Playing with jetting - EC300

[Bailey28]

I have had the chance to play with two new needles in my '10 300. This morning, I put in a CCL, 42 pilot, 180 main, and 1 out on the air screw. The bike ran great, it was smooth all over with plenty of bottom end. It felt a tad lean coming onto the main so I wanted to try a needle with a steeper taper.

I got an CCL in my order to play with. I set up:

42 pilot
ECL 3rd clip
180 main
1 out on air screw.

Wow... The engine was super electric from idle and into the midrange. It had a little more hit going into the powerband especially in deep sand if you touched the clutch. No four stroking or pinging on the low end at all. None. It sounded crisp. I wound up at 1 3/4-2 out on the air screw and could probably drop to a 40 pilot.

The main I found interesting. The 180 I started with was way too rich and the bike wouldn't rev out at all. I switched to a 170 main and it was alot better. I could probably go to a 165-168 as the E taper needle is really thin down toward the lower part. It is as thin or thinner than the stock N1EF.

I will report back with more findings on the E taper soon. I could literally ride at walking speed in 1st or 2nd gear at idle and crack the throttle open slightly. The bike would just start pulling from nowhere. Smooth. No crackling, pings, bogs, hesitation, it was trials like. On either ignition map the bike ran that good. If anything, I want to make the hit smooth again. Don't misunderstand, the hit is not violent but it seems that it is accentuated slightly more than with the C taper or the N1EF. Then again it may be that the bottom is so electric that it just feels that way.

Some of the other needles I have now: BGL, CCK, CCL, DDK, DDL, N8HG(ok)

Today's weather: 70*F Sea level,
fairly humid.
43:1 Repsol 2T Sintetico
93 octane pump gas
NGK BR8EG
LTR powervalve cover
GG stock pipe
#7 slide
Keihin Air Striker 2, screw on black round top

 

[john01]

Did you mean to list the CCL twice or was the second one you tried something else? So you tried the CCL and a ECL today?

 

[Bailey28]

I did the unthinkable and bought a bunch of needles. I went through roughly the same experimentation with my old KDX, and I thought it would be interesting to see how smooth I could get the GG motor.

I stayed with the "L" root diameter as the N1EF is the same as the L diameter on the Keihin three letter aftermarket chart. I didn't want to change too much at once. I kept the same diameter so that the pilot jets could be kept in close range as well.

The CCL was great, but I think the ECL was even smoother. That is correct, the E taper. I had a DDL with me but the E taper ran so good that I just kept riding to continue to test the E today. I put the E in after the C taper to feel a more drastic change between the two to see if I like it. I will do more tinkering tomorrow and Sunday provided the rain holds off. I think I can get the bike even smoother transitioning into the midrange. Right now, it does not blubber, anywhere under any situation. It does not load up either.

The spark plug was mocha brown with the first three threads black. Before I take the E taper out to experiment with one of the others I will tinker with the main jet size again, probably go to a 40 pilot, fiddle with the air screw and maybe the clip position. I may set the float back to 16mm, right now I lowered it to 13mm as it was leaking out of the overflow on the sidestand. I don't have any other mods except for the LTR powervalve cover.

 

[Bailey28]

Did some more testing today, rode my friends sand track. I like the ECL in the fact that it is super smooth from the bottom into the mid, however the taper is too aggressive and kind of floods the engine with fuel past 1/2 throttle. I tried a 180, 175, and then a 170 main.

I was hesitant to go lower on the main because the bike is new and I don't want to buy a piston with 10 hours on it. The spark plug porcelain center electrode was light tan and white, with three black threads. The top ground strap was purple with a light hint of white ash on it. The expansion chamber also developed a purple color to it, right after the first bend.

This is funny because it is so crisp on the low end. However when I get out of a tight section and you think the power is going to kick in, it just four strokes and won't accelerate any more.

I will switch back to the CCL or CCK needle 40 pilot 175 main here in a bit.

 

[GMP]

Be careful before you seize that thing. I guess the 300 has enough juice off the bottom to still pull good when lean, where the 250 will go noticeably more flat before the obvious lean symptoms show up. I did the same thing with a KTM300 some years back trying to clean it up, thought it ran good but had white ash at the end of the silencer.

Search user name "pobit", he did a very good assessment on several needles in both the 250 and 300 with the original AS carb.

 

[Bailey28]

Thanks, it pulled really good on the hard packed track and trails. I guess the loam is where I noticed it struggling a bit. The motor just sounded flat with a low buzz. It would come onto the pipe hard then start sputtering as the E taper was dumping in too much fuel mid and top. This made it hard to ride.

I went back to known good settings: 40 pilot 175 main CCK-3 1 1/2 out on air screw. I will try this when I get more premix made up in the morning.

BTW, I had no spooge or smoke at all with the E taper, not even during warm up. I am absolutely sure I mixed the fuel at 43:1.

 

[widebear]

Thanks, it pulled really good on the hard packed track and trails. I guess the loam is where I noticed it struggling a bit. The motor just sounded flat with a low buzz. It would come onto the pipe hard then start sputtering as the E taper was dumping in too much fuel mid and top. This made it hard to ride.

I went back to known good settings: 40 pilot 175 main CCK-3 1 1/2 out on air screw. I will try this when I get more premix made up in the morning.

BTW, I had no spooge or smoke at all with the E taper, not even during warm up. I am absolutely sure I mixed the fuel at 43:1.

Which clip position on the e taper?

 

[Bailey28]

I had it on the middle or third clip. I was going to try and raise it so it was not as lean on the bottom into the mid. However if I did that I would imagine that I would have to go to a 158 or 160 main jet due to the very steep taper.

The E needle is about as thin as the N1EF at the bottom however, and folks here running the N1EF are around the 172-180 range on the main. The E taper made the bike lean at idle, off idle and into the lower mid but it pulled ok, and was crisp.

In the midrange, the bike seemed to wake up and hit hard. After that any further throttle opening would make the bike fall on it's face by crackling, four stroking and losing power and refused to rev out. If I let off the motor cleaned back up.

I am at sea level mid 70's for temperature. Like I said in another post, I tinker a lot and bought these needles for comparison purposes. I don't want a seizure however. I would guess that the E taper would run good with a very tiny main but I am too chicken to try it!

 

[widebear]

I would'nt be to worried about the main jet size with the e taper, it is after all the inter relationship between the needle and the main that is of more importants. If you plug readings are good at wot, carry on. Are you using a proper plug magnifying light for you readings? If not you should be because its the best tool you have. All that being said if you like the low and part throttle response of the e taper you can try a 2000 kx 250- N3YF with a 172 main. It might just be what your looking for.

 

[Bailey28]

Thanks Widebear,

I think I am finally figuring out what the OEM needle option codes are. In N3YF the N is the needle style/type used in our carbs in general, the 3 is the specific taper, the Y is the L1 and the F is the diameter on the straight portion.

So the N1EF and N3YF are the same straight diamter but different in taper and L1?

I really wish someone would come up with a one page handy OEM needle chart that compares only the OEM needles. It would be like the Sudco needle chart for the aftermarket three letter needles.

I looked at Ron Ayers.com and they list all the needles for the KX250. They keep the "3" taper throughout. However they change the L1 between Y and W, and they change the diameter between D, E, F, and G.

http://i264.photobucket.com/albums/ii174/hallsy_album/002-3.jpg

I found this and can see the N1EF on here if I look for the F diameter at 2.705mm.

 

[TNT Cycle]

I think just like any jetting thread there are so many variables. My '10 300 was all over the map as Ive said before. It was great in what I would call WOT likely 70-95% from idle to high revs in one motion. Generally rich on bottom any throttle position. Lean in the mid most times. Generally rich up top. It would get crazy lean if revved and then thottled back to slow or maintain a speed on trail and rolled back on power.

I thought stock needle started lean and had so so taper for motor and had idiot proof over rich finally taper. All of this compounded problem on my bike. It was kind of different every time you rolled on the power depending on initial rev, starting throttle input, and new throttle input. Some days it seemed to run fine. I never put a ton of effort into jetting on other bikes but read here and did my own thing. I work at shop that can get parts from most anyone. Marshalls Distributing sells needles from sudco that retail for about $7.99 cheaper with my I work here discount and no shipping like if we order from sudco. Now they don't have every taper so I pick CEJ after looking over charts. I picked a few others also, would have to look at them to remember. CEJ has been awsome for me and never used others. Plugs look great and smooth with excellent control.

Mine loves to have lots of fuel on bottom, I wouldn't call it rich. But I think there are tons of options out there if you are willing to try'em out...

Ohhh mine is an ASI, #48 pilot, 178 main, clip position 3

Cheers,

Rick

 

[GMP]

This is very very close to the original LTR needle and setup that Les developed on Jeff's 300 awhile back, and has worked well on a lot of 300s since.

 

[Bailey28]

OK, so you guys are saying try CEJ clip 3, 48 pilot, 178 main.

The J is one step richer on the bottom from the K and the 48 is three pilot jets richer. What air screw position are you using?

BTW, I tried the CCK, 3rd clip, 40 pilot, 178 main. The bike runs good although it blubbers a little bit on the very bottom. Under load it does not blubber but just getting on the gas after a slow corner I can hear/feel it.

I may raise the needle to clip 2 to see if I can limit the blubber. Still not too much smoke and hardly any spooge at all. The plug was dark chocolate brown.

 

[GMP]

300s are naturally more of a PIA to jet. If you find yourself chasing jetting much longer, consider going to a leaner slide. #7 is good in a 250, but the 300 is a bigger pump. I had a KTM 300 that was impossible to correct with a needle until I leaned the slide and dropped the signature. A head mod wouldn't hurt either.

 

[Bailey28]

I was doing some reading on changing the slide vs. changing the needle diameter. Most articles said it was easier to change the needle ($6) vs. cutting or changing the slide ($60). This supposedly accomplished the same thing. I wish I had a #8 slide to try out for comparison sake.

I bought a bunch of needles to start with and I kept the diameter the same as the stock "F" at 2.705mm. For the aftermarket keihin 3 digit code needles that translates to an "L" at 2.705. I figured if I wanted a much leaner idle and 1/8" throttle I could go thicker with an M,N, P, or Q.

I thought the bottom end was really clean with the ECL I tried. Some sites list the Yamaha N3EW as a good needle for smooth powerful bottom end. The Yamaha N3EW clip 2 is the same as the same as a CEL clip 4. I have a CCL, so it would be CCL clip 2. I know there is another taper in the Yamaha needle but for bottom to mid they compared the two.

I need to buy excel to run JD's needle coding charts. Then my wife would complain that I sit in front of the computer too long!

 

[widebear]

Re bailey
( I was doing some reading on changing the slide vs. changing the needle diameter. Most articles said it was easier to change the needle ($6) vs. cutting or changing the slide ($60). This supposedly accomplished the same thing.)

Absolutely incorrect!, unless the throttle cutaway is allready very close. It's like saying you dont need to wear pants just put on a bigger shirt or longer socks instead. I've got a really good mikuni graph but dont have a scanner. I will however get around to it.

 

[Bailey28]

Awesome, thanks. I guess I'll pop for a #8 slide from JD along with the needle chart.

 

[widebear]

Ron Black will cut your existing slide for $15.00 which I think is a smokin deal.

Just as a point of interest I finally had a chance to try out the 011 xc 300 with my tried and true jetting that has worked on every gasgas I have ever owned be it 200,250 or 300. I know the new bikes are a little different so I established a baseline using a proven solution starting with the squish mod. As a jetting starting point and honestly expecting nothing special I went. 35, pilot #9 cutaway, N3YF needle and 172 main. Perfect!

 

[Skidad]

Ron Black will cut your existing slide for $15.00 which I think is a smokin deal.

Just as a point of interest I finally had a chance to try out the 011 xc 300 with my tried and true jetting that has worked on every gasgas I have ever owned be it 200,250 or 300. I know the new bikes are a little different so I established a baseline using a proven solution starting with the squish mod. As a jetting starting point and honestly expecting nothing special I went. 35, pilot #9 cutaway, N3YF needle and 172 main. Perfect!

$15 is a great deal for a slide cut from RB Designs (plus shipping 2 ways of course) but once it's cut there is no going back. Personally I would pony up the money and just buy a #8 slide (or #9 even...jeeez widebear) from JD Jetting as he has a very good price for the slides. It's nice to have a bunch of different slides to tinker with and they can make a big difference in low speed performance.

Want to complicate it even more....there are slides with a little notch in them and slides without and that notch can also make a difference

Widebear...does your #9 slide have the notch in it?

 

[Bailey28]

I recall sending Ron my carb off of my old KDX some years ago. He recut the slide to a #7 from a #5, CEK, and did the divider plate mods. I never took the head off but the carb mods were great.

I still had some issues with the pilot and bottom end jetting but I sold the bike before I sorted them out.

Widebear, that combo sounds even leaner than my ECL-3 42/170. I rode the CCK-3 40/175 this weekend for a short ride and it was good, but not nearly as clean as the ECL needle. I think I may try the CCL-3 40/172/175 this weekend and play with the air screw a little. I even bought a CGL, but I don't think I want an L1 this long, or have to use it on clip 5.