06 YZ 450 jetting

Thanks to you all, installed a 48 pilot and 170 main from day one. Left the needle/clip position and leak jet stock. Huge improvements. I am in the San Jose, Ca with a temperate climate. Seems to me someone mentioned some testing with the NFLR in the 4th position. Can't locate that data and can't get a feel for what direction, if any to go on the needle or clip. Has anyone tried different leak jets? Or am I there? Pump gas/stock exhaust. Thanks Bob.

Appreciate it Grey Racer.

thanks for the tip...Did you experience the bog off acceceration when you first picked your bike? I've noticed this.

Yes, with the 42 pilot, my '06 was too lean, and required too much care in rolling the throttle open to prevent it from stumbling. The 45 improved that quite a bit. I might end up putting a 48 in it for the winter in the desert. We'll see.

As far as the stumble goes, there are two things to bear in mind:

First is not to judge the performance by how it acts in neutral. There is a shift in the ignition timing and the advance map in neutral that will affect this. The bike was made to be ridden in gear, so what it does on the stand is meaningless.

Second is that when you are actually riding, there will hardly, if ever, be a time where you will be required to bust the throttle from closed at idle to WOT. It just doesn't come up. If you take a little time to learn to roll the throttle, opening it slowly at the very first, and faster as the engine responds, you'll be way ahead. After a very short time, it will become completely second nature, and the engine will respond virtually instantly.

Trying to get a four-stroke single to respond to an instantly full opened throttle from very low speeds by giving them massive doses of accelerator pump and ridiculously oversized pilot jets just dirties them up to the point where you've traded an imagined problem for a real one most of the time.

My opinion, of course.

RickK,

My 06' with the 42 performed as Grayracer mentioned. Tough to ride, backfire of course, and underpowered/temps in the 70s at sea level. It would idle surge in first gear and the head pipe would glow coming off the track. I realize they can glow at idle. Mine seemed so far off, I went straight to the 48. The bike pulls better on top with the 170 and seems to rev well. The 170 maybe a bit fat, but temps will be coming down soon. Thanks.

Tested the NFLR/4th position, 48/170 on pump gas...San Jose area and down at Zaca Station near San Louis Obispo. Sea level temps 60-75F. Works very nicely. The NFLR seems to be cleaner and more responsive. Not a huge gain over the stocker, but worth the 10 minute install and $12 or so. Sincere thanks to all for the timesaving help. The Zaca Station track is a national style outdoor track with fun obstacles. Big tables and large, no gap-uphill step ups, along with huge downhill, safe, ski jumps. It is about 30 minutes south of San Louis Obispo, Ca. Worth checking out if in the area. zacastationmx.com

Haven't got the '07 NFLR needle yet but I did try lowering the stock needle last time I rode my '06. Should be about twice the effect (leaner) of switching from the '06 to '07 needles.

Very lean off idle at the truck, but like Gray says, you don't ride the bike in neutral, you ride it with a load on it. Significant improvement in off idle response and rpm pick-up, a tad on the lean side of perfect. I tend to jet my bikes lean in the middle because it makes them rev out quicker and there's little chance of doing damage from being too lean. (within reason of course.) I was at about 1k elevation and it was a cold, dry day so it was about as lean as it's going to get. If you're at any amount of altitude or the temps are higher, you '06 riders might want to just try lowering the needle 1 clip.

The only place I think it would be a problem is if you had to have it sound tested, 4k rpm with no load is pretty lean and ends up testing louder. Even stock jetting is pretty rough at sound testing rpms so it's no surprise. Again, like Gray says, I wouldn't jet to pass a sound test because you'd kill the off-idle response when you're actually riding the bike.

RickK,

My 06' with the 42 performed as Grayracer mentioned. Tough to ride, backfire of course, and underpowered/temps in the 70s at sea level. It would idle surge in first gear and the head pipe would glow coming off the track. I realize they can glow at idle. Mine seemed so far off, I went straight to the 48. The bike pulls better on top with the 170 and seems to rev well. The 170 maybe a bit fat, but temps will be coming down soon. Thanks.

I put in a 45 and a 170 and the bikes runs fine now. Still some minor popping, but hardly even noticeable, then again, I haven't played with the fuel screw yet.

:worthy:

I sent you a private message on the track, thanks!

RickK,

Sent you a PM on Zaca Station MX.

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