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    • Bryan Bosch

      JUST IN!   07/18/2018

      Video: 2019 Yamaha YZ250F Features & Benefits 


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  1. Special tool coating? Like titanium nitride? Hard chrome? Ramp angles to steep for the valves? Isnt that the springs job? It seems as though i have been getting heads with valve seat concentricities of .003 sometimes more!!!! These are heads that have had previous valve jobs. Yes i was brought to my knees with a serdi that was delivered with a leak, noy allowing proper float when centering. .0001 valve seat con gages are hard to find. I myself found not holding very good #s until improving the clamping and floating design of the serdi. I think heads are destroyed with unconcentric seat cutting and to much depth(thus lowering spring tension) resulting in the obvious
  2. Cmon how can you say that!!! You speak with no facts. Do you know the material used in a kw valve? Do you know the material in a ferrea valve? Is there any diff? How come its always the oils fault or some easily blamed item for a failure? We use kw products and find them to be very good products. Anybody who has star swiss machines and good programing and machine operating skills can hold tenths. Do you know what a tenth is? I invite you to come to my shop for measurment lessons. Jim
  3. Im Not Diggin On Ya Or Anything, But Didnt The Seals Cost More Than Half The Price Of A Seal Driver? How Many Seals Could You Ruin To Make That Seal Driver Not Worth It?
  4. All (that I Have Checked) Current 250f,s Run A 55 Leak Or Bleed Jet STK
  5. Ok Think About This- Pre-load I.e. How Much The Spring Is Compressed From Its Free Lenght Controls Primaraly The 1st 1/3 Of Travel. Spring Rate Will Primaraly Control The 2nd Third Of The Stroke. The Last 1/3 Is Controled By Oil Volume. Check How Much Oil Volume Is In Your Forks Or Add Some. Also That Cartridge Is Bled Horizontaly Not Vertically.
  6. There Is One And Only One Cure To Properly Jet Your Cr250. Put The 420 Mj Back In, Std Pilot Then Call Your Local Yamaha Dealer And Have Them Order You A S-4 Nozzle. Your Bike Will Pick Up Almost 3hp Through The Middle And Run Perfect. We Have Ran This Jetting At 0-2000ft Down To 50 Degrees. S-7 Nozzle For Colder Temps. NEEDLE POS IS #3.
  7. You Could Reduce Leak (or Honda Calls It Bleed) Jet Size. You Can Get These From A Yamaha Dealer. I Guess I Didnt Read Ahead. New Guy Here On This Site. I Would Go To A#45.