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NECK Needle for Summer - How's She Sound?

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It's great but perhaps it can be even better. I get distracted by the misfiring on initial throttle roll open. It's not a blubber. Just that popping before it starts to pull cleanly. They should be able to pull clean at all times for any throttle position and RPMs.

What do you think - Is that popping sound a function of throttle position or revs? It seems to be related to your throttle use because you're not changing bike speed or shifting gears.

Maybe it's not jetting. I see you have a small 42 pilot. I guess you have the stock #7 slide and your K needle is suppose to cure the 1/8th stutter.

Maybe it's a scavenging thing at low RPMs. The reeds or perhaps the type of pipe you're using.

Yesterday I installed my 250 top end. Same jetting I had on it 18 months ago. Hope it works great. I'm richer than you on the needle and pilot but I use the leaner #8 slide. I tried working with the #7 slide but gave up.  I also remember the 170 main jet made a lot less power than the 168.

My 250:  Slide=#8, PJ = 45, N=NEDJ-3, MJ=168,  pwr=40. Squish = 1.5mm. Pipe = Fatty.

Edited by numroe

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That popping is what I am chasing with jetting. Maybe you are right and it's not jetting related? I don't know. I switched back to 45 and NECJ needle today and the bike ran much stronger. Popping was the same. It's done it with two different carbs, two sets of reed boxes and reeds, two different CDIs (250X and 250). Maybe electrical? I did notice the black wire coating is pulled off about a 1/4" before wires go into the stator case. Will check those for chafing on Monday.

My 250:  Slide=#8 (notched by JD), PJ = 45, N=NECJ-3, MJ=170,  pwr=50. Squish = 1.016mm. 225 psi compression. Pipe = FMF Turbine Core II. Reeds = Stock/new.

 

EDIT: Rode in 93 degrees, humid, sea level today. Popping is at throttle position (just off idle). Sounds bad on video, but can't feel it riding and don't notice it much at all. Bike feels on the pipe all the time.

Edited by LSHD

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I'm confused. Although you cannot feel it, it would be nice to remove it. I expect you would feel it if you could remove it because the throttle response would be a little more predictable.

Since the popping sounds is a function of throttle position my first guess would be rich jetting near 1/8th open. But you have a #8 slide and also you found it runs stronger with the richer pilot and needle straight section. So going leaner doesn't make sense.

Electrical doesn't make sense to me, if it happens at a specific throttle position.

Assuming not jetting, I'm thinking case pressure/pumping (reeds), and then scavenging and then the burn.  When the cylinder was last removed did you inspect the PV function and also look for any defects in the transfer port windows?

What spark plug are you using?  Have you tried a different fuel and also premix oil?  Just to be sure.

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Yes, going richer leads to more blubber, but going leaner robs power.

Have tried different fuel, not premix. Have tried different plugs. Running BR8EIX plugs and have run stock.

Have NOT checked power valve. Will take a look on Monday. How could the power valve cause this?

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I would give unplugging your throttle position sensor a try, might be a long shot but it's simple to do and won't hurt a thing. I'm not familiar with virb, is that squiggly white line with the red dot some kind of elevation indicator so the vid is a downhill section?

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Already swapped TPS when I swapped carbs. Still easy to try. 

VIRB will show all kinds of things. The white line is a small overhead view of the trail I was on. 

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6 hours ago, LSHD said:

Have NOT checked power valve. Will take a look on Monday. How could the power valve cause this?

It's just a guess. Like halsy's good idea to disconnect the TPS (completely) and try that.

If the 3 valves are not operating correctly, then it would effect the burn. Long odds, but I'm running out of guesses. I do know that popping can go away.

Have you done any lowering or raising of the ports (cylinder) or still got the stock heights and base gasket?

You should try a stock muffler if you can. In case the Turbine Core 2 is causing a restriction and rich condition most noticeable at 1/8th throttle.

Another experiment is you could try the NExH needle which is richer on the straight section, combined with a smaller pilot like a 42 or 40. Just another stab in the dark. Depends how keen you are to play around.

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2 hours ago, LSHD said:

Already swapped TPS when I swapped carbs. Still easy to try. 

 

Don't swap, just unplug it.

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4 hours ago, numroe said:

It's just a guess. Like halsy's good idea to disconnect the TPS (completely) and try that.

If the 3 valves are not operating correctly, then it would effect the burn. Long odds, but I'm running out of guesses. I do know that popping can go away.

Have you done any lowering or raising of the ports (cylinder) or still got the stock heights and base gasket?

You should try a stock muffler if you can. In case the Turbine Core 2 is causing a restriction and rich condition most noticeable at 1/8th throttle.

Another experiment is you could try the NExH needle which is richer on the straight section, combined with a smaller pilot like a 42 or 40. Just another stab in the dark. Depends how keen you are to play around.

The NECH needle is what worked best in my 03, it really liked the extra fuel initially. 

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7 hours ago, Bricktop72 said:

The NECH needle is what worked best in my 03, it really liked the extra fuel initially. 

What pilot, slide # and needle clip did you use with NECH?

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Fixed! Stuck power valve was the problem. I pulled the motor to do a leak down (I know I could have done it on the bike, but I felt like I might need to replace seals and wanted to do this off the bike). This first step lead to finding a sticking main power valve due to the cylinder being overground by some lunkhead. Ended up replacing the cylinder, piston, rings, pin, full top end. While it was apart, did all the swingarm and linkage bearings, wheel bearings, new sprockets and chain. The works. 

Finally got it all back together and started it today. Purrrrrfection from the first kick. Well, I did have to back out the air screw. But what a difference. I knew immediately the sputtering problem was solved. Still might fine tune jetting a little, but it's excellent right now.

My 250:  Slide=#8, PJ = 45, N=NECJ-3, MJ=170,  pwr=50, Air Screw=2, Squish = 1.25mm/0.05", Pipe = stock

Should I swap out the power jet for a 40? Have one in the box. May also try a 168 MJ.

Edited by LSHD
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That's great to hear. Congrats.

15 hours ago, LSHD said:

Should I swap out the power jet for a 40?

I think the pwr jet is personal pref.  If you try the smaller 40 then don't try a smaller main jet at the same time.

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53 minutes ago, numroe said:

That's great to hear. Congrats.

I think the pwr jet is personal pref.  If you try the smaller 40 then don't try a smaller main jet at the same time.

Thank you my friend. And thanks again for sharing your knowledge and personally helping so many of us, including me. 

Really can't wait to get out on some single track and just enjoy the bike.

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Will do, Ron. Might rain tomorrow, but if it clears up enough, I'll ride it up and down my road so everyone can hear it. Rode Manchester (nothing but whoops) today, and it was really a treat. One kick start and instant idle. One kick restart even after dumping gas out of the carb on a get off. 13:50 is a bit low geared, but I'm going ride it several times to give it a good evaluation. Will probably go to 14:50 (I was running 14:48 because that was on it when I bought it).

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Okay. First start of the day. Easy start. Good idle. Excellent performance. Still might try a 168 main jet and possibly go to NEDJ-2. Video is a good example of why I don't use forged pistons. Didn't exactly let it warm up!

 

 

 

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