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    • Bryan Bosch

      JUST IN!   07/18/2018

      Video: 2019 Yamaha YZ250F Features & Benefits 


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About MattR

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  1. You may want to try the NGK iridium plug (CR8EIX) before making any jetting changes. The 4-5K rpm stutter at constant throttle that you described in very common on the SM/TE610. Riders have found the iridium plug typical cures this stutter or minimizes it enough to be negligible. By the way, I have running the same exhaust setup with JD kit. My jetting is red needle (#5 notch), 180 main, 45 pilot, 2 turns out, 60 leak jet. In Fall or early Spring, I may run the blue needle if temps are cold enough.
  2. RB-Designs does carb work (both bore and divider plates). http://www.rb-designs.com/bore-plate-carbs.htm I read excellent reports about his work from GasGas and Husky owners.
  3. Thanks for posting the pics of the carbonfiber skidplate. I've been wondering how it holds up to impacts & scraps.
  4. I'm interested to see pics of a used CF skid plate.
  5. Not wide open, but about 1/4 to 1/2 throttle works for me. I suspect that why this works is that the slide is opened more and allowing more air to the mixture. Yes, you are also adding more fuel, but it is already flooded. So by moving the slide to a more open position, the mixture will become more lean and allow it to ignite. Just thinking out loud here...
  6. Yes, it smokes more only at first start up but it doesn't alarm me since there is probably a bit more oil concentration in the older fuel. It dissipates quickly (approx. 1 minute). Then, any later restarts throughout the day are normal. I only lean the bike until I get some initial dribble. Then, I know the carb has a splash of new fuel. I never felt motivated enough to make a huge puddle on the ground and see the pros/cons of starting it differently. Oh, another little drill that I do... I hold my kill button and cycle the kickstarter gently with two kicks. IMO, I'm doing this to lubricate the cylinder wall and build up an initial precharge pressure. Then, I release the kill button and give one kick... 99.99% of the time the bike fires up with one kick. If she's feeling a bit cranky from her bumpy ride in my pickup truck then I give her another kick.
  7. I always "lean" my 2 stroke bikes to give the carb a fresh mixture of gas in the float bowl. I only do it on cold start ups after the bike has sat a week. The old premixed gas that sets in the float bowl begins to evaporate the gas. This makes the overall mixture more lean since there is now more air to fuel during startup. Also, my jetting is spot-on so after the bike warms up to normal operating temps it runs like a champ. When warm, you just kick and go... no issues.
  8. That's a nice mod. Here is the post of your pics for others to quickly reference. http://www.thumpertalk.com/forum/showpost.php?p=8918216&postcount=15
  9. I think that MX Action article is a misprint. 6FBY43-74 would be a half step leaner than the 6FBY42-74. I don't own a YZ125 yet, but from what I am learning from the Yamaha shop manual, the -74 is a 2.74mm OD needle. The 42-xx is standard, then the 43-xx is half step leaner, and 44-xx is half step richer. Hopefully, someone else will confirm this. I'm used to the Keihin PWK carbs and trying to learn about the Mikuni TMX's.
  10. Thanks for the input on the approx. $300 rebuild cost. That is kind of what I figured with new spokes, rim, and labor costs. Well, I did some searching on Yamaha's website. So hopefully this helps out other folks with a similar question... I compared the Yamaha part lists for some 2009 bikes. It appears that the WR250F and YZ125 have all the same parts (except rim and spokes of course). So it would be a direct fit using the same wheel spacers, axle, axle blocks, etc.. I'm happy to see this! This will allow me to look for a "used" 18" WR250F wheel on TT, Ebay, or other sources. Hopefully, this would be a cheaper route than the $300 rebuild with OE hub. An interesting find was that the 2009 YZ250F/450F use a different hub than the 2009 YZ125/250, even though both are running 19" wheels. So, the YZ125/250 are using the same hub assembly from the WR250/450. FYI... A complete rear wheel from aftermarket companies like RAD Manufacturing start about $375 and go up quickly with type of hub. So this route would be least favorable.
  11. What is the most cost effective route for putting an 18" rear wheel on the YZ125? 1) Would the WR250F rear wheel fit directly (same axle, etc.)? 2) Buy an aftermarket rear wheel assembly? 3) Or rebuild with the OE hub?
  12. Thanks for all of the responses. The YZ125 sounds like a fun bike on singletrack trails. The more I thought about my height concern, the more I realized it is a non-issue. Just look at David Knight or Geoff Aaron. Both are much taller riders that make bigger bikes such as the 250/300's look small. So a bit more height on the YZ125 might not be a bad thing.
  13. Thanks for the information. What is your size and weight? Any adjustments needed for someone 6 feet tall? I believe the stock spring rates in fork and shock should be ok for my weight (based on RaceTech's website). What spring rates are you using?
  14. I'm considering a 2009/2010 YZ125 for enduro riding. I used to ride a KTM 200EXC before my current GasGas EC250. I really miss the smaller bore riding style. I have been doing a bunch of research and I think the YZ125 will be a great bike for me. I'm 6ft tall and approx. 175 lbs with gear. How will the stock suspension and bike setup be for my height/weight? Any other mods needed for the handlebar position or taller seat? Thanks!
  15. The numbers indicate its a 2001 XC250. The XC was imported into the US with lighter weight ignition 2K-2. This is like the KTM with XC trim package. The lighting coil is 35watts to run basic headlight/tail light. These bikes have an abbreviated wiring loom with typically an on/off light toggle switch on the headlight shell. Of course, the previous owner could have swap the ignition to the heavier 2K-3 with more lighting output. Without you posting up pics (closeup of left side engine), it's really a total guess from the VIN numbers.