New YZ250 air screw 5 turns out?

[BMB-SALES]

Just bought new 16 and took it out stock first week, and it kept dying. When I got home I setup the air screw, and it ended up highest idle was about 2 turns out, which made me think pilot is correct, but low idle with good response is 4 1/4 out.

I thought this was weird, but my buddy just got a 17, and IT also came over 5 turns out, brand new, stalling after a few seconds, probably only needing slight dial in of screw. 

Is this normal?  I always thought the screw needed to END UP about a turn and half out to be correct...or is that just for highest idle, and mine is normal?

BMB

[DEMI]

wouldn't 5 turns out be almost out of the carb?

[BMB-SALES]

58 minutes ago, DEMI said:

wouldn't 5 turns out be almost out of the carb?

Pretty damn close. 

[thebob_za]

Pilot jet is too big. Buy a couple smaller sizes and experiment. Jetting chart in the manual should be a good place to start

[BMB-SALES]

Two brand new bikes from diff dealers at sea level ?  That would tell me that every new bike either needs a pilot or won't run, no???? 

[mlatour]

Float level is set too high, making the engine run rich, needs more air to compensate.

 

Are you running 32:1 ?

Say you're premixing at 50:1 with the stock jetting, less oil = more fuel/richer, again needing more air to compensate.

Edited February 6, 2017 by mlatour

[BMB-SALES]

21 minutes ago, mlatour said:

Float level is set too high, making the engine run rich, needs more air to compensate.

 

Are you running 32:1 ?

Say you're premixing at 50:1 with the stock jetting, less oil = more fuel/richer, again needing more air to compensate.

I'm running H1R at 40:1, which I've always had luck with, so I know I'm a little rich due to that, but don't forget that both of these came from two diff huge east coast dealers, two diff years, and both more than 5 turns out?  Floats set too high on two new factory bikes?

does anyone know if these are set at factory and shipped, or adj at the dealer after "assembly"? 

I was starting to think that the 1 1/2 turns out, like has been listed in motox action for years, was just the point of highest rpm, then adjust from there due to temp,humidity, altitude etc, but I go from max rpm at 2 turns, to 4 1/4 for nice barely idle but snappy response, where every now and again it will stall...

[HevyRotashunz]

I'm running H1R at 40:1, which I've always had luck with, so I know I'm a little rich due to that, but don't forget that both of these came from two diff huge east coast dealers, two diff years, and both more than 5 turns out?  Floats set too high on two new factory bikes?
does anyone know if these are set at factory and shipped, or adj at the dealer after "assembly"? 
I was starting to think that the 1 1/2 turns out, like has been listed in motox action for years, was just the point of highest rpm, then adjust from there due to temp,humidity, altitude etc, but I go from max rpm at 2 turns, to 4 1/4 for nice barely idle but snappy response, where every now and again it will stall...

Any more than 3 turns out means you need a smaller pilot jet, period. And yeah, set your float height first.

[mlatour]

Yes, too high a float is possible even on a brand new bike,

right off the showroom floor my YZ125 ran rich at low rpms and leaked fuel out of the overflow tubes when leaned over ever so slightly.

Re-setting the float / fuel level about 1mm lower than the stock settings fixed all these issues.

Don't trust a dealership to properly set up a bike's carb settings, they get it running best they can but that doesn't mean

they're achieving it the proper way, the air screw can only compensate so much for a too rich pilot jet.

 

Not sure how familiar you are with late model YZ250 but it's a known issue that the cylinder compression squish height

(the gap between the top of the piston's outer edge and the cylinder head) is way off from the factory due to machining tolerances,

making the engine difficult to jet and run cleanly at low rpms.

Getting that corrected makes for better throttle response and, lessens the tendency of detonation. (avoids having to run race fuel)

Plenty of discussions about this in the Yamaha 2-stroke specific sub-forum.

Edited February 7, 2017 by mlatour

[Motox367]

Everyone ive had and tuned are normally around 2 turns out. Any brand . Awesome bikes tho ??

[BMB-SALES]

4 hours ago, Motox367 said:

Everyone ive had and tuned are normally around 2 turns out. Any brand . Awesome bikes tho ??

Yeah, before I set the float, I put a #48 pilot in and now it's down to 3 1/8 turns out. I'll check the float level and try a #45.  

I guess it kind of makes sense running 40:1 and I went up one on main jet to #180 with the pipe, and probably didn't even need to do that but wanted be safe with short silencer. 

[HevyRotashunz]

Yeah, before I set the float, I put a #48 pilot in and now it's down to 3 1/8 turns out. I'll check the float level and try a #45.  
I guess it kind of makes sense running 40:1 and I went up one on main jet to #180 with the pipe, and probably didn't even need to do that but wanted be safe with short silencer. 

I run a 45, 1 3/4 out at 40:1. You're getting close.

[BMB-SALES]

15 hours ago, HeavyRotation said:

I run a 45, 1 3/4 out at 40:1. You're getting close.

Did you have to adjust your clip at all after two jumps on pilot?

[NEGbrap]

On 2/5/2017 at 10:41 PM, BMB-SALES said:

Just bought new 16 and took it out stock first week, and it kept dying. When I got home I setup the air screw, and it ended up highest idle was about 2 turns out, which made me think pilot is correct, but low idle with good response is 4 1/4 out.

I thought this was weird, but my buddy just got a 17, and IT also came over 5 turns out, brand new, stalling after a few seconds, probably only needing slight dial in of screw. 

Is this normal?  I always thought the screw needed to END UP about a turn and half out to be correct...or is that just for highest idle, and mine is normal?

BMB

That's so crazy out of wack. Id check all the culprits. Carb, Filter, Plug. Pull the float bowl off, check all the jets. Spray the jets with some carb cleaner, and blow through with an air gun (hold them tight or they might go for a walk) Then check the needle. Make sure all your jets are fresh and clean, and factory and that the needle is also factory. Check air filter. Check plug. Heck just put a fresh plug in.

Fresh gas. Oil at 32:1 or 40:1 per factory specs and oil recommendations. Ive run HP2 and Yamalube 2R at 32:1 and its been great. Some like Castor 927, or the Maxima Super M.

Reset all carb adjustments to factory. Jets, Needle, Clip. If it still runs like crap, slap in the following.

45 Pilot

NECG needle middle clip

175-180 main

Air screw at 1.5 turns out. When you turn it in to seat, you should feel resistance, but not like cranking on a rear axle bolt. Like a stiff doorknob. Thats seated. Then back it out.

Kick it over, ride it around to warm it up. Then use your butt dyno to determine the problems. Adjust from Air/Screw, Pilot, Needle clip, Main. In that order. 

If it runs hot and you get a BOWWWWWWWW sound when you wack it, its lean. Jetting on a stand is not jetting under load. Dont trust it. RIDE IT. If you get a gurgle, studder, and then a clean out that's rich. If its hard to kick over and gurgles and studders all the time its super rich.

If you don't have access to a NECJ the stock should work, but be a little dramatic in its fuel delivery.

 

Honestly I love the JD kits, with a couple extra main and pilot jets they work every time in every bike I have used them. 2 needles for all the temps you want to ride, and OEM jets that cover most of your problems. PM me if you need more help, or you are having trouble with the bike.

[HevyRotashunz]

Did you have to adjust your clip at all after two jumps on pilot?

I'm on 3rd clip, blue JD needle. At 600-3k, above 3k I swap to 3rd clip red JD needle. My bike is completely modded so take that with a grain of salt.