Beta Xtrainer JD Jett burping/1/4 throttle issue

[Beta_Man90]

Hi everyone. I have been very active on thumper talk after I purchased a 2015 xt that has a JD Jett kit. Well after reading high and low and emailing JD I still have not arrived at a setting that will prevent the burping at 1/4 throttle. I currently reside at sea level and it's 60-75 degrees. What are settings people have found to work on here? Here is an email from JD. Any other help or interpretations of this email would be greatly appreciated!

The jet kit jetting runs crisper and cleaner, just as you described, and with this comes a slightly hotter running motor. The hotter and cleaner running a 2-stroke motor is, then it also becomes more sensitive to detonation and lurching/knocking symptoms as you let off the throttle. The best way to solve an issue of detonation is to use a higher octane fuel, or else live with overly rich jetting. If you are using pump fuel with ethanol, then make sure you use premium and see if you can find ethanol-free premium fuel to run.
See-
http://pure-gas.org/
Also, try using a slightly richer air screw setting by turning inwards to 1 to 1 1/4 out from closed. Keep the idle speed set very slow to have a more consistent idle and low speed jetting too.
You may want to try using the Blue marked needle as an alternative to have a slightly richer off-idle jetting. It may need 1 clip position richer at the same time to even out the overall jetting.

Thanks,
James

Hi James,

My name is Joseph and I have always heard great things about the JD Jet kits for all dirt bikes across the board!

Anyway I just picked up a 2015 Beta Xtrainer 300 that came with your jetting kit. I have followed the settings for the stock carburetor, elevation 0-1000ft, temp above 45 degrees (Red needle, #4 position, 38 Pilot jet and 152 main jet, Air screw 1.5-2 turns out from all the way in depending on temp). What has been going on and others can speak of this too on numerous forums is that at around ¼ throttle or even letting off to coast the bike starts burping/or acts jumpy until back on the throttle. I have gone ahead and tested to see if the same issue occurred with the stock needle, etc and it didn’t happen.

I really want to use the JD kit because it runs much crisper and cleaner but this has been very noticeable since I put it in and it’s just getting irritating. If there is any other advice or setting suggestions you could offer that would be fantastic. Thank you.

Best,

Joseph

[Hammer]

NECJ needle and a 35 pilot.

[Beta_Man90]

NECJ needle and a 35 pilot.

Which color needle is "NECJ" or do I need to purchase this? Is the the one being discussed that is Suzuki related? Also which clip position should I be on? Thanks.

[Clearvu1]

The NECJ is a Suzuki needle. You will likely have to get it from a Suzy dealer or you can get it online from one of the retailer that sells OEM parts. I think Motosport and Rocky Mountain ATVMC both have them.
I have it in my 250RR and it works very well. I'm at about 600' asl so it should work for you too. 3rd position (middle) seems to work great. I use the 35 pilot.

[Beta_Man90]

The NECJ is a Suzuki needle. You will likely have to get it from a Suzy dealer or you can get it online from one of the retailer that sells OEM parts. I think Motosport and Rocky Mountain ATVMC both have them.
I have it in my 250RR and it works very well. I'm at about 600' asl so it should work for you too. 3rd position (middle) seems to work great. I use the 35 pilot.

Alright so this is what I was reading up on through some other threads. I really appreciate all your responses (I'm really a novice when it comes to jetting but I'm really getting a grasp on it now.) One more questions how far out or how many turns do you have your air screw from all the way in? Whats your operating temperature range currently? Thanks!

[Clearvu1]

About 2 turns out from all the way in, but you'll need to set yours. Start the bike, let it come up to temp, turn the air screw all the way in until it seats lightly. You should notice the idle slowing and getting rough. Turn the screw out until the idle smooth's and increases in speed. Continue turning it out until the idle begins to slow and turn rough again. Stop, turn the screw back in a 1/4 turn or so and call it good. If you can't get these results in 3 turns or less you'll need to replace the pilot jet.

[Beta_Man90]

About 2 turns out from all the way in, but you'll need to set yours. Start the bike, let it come up to temp, turn the air screw all the way in until it seats lightly. You should notice the idle slowing and getting rough. Turn the screw out until the idle smooth's and increases in speed. Continue turning it out until the idle begins to slow and turn rough again. Stop, turn the screw back in a 1/4 turn or so and call it good. If you can't get these results in 3 turns or less you'll need to replace the pilot jet.

I appreciate this. I'm going to be ordering the needle shortly unless I can find it locally.

[Beta_Man90]

About 2 turns out from all the way in, but you'll need to set yours. Start the bike, let it come up to temp, turn the air screw all the way in until it seats lightly. You should notice the idle slowing and getting rough. Turn the screw out until the idle smooth's and increases in speed. Continue turning it out until the idle begins to slow and turn rough again. Stop, turn the screw back in a 1/4 turn or so and call it good. If you can't get these results in 3 turns or less you'll need to replace the pilot jet.

Hi finally got the NECJ but I think with the cooler weather here in Maine it is running a little too lean so I have had suggestions to go back to the 38 since the bike only runs well with the air screw all the way in on the 35pj.

What exact settings do you have on your carb right now?

MJ #
PJ #
Clip position
# of Air Screw turns out from all the way in.
Also how many turns out from all the way in is your idle screw (the one with the spring around it.)
Elevation you said was 600ft?
What has been the temp there on average?

Thanks again!

[Clearvu1]

Main and Pilot haven't been changed, NECJ needle in middle (3rd) clip. Strange, I have to turn my air screw out at least 2 turns to get clean idle condition. I don't think I could get a 38 pilot to work at all. Idle screw is turned in quite a bit but I've never counted the turns. Temps are moving up. Bike ran perfectly when temps were 70's - 80's. Over 90 today, planning on riding tonight, we'll see how it goes.

[Beta_Man90]

Main and Pilot haven't been changed, NECJ needle in middle (3rd) clip. Strange, I have to turn my air screw out at least 2 turns to get clean idle condition. I don't think I could get a 38 pilot to work at all. Idle screw is turned in quite a bit but I've never counted the turns. Temps are moving up. Bike ran perfectly when temps were 70's - 80's. Over 90 today, planning on riding tonight, we'll see how it goes.

So you're on a 152MJ and 35PJ right now? I'm wondering if it has anything to do with being a different bike? Once I put the 35pj in, it seemed to be running way too lean.