?

Dial-a-wheelie. Boy, I love it when the doctor orders wheelies.   My 1/8th to 1/4th does not have much power. But, I'm thinking RPM's. Cam, I will have to get back about that one. I'm not sure. I will tell you that my KX does have a mid-over rev porting. So, it does not hit hard until close to the top. Question though, I did have the timing retarted. (just to the retard notch) would that have made a diffrence? I believe retarding is to the right or clockwise notch.

Thanks Cam, I will get back about the 1/8th dealy.

[KXcam22]

Gabe,
  Since the price and response from Sudco is so good, it might be a good idea to get the CGJ.  My thinking is that you might be a bit lean in the 1/4 area hence the lack of low power.  I'm guessing that you will find you have a bit of a flat spot and that it may even be contributing to the surge symptoms.  Even with your porting a 500 with a powervalve should still have a heck of a great bottom end.  I believe retarded timing should help the bottom end too.  While you are waiting for the CGJ needle, try the CGK raised 1 notch to richen the 1/2 to 3/4 area and see how the upper end response is.  If you have the time it might not hurt to try the 40 pilot back for one run and see if you still get an idle, and better yet a 1/8 to 1/4 improvement.  The 38 is probably the way to go but since you have the 40 it wouldn't hurt to try it with the leaner needle and see what happens. Have fun. Cam.

[KXcam22]

Gabe,
  I was thinking that while you get the CGJ you might as well get the CGI just in case (at least that gives you the whole set for the mantlepiece display). The needles are probably cheaper than the shipping. With the 40 pilot test, I forgot to explain that since the pilot and needle (straight section) overlap at 1/8 to almost 1/2, with the leaner needle it might work ok. Again, if theres no idle then forget it, it is obviously still too rich.  Also, I forgot to ask How does the bike start, hot and cold? Mine is almost always 1 kick hot or cold and I think that may be typical when jetted nice. Cam.

[gowen]

Cam, it starts first kick hot or cold. At first it was quite hard to start cold, but I found that it was the stator pushing low numbers. Replacing the stator fixed it right away. So, no problem there. I'll go ahead and order the CGI & CGJ. They have been great about getting parts here, but I also paid $20 for overnight. Which in this case I'll do the same. They are only $5 a piece which beats $20 a pop from the dealer.

So far, I have it where it idles the smoothest. If I turn the air screw in 1 turn, the idle starts falling. I turned it until the idle smoothened out and then backed it a 1/4th turn.

Cam, it seems that the only way it will not surge is if I turn the air screw all the way in. It will not surge it it does not idle.

[KXcam22]

Gabe,
  That is very good information! Turning in the air screw richens the 0 to 1/4 area.  That is more evidence that you may be a touch lean in the 1/8 to 1/4 area and the next richer needle (CGJ) is the direction to go.  If you are 2 turns out and the 38 idles nice, the 38 is probably the right pilot and the richer needle should fix up that lean area, give you more low power and reduce (or eliminate) the surge.  Cool! It seems to me that you are getting very very close.  I saw your post on the WER damper.  I have never riden with a damper or felt I needed one.  Do they really make that much of a difference! I don't have any dunes or really long fast areas where I live. Cam.

[kawdude]

All excellent information guys.  I especially enjoy the part on getting rid of the surges and I agree that richening the mix via the screw effects it.

So what I understand that to remove the surges keep going richer.  If if quits surging great if it doesn't the 1/8 to 1/4 area of the needle maybe incorrect.  That would explain the surging difference on mine when I dropped the clip to the 3rd notch.  It was surging badly and some knocking.  

Thanks again.

[gowen]

Alright! That sounds like a deal to me! I'll get those needles ordered and hopefully have them here by Friday and get back to you about the status. I'm going to a big local riding area Sunday and will have it worked out before then.

As far as a Steering Stabilizer. I've never ridden with one all my life until now. And seriously, it is a great investment. I ride alot of trails with rocks, ruts, sand, mud and roots type and it holds the wheel in it's place and makes it very easy to control in the rough parts as you don't have to hold the steering wheel or fight it. It is worth it if you ride in places where your front end would make sudden movements (sand/mud) or be hit hard by solid objets (roots, ruts, trees, rocks ect. ect.).

Again, thanks for all the input. I'm betting you are right on about the surging and I hope we get it taken care of.