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Yamahondaha

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About Yamahondaha

  • Rank
    TT Bronze Member

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  • Gender
    Male
  • Location
    California
  • Interests
    Building and riding Recumbent bicycles, Playing Drums
  1. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I do admit to being a trail rider but I don't ride in too high a gear, I tend to spend about 50% of the ride on the pipe. I have done a compression test and a leak test and both were good, besides if it were an air leak I would be too lean and trying to go richer. I did check what I know would make the bike run richer like the air filter is a new and clean UNI lightly oiled, my choke is working as I swapped the choke buttons between carbs with no effect on either bike, the carb is clean with no clogged circuits and I replaced the float and set the height to 15mm plus I have checked the RC valve adjustment and servo operation so I have to wonder why the factory jetting is so damn rich? Did I miss something?
  2. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I don't have any jets beside the 370, 380 and a 420 and since I will need to buy something I may as well buy the S-8 nozzle. All my experience with jetting a four stroke has been to fine tune with the clip position and move up or down on the jet size when you reach the end notch. The S-9 that came in the bike was not very sensitive but the S-7 seems to be way too sensitive. I feel that an S-8 should be right where it needs to be, the clip position will have less impact than the jet size increment. A new nozzle will cost me $14 where as a main jet only costs $6 I might not get the size right the first time and so $12 or more by the time I get it right.
  3. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I see the rings around the base of the insulators, at first I was looking lower at the ring on the left plug that must have been from cutting it (I was looking for a difference in the two thinking one was rich and one was lean). Now that I know where to look I will feel better about cutting my plug and reading the mixture ring. I still feel the S-8 will be less sensitive to clip position than an S-7 for my 250 but I am very grateful for all your input, couldn't have gotten to this point without it...
  4. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I don't think I'm doing a proper plug chop either as I have not cut one to see the mixture ring yet as there is no point in that till I get the bike running like it should.OK, I see now that the needle and nozzle do play a roll in WOT. I know this because I hit the nozzle with the needle on the way in with the throttle slide after a clip position change so it does create the opening between the two parts at WOT. I took your advice and raised the needle all the way up with the S-7 nozzle and stock needle with the stock 380 MJ and was way too rich again so I backed the clip up one position and was still too rich but one more clip position was too lean again so I swapped out the 380 MJ for a 370 and I am so close I can taste it, It feels good from beginning to full open but I still feel the S-8 is what I needed. The clip position is having more of an impact than the main jet swap. In three clip positions I went from too lean to too rich where as the main jet had so little effect, it should be the other way around IMO but the good news is I am almost done and quite ride-able. From here I will put an S-8 in it and size the MJ with the stock needle then dial in the clip position till it feels great, then I will do a proper plug chop test after I read up on how that is best accomplished, thanks for all your help....
  5. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I would also agree that the nozzle was only part of the equation and that a smaller nozzle with a smaller needle could let the same amount of fuel past but wouldn't the smaller nozzle also let less fuel by at WOT than an S-8 when they both have the same main jet? I put everything back to stock except for the 30 PJ and the S-7 nozzle. The idle was not responding to the air screw with the 32.5 PJ in it. I was able to turn it out past 4 turns with no change in the idle and so that is why I reduced it so I'm pretty confident that the 30 PJ is good as it was increasing the idle as I turned it out past 1 1/2 turns and dropped as I turned it in beyond 1 turn.My gut tells me that the S-8 with a 380 MJ would be similar to the S-7 with a 400+ MJ when the needle is in play but at WOT I'm not so sure. Based on how the bike ran with the float height dropped (Better throughout the entire throttle range but just a tad too rich) I was hoping to be closer to the goal with just the nozzle swap, I didn't want to be this lean and have to jet richer as I could have jetted the S-9 leaner and been OK. If all things are kept the same and just the nozzle was swapped out an S-8 would have hit closer to the mark for me than the S-7 and clip position should get me to the goal possibly without jet changes.
  6. Yamahondaha

    Help 2002 CR250 Carb Trouble

    OK, so based on what I understand the mixture ring is at the base of the insulator on the inside of the threaded part of the plug. I noticed that the two plugs pictured from "mynewcr250" had the dark ring on the plug labeled L (lean?) and the one on the right with no color was labeled R (rich?) so does that mean you would run with the MJ set on the rich side of things then bring it leaner with a smaller MJ until the plug chop at full throttle turns dark on the mixture ring then go back to the leanest setting that did not cause a dark ring? Or do you want it to have the ring? I'm guessing it is like the air screw tunning that once you determine the best setting with the highest idle response you should turn the screw back in 1/4 turn...
  7. Yamahondaha

    Help 2002 CR250 Carb Trouble

    Some more explanation please, where on the plug is this ring?
  8. Yamahondaha

    Help 2002 CR250 Carb Trouble

    I set the float back to 15mm, the plug was dark gray but the power was not there from bottom to top like it was when it was rich and I lowered the float. Needle was left on the second notch from the top, I know that is a lean setting but I was under the assumption that when you are at full turn of the throttle the needle is no longer in play. I guess I could check that when I dig into it next time but my impression is that an S-8 would be better for when winter hits and I'm looking to go richer again. The S-8 should work for both winter and summer but the S-7 will only be usable in the summer (IMO) No biggy, I will order one up and still have less than $50 into the TMX.I will re-load the video tonight and possibly include a pic of the plug after I swap the 380 MJ for the 420 from my 125...
  9. Yamahondaha

    Help 2002 CR250 Carb Trouble

    OK, got the S-7 nozzle installed today along with a 30 pilot jet, stock needle and main (380) jet but now it is a tad too lean all around. The plug is gray and it is not revving out on top and it is weak on the bottom too, it comes on the pipe but not as much as it has in the past. Looks like I should have gone with my gut and bought the S-8. I wonder if those who recommended the S-7 or less are riding at altitude? I am riding at sea level but at temps over 100 deg. I will order an S-8 and call it good, I feel good about how it will run with an S-8 based on how it did with the S-9 and S-7. The story of Goldilocks and the three bears comes to mind "This one is too rich, this one is too lean but this one is just right" http://youtu.be/s-EBa4XyJRE
  10. Yamahondaha

    Help 2002 CR250 Carb Trouble

    Yeah it is still dripping rich but I still have the S-9 in it. I just threw the needle from my 125 in it first clip position just to be able to ride the thing, my S-7 nozzle won't be here for another two weeks and I plan to dial it in then along with the 125.
  11. Yamahondaha

    Help 2002 CR250 Carb Trouble

    Today I was able to ride the bike on the pipe for the first time since I got it about a month ago. I swapped out the needle with the fatter tapered 125 needle and installed a 30 PJ. My idle went way up after the PJ was installed but I'm still on the dark side of brown for plug color, I was way too rich with stock jetting. The S-7 nozzle won't ship for another two weeks but at least I can ride the bike while I'm waiting. It should just get better and better from here, I'm stoked! Here is a video of the ride today, you can hear the bike run pretty good but you will also see that I don't have the riding skills necessary to pilot such a beast "I am not worthy"http://youtu.be/vcz4tFOAq7o
  12. Yamahondaha

    2003 cr250

    The clutch probably has notches worn into the basket, that would explain the symptom you describe. Does the exhaust smoke? If so check crank seals, carb jetting, float valve. air filter, RC valve, hell just check everything associated with intake combustion and exhaust. I just went through all of this and found the crank seals were worn and the S-9 jet nozzle is too rich. I found out by accident when I ran the bike with the gas off, as it ran low on fuel the pressure in the bowl dropped and it cleaned up nicely for a few good whacks on the throttle. After installing the smaller 2002 CR125 TMX carburetor on my 02 CR250 I was stunned to find it ran 10 times better, so...I just ordered an S-7 nozzle for a YZ125 TMX carburetor from powersportsplus and I'm waiting for it to get hear so I can fine tune the jetting (or die trying) http://www.powersportsplus.com/parts/detail/yamaha/YP-3TC-14141-S7-00.html Just be sure not to run too lean or you will toast your top end (Read your spark plug color, brown/tan =good, white/gray=bad)
  13. Yamahondaha

    Help 2002 CR250 Carb Trouble

    How about an S-6? http://www.powersportsplus.com/parts/detail/yamaha/YP-3TC-14141-S6-00.html I ordered an S-7 from Powersportsplus today along with a few other things I needed to add up to just below $60 to take advantage of the $6.95 shipping.
  14. Yamahondaha

    Help 2002 CR250 Carb Trouble

    Thank you for the info, I will check with my local Yamaha dealer first but I will get the S-7 first. On a similar note I read somewhere that the non-removable nozzles are actually removable. The poster wrote that he unscrewed the part above the jet and pressed out the top part then filed the small pin that was holding in the nozzle, once it was all removed he was able to screw in a replaceable nozzle. If I run across the post I will link to it.
  15. Yamahondaha

    Help 2002 CR250 Carb Trouble

    As it turned out it did get me somewhere to compare the two. My 250 ran so bad that I wasn't even close with the stock settings. I was hoping to find my 125 had leaner than stock jetting so I pulled the 125 carb out and had a look inside today. Just for fun I installed it on my 250 and it ran so much cleaner that I had to find out why. I put both floats in a can of gas and they both floated to the same height so I ruled out my previous theory. Most shocking to me was the 420 main jet (20 over stock and 40 more than the 250) everything else was stock. I was able to install the 125 needle in the 250 carb and it ran good but still overall it was rich. I read some great info on this site http://www.bogord.com/2010/10/jetting-mikuni-tmx-s-7-nozzle-swap-2001.html that has put me in the direction of the nozzle. I have had a needle seat wear out on an old XR from the 70's so I'm wondering if 10 years could have worn the nozzle enough to put it out of spec? I am going to order an S-8 nozzle based on what I've read on Bogord.com just because temps here are over 100 these days...
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