Jetting alternative wanted
 

On my 300/2018 I run the JD Kit in the 38 Keihin.

I have the feeling, that it is a little bit lean in the second half while its fine from zero to 1/4 throttle, but after that its a bit too lean in my opinion.

Currently I run: MJ178, Clip 3, red JD needle, PJ42, AS 1.75 turns open. Temperature 82F, Altitude 600 ft

Is there a known alternative to the standard N1EF needle? Its good once the throttle is at 1/4, but down low I dont like it.

Any hints/tricks appreciated.

The 3 guys I know with 2018 300's all use NECW I beleive.All of them have had their heads recut too.My bro gave up on his 250 '18 , and just bought a Beta 300.
All the 300's seem to run great now ( although they ran fine before too!!)

The JD needles do lean off a lot towards WOT. Throw a bigger main jet at it.

Their red needle is a H diameter from memory. N3EH#3 178 with the same pilot will make for some aggressive power.

NECW is a good choice for nice linear delivery. One step leaner on the diameter for clean delivery off idle.. and just builds. Similar in profile to the N1EF once past the first taper.

Thank you guys!


I have a cut head too. The JD kit works well, the transition from mild to wild is too aggressive and caused by a lean mixture.


Would the bigger main jet enrichen it in the middle aswell? I have a 182 in my parts box I could try (currently running a 178).

I'll get a NECW needle too.

Thanks again
Doc


edit: ordered the NECW, will receive it probably Thursday next week :-)

I have the N1EH in my GP at the moment. Very cold and sea level riding and it is great. A little thirsty on fuel compared to the NEDW but starts better and never knocks, even when stuck in a gully with radiators about to boil.

Jakobi, Second half of the needle looks visibly leaner than the NEDW. I should mic them up and see.

Cheers Keg.. I haven't laid them beside eachother for a long time. I'll have a look today at some point too. The N3 needles are very thick right through to the point in comparison to both the N1 and NE series.

Hey guys. Since the needle runs down the guts of the main jet, main jet size will affect the overall jetting from bottom, mid and of course top. No harm in trying one size up or down and see how it goes. My 18 250GP is running NEDW 3rd and 185 main 42 pilot, stock head, running great, fuel efficient and clean. For an 18 300 std gas gas Australia recomends NECW 3rd, 42 pilot and 175 main. Goodluck with it.

The needle doesn't run down the main jet.. The main controls the flow of fuel into the emlusion tube/needle jet.

See image courtesy of Dansmc
http://www.dansmc.com/carb6_7.jpg

For a crude test to see how much influence the main has over the range of throttle positions you can simply take it out and go for a ride.

This jetting is for all purpose or only for technical terrain? I want to change my N1EF needle because i think my 18' EC300 is knocking in half throttle because of it and i'm looking for the best jetting. Here in my area(Portugal) we don't have to much elevation, is about 0-500m and i have all types of terrain, woods, deep sand and fast open roads. Could you help ? thanks

Fabio,

IMO both needles could be considered "all purpose", it's really personal preference.

The NECW is not as "lively" - smooth and linear, as others have said. So to that extent, it may be better suited for technical terrain - but it depends on the rider. I like riding the technical stuff, but prefer more of a "hit".

Something like the N3EH will be more aggressive, but I find that to be more fun, especially in sand or open terrain.

Jacobi has given the two of the most popular jetting options below:
42 pilot/178 main with N3EH (or variant - N3EG or N3CH)
- or 40/175 NECW.

From what you've said about where you're riding I'd suggest you start with the N3EH.

Let us know what you think!

Jeff

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Jacobi's recommendations above are good ones -

N3EH#3 178 with the same pilot will make for some aggressive power.

NECW is a good choice for nice linear delivery. One step leaner on the diameter for clean delivery off idle.. and just builds. Similar in profile to the N1EF once past the first taper.