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About MotoSenior

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  1. I am running the 290 kit with head porting for increased flow. I had to drop the main and idle jets. I think the general rule is that the more flow (suction), the leaner you'll need to adjust your carb. As mn519 says, start with your stock jetting. Ride the bike at a good pace with the throttle open, then stop and check the plug. It should be burning a tan color. If it is sooty, reduce the main jet size until you get a good tan color. You should always re-tune the fuel screw with the engine fully warm each time you change any jets. The pilot jet is running too rich if the motor stumbles and stutters as you crack the throttle open (first 1/8th turn), an then cleans up as you continue to open the throttle. Reduce the pilot jet size until you get a crisp clean response in the first 1/8th throttle. It might take a few iterations, but you can make theses changes through the port in the bottom of your float bowl without removing or tilting the carb. Once you have the jetting dialed-in, your big bore will rip! Well worth the effort. Good luck.
  2. MotoSenior

    2010 YZ250F - big bore or modify??

    I got a great deal on a new 2009 YZ250F and put the savings into an Athena 290 kit, head porting, 2005 air boot (they were larger diameter back then), and a pipe. Both the main jet (160) and pilot jet (40) needed to be reduced, but I'm at 5000 feet, so don't use my numbers at sea level. The pilot made all the difference in throttle response. I only have about 4 hours on the motor due to snow, but it is not exactly what I expected. I expected a mini 450, but it's really closer to a 250 two stroke. Plenty of low end pull, but a really substantial mid-range hit. I might need cams to coax a little more rev out of it, but then I don't really want the engine to blow up either. Well worth the effort and $. The bike is a blast on the track and promises to be great off road. Good luck!
  3. MotoSenior

    How's Berthoud track look?

    Even though they are putting a lot of effort into clearing snow and prepping the track, it's going to take a few warm and sunny days to get the ice and snow off the track. We rode today and could only put in a few, very slow laps before calling it quits. I'll spend tomorrow cleaning the bikes.
  4. MotoSenior

    Grand Junction This Weekend?

    Thanks for the report TJ. Unfortunately we had to cancel due to mountain driving conditions. Thanks again for checking riding conditions for us.
  5. MotoSenior

    Grand Junction This Weekend?

    Thanks for the update TJ. Nice pics!
  6. MotoSenior

    Grand Junction This Weekend?

    A group of 8 of us are planning on heading over from Denver this weekend, Feb 16/17, to ride behind the airport, or even Rabbit Valley. I would appreciate any locals who could give us an indication of what the conditions will be like after the Tues/Wed storm. As you probably can imagine, us Denverites are going stir crazy with all the snow. I drove down to Aztec in Colo Spgs on Sunday and there was no snow. The track was great, as was the weather. It was great just to ride again! Any posts on Thursday would be greatly appreciated - thanks for your help.
  7. MotoSenior

    '06 YZ450f leaking water pump

    I haven't experienced this personally on any of the Yamaha's I've broken in, but I hear that the seals break in with wear and don't really function that efficiently until they do break in. I'd give it some time and see if it's still a problem.
  8. MotoSenior

    Riders in and around Denver

    Thunder Valley is west of Denver on C470, just south of the I70 junction. Go to the following web sites for info on Colorado tracks: http://www.rmxa.com/ http://www.cosportsriders.com/ http://www.mxthundervalley.com/ Good Luck!
  9. MotoSenior

    Riders in and around Denver

    Shout! Aurora
  10. MotoSenior

    06 450F - Strange Vibrations

    Thanks for all the advice. Yes, I did a visual inspection, but didn't check torques prior to the break-in ride (lesson learned there). I did go through the entire bike after that ride, and yes I found some under-torqued nuts and bolts, but nothing about to fall off. The sprocket bolts are fine. I'm going to take a hard look at the wheel bearings, the axle, and the counter-shaft before I take it to the dealer. I'd like to go in with a specific problem rather than a noise. Thanks again for the feedback. I'll let you know what I find out.
  11. I was able to take my new 06 450 out this weekend to break it in (by the way, I love it). While taking a few mellow break-in laps, one of the chain adjusters loosened-up and the axle slipped. This caused the wheel to become misaligned and the chain to go really slack. I took the bike home and removed the rear wheel to inspect. Everything looked fine. I went back out today and noticed that when I decelerate, I "feel" a strange vibration. If I pull in the clutch it goes away. My gut feel is that it's coming from the engine. If so, I suspect that the counter-shaft bearing may be bad. Any ideas? Since it's brand new, I'm going to take it to the dealer. Otherwise, the bike is GREAT! Feels very much like a 250F with more power. Well worth the wait.
  12. MotoSenior

    Fork Seal Leak

    You have to replace your fork seals (do them both at the same time). If you haven't done this before, you might want someone who has to go through it with you the first time. Otherwise, remove the forks and take them to your dealer. After a year of riding, it's not a bad idea to change out the fluid anyway. Hope this helps.
  13. MotoSenior

    06 450F Front Tire

    I really appreciate all the early reports from you lucky few who are riding your new 450's while I'm waiting for mine to come in. I would like to hear your personal opinions and experiences with the infamous 739 front tire washout. I'm trying to decide if I should chuck the tire before I ever ride it, or risk the broken collar bone to see if the front end still washes out on the '06.
  14. MotoSenior

    When Is It Coming!!!!!!!!!!!!!!!!11

    They're starting to trickle into Colorado, but very slowly. Of course it's supposed to be in the single digits this week, but there's room in my garage.