jimfergie

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About jimfergie

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  1. so Sudco replied and said they can't help me, I have to go back to the OEM dealer (like they know) So the question is: what is the stock Yamaha NFPR needle's dimensions compared to a Keihin? I've chenked a couple websites and the alternative Yamaha needles are "backordered"
  2. thanks for the reply, I like what you were saying about how critical those two are. I want to experiment with just the diameter changing, not the taper or length. I just got back from the Yamaha dealer and I guess it really doesn't surprise me that they don't show the alternative needles being available at all! I will call Sudco and see if they can cross reference what the stock Yamaha and Honda needles are compared to Keihin's.
  3. still working on my 06 YZ450 popping. last evening I think I pretty much eliminated the popping on decel with a 50 pilot, 3 turns out (85 degrees, sea level) but there was still a bit of surging/ hesitation at exactly 1/4 steady throttle. (stock needle, 5th clip). To experiment I went to the 2nd clip, it seemed a bit smoother, but mild crackling (leaner, right?) So I can figure out the Keihin OC-xxx measurements, but what about Yamaha's stock NFPR and Honda's NCYQ needles? how does one convert these to Keihin's needles for comparison? I wanted to try a couple of straight dia. changes without changing the length or taper. Obviously I can use the stock Yamaha's but wanted to see where they are compared to the others.
  4. JD Jetting responded, it's Keihin's Idle Mixture Screw (fuel screw) Thank You JD!
  5. GrayRacer when I look at the parts diagram for the WR I see the whole AIS tubing and such, but on the side of the carb is the Air Cut Off Valve, diaphragm cover, etc. So these are connected? if so, how? And for all this discussion the main reason the person new to YZ's like me is the fact that the KTM and CRF didn't do it! I'm just super curious and want to see if I can correct it, if in the end I can't, then I can make the decision then to live with it or sell it.
  6. good info, I'll go back over that info on the Air Cut Off valve tonight, thanks. I returned the old carb to the dealer today, I didn't want him to be out, but Yamaha gave them the OK to replace it, the new one seemed to be able to have it's fuel screw be more effective at idle. I blew some money on the Power Now, I won't put it in though until I mess with jetting some more. I think my next step is to try the extremes of pilot jets and fuel screws (40 vs 50 or whatever) as well as the extremes of clip settings to see if I can come up with a solution. The shim I used, by the way, came out of my Hot Cams kit and it was about 1/2 a step less than the shim that came out of the bike.
  7. Matt, is the spec on the slide you're talking about the air space left open when the slide is at an idle position? I noticed the part number for the 06' slide is different from past years. Being that it's only $250 it unlikely I'll buy one to try it. I've been thinking of playing with clip position vs. idle screw setting....
  8. The Air Cut Off is on the left side of the FCR, it's on the WR apparently not on the YZ and the CRF's Keihin doesn't even have the molding on the side to have it. Why not? For those who don't mind the popping, obviously it depends on how much and how loud is acceptable to your ears. Sometimes it's mild and OK, the next day it's more quantity and louder. That brings me back to original question, what is it about the YZ that causes it? the 3 intake valves, the velocity of air through the carb, the different slide, the different Keihin ? On the intake valve, it was just one, the left one and it was right on the edge so I went to the next shim down so it was more in the middle of the spec.
  9. I checked the valves, one intake was just a bit tight so I reshimmed it, as I said I sealed both the exhaust joints with high temp silicone. I'll look into the slide, interesting. No, I've screwed around with the fuels screw from nothing to 3 turns out, really very little effect on popping or idle speed. I can hear what is considered "a little popping" on decel, but this is quite a bit more than that. Again the CRF and my 04' KTM 450SX were never touched, didn't matter as to altitude or temp, over three years. Maybe they were rich, I don't know, they were as they came from the factory, they started and ran with no fuss. I also see that the WR uses the Air Cut Off feature on the Keihin specifically to eliminate the popping on decel, why on the Yamaha?
  10. In the Keihin website along with the pilot jet/ fuel screw they have listed I.M.S. as influencing off idle performance, any idea what I.M.S. is?
  11. I just had the dealer and Yamaha let me take a carb of another new bike to put in mine, (the usual popping on decel) Rode it yesterday at the track, the bike actually runs great, fairly minimal pooping on the last bit of rpm's. I had another guy with an 06 and an expert rider ride it and he thought it was fine, the little bit of popping is OK. So this morning I put in a 168 MJ (we have a 48 PJ, stock needle 5th clip, 3 turns out FS and had a 165 MJ yesterday) and it pops pretty bad after riding it for 5 minutes. So obviously it's 15 degrees cooler this morning, maybe 60-65 and yesterday it was maybe 75-80. I sealed the exhaust, checked the hot start for slack, rejetted, reneedled several times, NEW carb, so the question is what is it about the YZ that requires this, the 06 CRF I had didn't do this at all, never touched it, no popping ever. The carbs are different on these two bikes, both FCR's but different. At the lowest RPM's on decel it seems the motor simply can't pull in the fuel it needs, or the air it needs to pull the fuel. Any thoughts?
  12. you can read my story on jetting my new 06 YZF on the jetting forum, I love the way this bike handles and the suspension, great power, but screwing around with the carb has been a nightmare... I'm almost ready to give it back... Jim
  13. I have the stock needle and set as described above. We went to the track last night, 70 degrees and it actually started and ran fine, minimal if any popping, but again after riding for 15 minutes, tried screwing in the fuel screw and you can bottom it out and the engine keeps running fine (48 pilot jet) and as I mentioned, I'm worried about the white plug and any lean engine damage. The dealer told me yesterday that Yamaha would swap out a new carb and see if that works better. They're so busy though that I may have to go down and swap them myself.I will pull the plug and take that with me.
  14. another thing, it does seem like that bike runs hot, the pipe gets red FAST and I can burn my hands on the transmission covers 10 minutes later while I'm busy making jetting changes. Jim
  15. I'm in the same boat. I described my problems last week, an update: After many rejettings and carb cleanings, the bike still isn't right. Some popping on decel and it seems like it's missing or surging at low, steady throttle setting. I took it back to the dealer and the expert there looked at it and rejetted to 168 MJ, 48PJ, stock needle 5th clip, 1 turn out on FS. It didn't pop in the parking lot (70 degrees) but did back home (90 degrees). Rode it the next day, it started and ran OK, still a little pop but better. The thing that worries me is that when I checked the valves (just one intake a pinch tight) the spark plug was WHITE (I've never taken a plug out of anything that wasn't brown or black). The other weird thing is like yours, I can turn the FS in all the way and the motor keeps running fine, even with the stock 42 in! I can pretty much eliminate popping by turning the idle all the way down, so much that if you turn the throttle it may die. I can simulate the popping by pulling the hot start while decelerating. The dealer is looking into Yamaha replacing the carb. Never had a problem with my 04 KTM 450 or my 06 CRF450. Jim