2014 Gas Gas 300 - Jetting

[n_green]

Looks like this is my only real option. Had a look at the parts fiche tonight, as well as needing to buy the main clutch side cover it looks like the new bikes use a completely different governor assembly and linkage arm assembly which would cost a fortune to purchase.

[Jakobi]

I'm starting to see the benefit in having access to a spring tester. Anyone know any local shops (non industry related) which would also use them?

I've seen the variance in tolerances/lengths/rates in most other springs. By nature there will always be some variance in them. I do wonder how much though. I haven't had the pri cover off my 2013 yet, but I know my 2010 had no shims in it.

[n_green]

Changed the needle to NEDJ#2, kept 40p, AS 1.3 turns out. 168m.

Rode 100ks on the weekend. 50ks day 1 of super techy/tight single. Very slippery terrain lots of slick off camber root infested trails. Mainly 1st/2nd gears.
50ks day 2 of mostly flowing single, 2nd/3rd gear with some top gear wot runs.

Idle is fine as usual, air screw has noticeable effect on idle.

Off idle still noticeably rich. Burbles and 4 strokes at anything less then 1/8 throttle. Well and truly cleaned up by 1/4 throttle and it's superb from here on.

Pulls super hard from 1/4 throttle. Flattens off right at the very end of the rpm range but I suppose that's normal and I never usually rev it that hard anyway.

Can still feel the hesitation just before it comes on the pipe but it doesn't seem to be as obvious as when I was using the NECJ#3.

The hunt to lean out the bottom end a tad more continues.

Fuel economy - not sure but somewhere between 10.5-11.5l used for the 100ks.

[n_green]

http://youtu.be/UXj2z42NgmU?list=UUj...98OBZkBtBnp99A

[n_green]

So bored this afternoon I got the verniers and compared some straight sections of various needles. What I did was work out where the straight section ends and mark it with a texta. Clearly not scientifically accurate but visually it paints a picture, especially when I compare same tapers/different diameters:

First up is G diameter needles:
From L to R: N1EG, N3EG, NECG, JD BLUE.
ImageUploadedByTapatalk1409740519.095243.jpg

Next is W diameter:
L to R: NECW, N3CW, JD RED.
ImageUploadedByTapatalk1409740605.029676.jpg

Next is W and G diameters:
NE, N3, JD.
The W dia is on the left the G on the right.
ImageUploadedByTapatalk1409740688.011385.jpg

Next after Jakes suggestion we have the W and G diameters again, but this time I have also marked the G diameter on the W needle. It is the lower of the two marks.
NE, N3:



For giggles I got my NECG,H,W,J needles and did the same. Marked the end of their respective straight sections and then also marked where the G diameter would be on them:



Like I said not scientifically accurate but visually it's obvious the straight section on the richer diameter needles is longer then the leaner counterpart.

I found it interesting anyway haha.

[Jakobi]

For comparison, you should also do a crude check of the diameter between the needles where the richer one first starts into the first taper. Like last picture, where you have marked the rich ones should be a G diameter, then at the same point measure the W (which will be on the taper) and see how closely they match.

[n_green]

Good idea.

[n_green]

See above, I edited the post to include the comparison images as per Jakes idea.

It looks to me that there is no doubt the needles all run the same taper from the tip upwards. As you can see the mark for the 'G' diameter is in the same spot on all needles in the same series. And as can be seen especially in the NE needle photo each step leaner on the needle results in a minutely decreased straight section length.

It's hurting my brain trying to think about this but here is what I think the results could mean:

The 'J' diameter needle with its slightly shorter straight section would be on the taper slightly before the 'G' diameter needle is. In theory this means that the 'G' diameter needle should be leaner at part throttle openings then the 'J' diameter needle due to the slide being able to open more whilst still on the straight section of the needle, leaning out the fuel mixture that should only be coming from the pilot jet at this stage.

BUT I think the main jet does cross over from very low throttle openings and the richer diameter needle may actually allow more crossover, as the thinner diameter probably isn't as effective at shutting off the needle jet nozzle at the low throttle openings.

Thoughts?

[@enrico@]

Originally Posted by n_green

The 'J' diameter needle with its slightly shorter straight section would be on the taper slightly before the 'G' diameter needle is. In theory this means that the 'G' diameter needle should be leaner at part throttle openings then the 'J' diameter needle due to the slide being able to open more whilst still on the straight section of the needle, leaning out the fuel mixture that should only be coming from the pilot jet at this stage.



Thoughts?

Wrong.

The taper is fixed so increasing the diameter reduces the straight portion but at the same opening cone of the "J" will be leaner of the straight part of the "G".

Draw a straight line leaning to the right and then draws a horizontal line that crosses, this is the "G".
Now draw a parallel to the horizontal but higher, this is the "J".
As you can see the straight part of the "J" ends before but the diameter is greater until you reach the line "G".

Sorry for my english

[n_green]

Makes perfect sense to me actually. I see what you're saying in that the J needle will get leaner in SIZE then the G on the final part of its travel before hitting its own straight section, but my thoughts are since I would be using a much smaller pilot with the G compared to the J the actual air/fuel mixture itself would be leaner.

I could be wrong but does it make sense? Be good to have my own dyno haha.