Just got my new 07!

[DesertRacer2]

I just picked up my 07 on Friday. I installed the 170 main jet and 48 pilot jet. That has completly eliminated the popping on decel. Thanks for all your help guys! I can't wait to take it out next weekend!

[barch88]

Congrats man

Did you do this stuff yet?:

http://www.transworldmotocross.com/mx/how_to/article/0,13190,1012822,00.html

http://www.transworldmotocross.com/mx/how_to/article/0,13190,663693,00.html

http://www.transworldmotocross.com/mx/how_to/article/0,13190,700369,00.html

[DesertRacer2]

Sure did! How do you like your 06 so far? I know its basically the same bike.

[sharky_do_do]

I just picked up my 07 on Friday. I installed the 170 main jet and 48 pilot jet. That has completly eliminated the popping on decel. Thanks for all your help guys! I can't wait to take it out next weekend!

Desert racer - Thanks for posting this, I think I might need to do the same. I don't have the hardcore popping on decel, but I have a horrible bog on my 07 right when I wack the throttle wide open. Did you have this too?

[DesertRacer2]

No, I haven't noticed that on my bike, but then again, I haven't whacked it all the way yet. When I roll it on quickley, it doens't bog. I am taking it out this weekend, I will let you know how it goes.

[kyle450rider]

No, I haven't noticed that on my bike, but then again, I haven't whacked it all the way yet. When I roll it on quickley, it doens't bog. I am taking it out this weekend, I will let you know how it goes.

Mine doesnt have the bog except when the throttle is quickly opened.I have no jpopping on decel.I wouldnt worry about the bog because i usually ride a fourstroke with the roll on roll off on the throttle but...its gonna be a problem in a situation when i need to whack it open to clear something.

[YZ250F_Rider]

make sure the idle is up where it belongs. there is a lot of inertia and it takes a bit to get it spinning. the idle almost sounds like it's too high of an rpm when it's where it's supposed to be.

If that doesnt eliminate it, then look into doing the AP mod the 06's have done.

[grayracer513]

Be certain not to judge the throttle response by what it does in neutral. The timing gets shifted by the CDI when the bike's in neutral, and it will act quite differently than when in gear. Believe it or not, your ability to win sonic races while on the stand is not something that Yamaha considers to be the least bit important.

[gmtech16450yz (motobark)]

Hey Gray, there might be something to the '07 stumble or hesitation complaints. My buddy just got an '07 and he rode it for the first time last Sunday. The first thing we both noticed when we switched bikes (mine's an '06) was that the '07 had a lean hesitation on quick throttle, like in a berm or jumping a water break. My '06 definitely didn't have any hesitation in the same situations. Other thing we both noticed that was a little weird is the '06 motor seemed like it vibrated noticeably less, may just be a break-in thing, mine has 1k miles and his is brand new.

I only got 5 or 10 minutes on the bike but it seemed like it needed more pump to me. That may be why some guys are having success with wiring the accel pump spring. I'm not sure I like that approach, I think there's better ways to fix a weak pump spray than defeating the purpose of the spring. (That's another subject though.)

He also said it had a lean surge on steady light throttle cruising, like doing 25mph on the main road between trails. If we wanted to fiddle with it instead of riding, I would have tried swapping our needles to see what that did to both our bikes, since I was thinking about trying the '07 needle anyway. That needle might be a tad too lean for the '07 though, like I said, we didn't want to waste time working on it, too busy riding! We did switch the pilot from the stock 45 to a 48, he said the surge or the hesitation didn't get any better or worse. The fuel screw was at 2.75 with the 45, I think he was at 1.75 with the 48. (We did the pilot change more to get the fuel screw in a little.)

On a side note to keep in mind when the question comes up, between my TiQ (same as Q2) and his stock muffler with the PMB end cap and quiet turn-down, there's a big noise level difference. The TiQ is way quieter than his setup, but still barely passes at 97.4db. I'm not sure his will pass, we didn't have it tested or got pulled over. I've seen the sound level question come up so I figured I put that in your knowledge banks!

When we get the hesitation figured out I'll let you know what we did to fix it. Evidently there's more differences in the '06 to '07 carbs than just jetting, my buddy said there were some casting changes too?

One more thing, (sorry, I'm rambling:bonk: ) he came off a KTM 520, he's a very good A level rider. The first day on the '07 YZ450 and he's riding better than I've seen him ride in the 20+ years I've known him! Like you've said many times here, the bike is so good it makes just about anyone faster.

Sorry for the long post.

[grayracer513]

Yeah, I don't think that the fact that the pilot jet is a 45 instead of a 42 means that they are any richer to begin with than the '06 was, and it was clearly too lean on the bottom unless you were at altitude.

On the lean surge, I would start with the pilot. The key word to me is "light throttle".

As delivered, my '06 didn't really run that well, jetting-wise. Now it works fine, but I'm expecting to have to fatten it a little for the desert now that the temps are down some. Our favorite desert areas are major low altitude stuff, below sea level in some spots, and the jetting was set up to run in the summer at 2800-3600'.

[barch88]

Sure did! How do you like your 06 so far? I know its basically the same bike.

I like the '06 a lot. I haven't seen it for months now though, its been sitting in the garage, and I'm sitting in the house laid up hurt for months, and month(s) to come? Awesome bike though, love it. Not one problem, and you can see the mods I done to it, in my garage.