2016 300RR Jetting - sputter off idle

[Philthy]

I found some good info by searching the forums that I'm going to try, but wanted to get some input on my question in red below.

I ride mostly 5,000 - 8,000' elevation in dry temps 70-90.

I ended up jetting per the manual with 160, 35, N2ZJ-2. First couple rides, bike ran ok mid to high throttle, but noticed fuel coming out the overflow and some sputtering when cruising just off idle. I lowered the float level which fixed the overflow issue, but still sputtering just off idle. The sputtering I'm confident is a rich condition (4-stroking) as it gets worse as the temperatures warm up and/or I go up in elevation. As I adjusted my air screw out past 2.5 turns, the idle kept improving, so I'm rich down low. I dropped the needle to the 1st position and there was an immediate improvement with less sputtering and better response off idle, but still not quite there. There's still some sputtering and for idle/response I'm still 2.5+ turns on the air screw. Note that with the increase in sputtering, I get more spooge out the pipe and vice versa with less sputtering when I leaned the needle. I'm reluctant to go down a pilot jet and think the proper needle is the fix.

So I hear rave reviews of the NECJ needle, but that appears mostly from near sea level people. At my elevation and temps, is it of the opinion that is still the one to try or should I go NECK, NEDK or even NECL (if available)? I'm focusing on fixing the just-barely-off-idle rich problem. (I'm attaching the Suzuki RM needle chart someone else so graciously posted in another post).

Thanks for any input.

[Enmerdeur]

I am running the NECK in my KTM 300 here in Utah with good result. The K indicates the straight portion of the needle, K being leaner than the J. That is the part of the needle that helps with the off idle parts.

I am going to try it in my Beta just to see how it goes. Since putting the higher compression head on my Beta it seems to want richer jetting. Probably start with the NECJ (since I have one already) and go from there.

Rocky Mountain usually has these needles. Just go the OEM parts section under 2008 Suzuki RM 250.

[DirtDogger300]

Emmerdeur,

I've been suspecting that a head with more compression needs richer jetting as well. While the jetting from the Beta chart works to some degree (except N2ZK too lean) for my 2014 300 RR RE I have found better results with the following.

My current Jetting/Setup is as follows:
Typical Riding Elevation: 4500-9000+ ft here in Cache Valley Utah.
Main Jet: 162 or 165 (I've been told that this could "easily" be a 168 but haven't tried it yet)
Needle: N8RH (I do want to try the NEC? series needle for comparison and possible sanity measure but don't expect an improvement as most riders seem to be much lower elevation whom are running this needle (NECJ anyways) and claiming improvements).
Needle Clip Position: 2nd from Top
Pilot Jet: 35
Air Screw: 1-1.5 turns out from fully in
Premix: Redline Synthetic mixed at 40:1 (Ester based)
Head: Has been modified from stock and is marked -0.030” (not sure all what was done to it exactly)
Pipe: FMF Factory Fatty
Powervalve Adjustment: Stock (1.5 turns in from out flush)

The next closest performing needles seem to be the N2ZW in the colder range and N2ZJ in warmer range but the N8RH is smoother overall and I feel more torque as well. It works good for me from about 70-95+ deg. F outside temps. Below 70 deg. F and it goes lean with delayed throttle response and low idle. The N8RH needle can be found on a 2012 KTM 300 from Rocky Mountain I believe.

Please report back results if you try the NECJ needle in your Beta.

[Enmerdeur]

Good info. Thanks.

[Kels]

We find the N8RH needle works excellent in the higher alts..

[Enmerdeur]

Looks like the N8RH is under the 2013 300.

[Philthy]

Both of you do the same riding/elevation as me here in Utah, so that's the info I was looking for. I'll plan on picking up a couple NEC? and the N8RH and plan on riding this Sunday and will report back with some results. Thanks!

[Coloradoenduro]

Philthy,

I got in 45 miles of riding on Saturday and the splooge is still an issue. I'm running the stock N2ZW. At 9,400' ASL, the bike runs a little ratty at light throttle during low to mid RPM's. It ramps up just fine with heavier throttle and decent RPM's. It runs smoother at the lower elevation of 7,000 ASL which is where I live. I don't want to get too carried away with leaning her out because it's pretty close at 7,000'.

The bike starts very easily hot or cold the way that it's set up now.

Besides lowering the float level, I'm going to install a different needle in mine tomorrow. The average elevation that I ride at is 9,000' ASL. According to the manual, I should be using the N2ZK at the top clip. Have you tried the N8RH?

Does anyone know if the N8RH is equivalent to the N2ZK, N2ZJ or neither? I wasn't planning on re-jetting because I only want to change a few things at a time.

Thanks

[Philthy]

I STILL haven't been able to get out and ride/test, but I did order some needles and have some ideas for you Coloradoenduro.

Your "the bike runs a little ratty at light throttle during low to mid RPM's" is exactly what I'm trying to cure. Running too lean down low creating spooge. It's only getting warmer here so leaning is the direction I'm going.

The last letter H, J, K etc. is the needle diameter that affects this range. I've yet to try the NECK (Suzuki) I ordered, but it is the leanest diameter I have. I won't be trying the K8RH (KTM) unless I get really high or it gets cold as it is too far in the rich range. I'm pretty sure I'm going with the Beta suggested N2ZK (or even try the N2ZL) and if too lean at higher rpm, use the Suzuki becasue....

I measured them. The KTM has dimensions really similar to the Beta, tapers down to 1.80mm (leaner at full throttle) than the Suzukis which taper to 1.45mm.

[Kels]

I would still recommend the N8RH needle... I have this bike and ride at the same or higher elevations.. It works very well

I would also add some air vents to the airbox.. This helps low rpm performance..

The 160 is TOO lean on the main..I would bump it to the 165..

Then when you really want it to run better.. change the head...

I have 2 of these bikes.. BOTH in a different stage of tune (different mods)

The engine is very smooth...with the above suggested changes..

Give it a shot.. You will not be disappointed