2011 GasGas 250 Six Days

[john_hinton]

I received my bike jetted for my location, Las Cruces, NM and it ran perfect for the first couple of months. Once the temperatures warmed up I needed to lean it out. Las Cruces is around 4000 ft elevation.

Stock Jetting:
180 Main
42 Pilot
7 Slide
N1EF Needle
38mm carb

As arrived (Dec 2011):
175 Main
40 Pilot
N1EF Needle - 2nd Clip position


The bike ran great until Apr and then I needed to change jetting. I decided to change for higher elevation.

I did a ride in Cloudcroft, NM with the following jetting - Elevation around 9,000 ft.

168 Main
38 Pilot
CHN Needle - 3rd Clip Position

The bike was way too rich on this ride in April 2012.

I made a trip to California to ride at Kennedy Meadows and made the following changes to my jetting (Elevation 8,000):

168 Main
38 Pilot
NEDW Needle - 4th Clip Position

The bike ran pretty good, but did not have the snap/life that it did with the N1EF needle. I was suprised to see that my sun/rain switch did nothing with these settings.

I did much more riding back in Cloudcroft, NM with the following jetting which was very good, but did not have the power of the N1EF needle. The power was very smooth and provided great traction (Elevation 9,000ft):

168 Main
38 Pilot
NEDW Needle - 3rd Clip Position

It is getting late in the year and I decided to change the jetting for Las Cruces and went with the following (Elevation 4,000ft):
170 Main
40 Pilot
N1EG Needle - 2nd Clip Positiion

I was so happy to ride my bike with this setting, because the bike was back to new as far as power goes. I could lift the front wheel at anytime and it was just fun to ride. My sun/rain switch once again made a difference.

My question is what do I need to do at higher elevation to maintain the power that I am getting with the N1EF/G needles. I like the smooth power that the NEDW provides, but it feels like I am very lean with the pilot.

Thanks in advance for your assistance,
John

 

[Jakobi]

The NEDx needles are lean on the first taper which gives that nice clean power delivery at low throttle openings. In saying that though you are probably lean on the pilot circuit. You went from running an F diameter needle with a 40 pilot to a W diameter with a 38 pilot. Thats 3 steps leaner on the needle diamter, and 1 steps leaner on the pilot. Essentially 4 sizes leaner! You wouldn't do that with the N1EF. Its also very similar to the N1Ex from 1/4 throttle through to WOT so you are probably running too rich through the mid range due to clip pos 3 or 4. The main might be alright for altitude.

You can either try leaning the stock needle out to clip 1 for altitiude, along with dropping the main. If its just the off idle thats flat on the NEDW, try either a larger pilot, or a richer needle diameter. IE NEDH/NEDG.

Assuming a 38mm carb, running in high temps at your alititudes I'd imagine something like 40 NEDW#2 168/170 would be closer to where you want to be. Being rich will be slow revving but sound wet. Leaning it off will make it crisp and snappy, but going too lean will lack balls. Really lean will hesitate and bog when trying to give it throttle.

 

[john_hinton]

Jakobi,

Thanks for the feedback. When you suggest 168/170 NEDW #2 40 Pilot is this for 4,000 ft or 9,000ft elevation?

I have been reading many of the jetting posts and understood after the fact that my pilot was to lean with the NEDW needle. I believe that is the reason that I was having problems with the bike bogging and not running right.

If you have a suggestion for jetting for both elevations it would be appreciated. I currently have a N1EF, N1EG, CHN, NEDW, and NEDJ needle on hand, plus every pilot and main to go up and down several notches.

For the jetting experts this stuff is easy, for me I struggle with every change that I make. I understand the basics, but all of the needle talk keeps me guessing.

John

 

[GMP]

That CHN needle is for the Euro cat pipe and has no place in a US bike, way too lean.

Try a JD Red or N3EG. I'm not a fan of the NED/NEC series at least in the 250. Too lean and flat off the bottom. Perhaps they are better at altitude, but then there is less power to manage anyway. I'd rather jet a bike to produce the most torque, and if its a bit snappy manage it in other ways like using a G2 throttle. Is the head modified for squish correction? This is a big step forward. Also, I have had excellent results dumping the pig Stealth and going with a straight through silencer.

 

[Jakobi]

I have to admit I have done very little testing with the NEDx needles in the 250. Done heaps in the 300 and found good results. The particular carb on the bike makes a difference as well as all the other variables.

The main thing is to have an approach and not just change things willy nilly. Start with the pilot circuit and work our way up. I wasn't really making any eduicated suggestions, just highlighting that you have basically gone richer clip position wise when you really wanted to lean things out.

I second that about the head mod. Makes a huge difference!