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  1. jaguar

    Octane, Non-Ethanol and Pinging problems

    Royal Purple octane booster definitely works. If you don't like changing crank seals twice as often then don't use gas with alcohol. I made that mistake and now totally swear off every drop of alcohol. But I've heard some seals have resistance against alcohol, the newer ones but I don't know at...
  2. jaguar

    How-To KDX - Motorcycle Carburetor Tuning

    video about a free spreadsheet for selecting a different needle for Keihin carbs:
  3. jaguar

    All About Engine Oils

    There are two ways to determine fuel/oil ratio: 1) for race engines that you want the best power from them you just use a lot of oil, close to 32:1 (of any type oil with a viscosity of at least 2 @ 200*C). You also want this ratio for air cooled cylinders to prevent piston noise. 2) for...
  4. jaguar

    Help 04 Cr85 main jet problem!

    you said the piston is wearing down and it runs rich both of those happen when you don't use enough oil. tell me which oil you use and I can recommend a ratio
  5. jaguar

    carb sizing formula revisited

    OK here's my web page on this that has a link to a free download of a spreadsheet that will tell you the carb diameter needed dependent on engine size and intended use: 2 Stroke Carburetor Sizing
  6. jaguar

    carb sizing formula revisited

    This chart generally shows the velocity thru the carb that the manufacturers selected dependent on the engine size and type of intended use:
  7. jaguar

    carb sizing formula revisited

    Now that I've researched even further I've found it's not as straight-forward as using a set variable formula. Looking at bike specs and figuring out each ones WOT max RPM carb velocity I have "seen the light" and now know that the engineers have been picking flow velocities to match the size...
  8. jaguar

    carb sizing formula revisited

    Redoing The Carb Sizing Formula It seems to me that the formula .8 x square root (engine cc * RPM/1000) came from car carburetor manufacturers and so I wanted to redo the formula based on the carb throat cross sectional area as a fraction of the intake volume of the engine. The intake volume...
  9. jaguar

    Help Issue dt 200 yamaha dying

    take the carb jets out and push a wire through them to clean them out, especially the idle jet since its the smallest. make sure you have good fuel flow to the carburetor and that the float valve is working correctly
  10. jaguar

    Help 04 Cr85 main jet problem!

    what oil you using and at what fuel/oil ratio? make sure your air filter is clean and that the pipe stinger isn't carboned up and restricting flow at high rpm. If you suspect that then take the pipe off, put pebbles in it, and shake it a lot.
  11. jaguar

    Help - Cylinder

    when you replace the piston look at the underside of the piston top to see if its blackened. If so then the main jet is too lean.
  12. jaguar

    new peak power RPM formula

    I've updated my approach to figuring it out. Read about it at www.dragonfly75.com/moto/blowdown.html
  13. jaguar

    Trying to ride a cr500

    Just get a KTM 300
  14. jaguar

    Help Issue dt 200 yamaha dying

    turn the idle air screw till it has the highest RPM then turn it 1/4 turn clockwise then turn the throttle slide stop screw till it idles at the correct RPM
  15. jaguar

    Newbie here named Claude from Canada

    girl + little experience = crash
  16. jaguar

    Yamalube 2S or 2R?

    2R is made of 60% group 3 oil which is highly refined petroleum oil that is good enough to legally be called synthetic. But a typical ratio to use it at is 26:1 so expect more smoke and spooge but really I am favoring group 3 oils more than any other right now (for their protection and increased...
  17. jaguar

    The Famous Oil Ratio Test Article - Where is it ?

    Rick Sieman: SuperHunky.com "A second test they performed was to run synthetic in two identical engines and one was run at 24:1, the other was run at 50:1 The engine that ran 24:1 had less piston skirt wear, and less rod bearing wear, but had the same main roller bearing wear as the...
  18. jaguar

    Looking for first dirtbike (with some questions

    the kill switch grounds the stator coil output (to the CDI) when you press the button. You could run that same wire to a switch that grounds it to the frame/handlebars when the key is removed.
  19. jaguar

    Synthetic or Mineral Engine Oil for 2 Strokes?

    Husqvarna did some testing in the mid 70's that was very interesting. They put 3 identical stock engines on a dyno and ran them for several days at varying RPM and load conditions. Then the motors were torn down and inspected. The engine running CASTOR based oil had the least wear, followed by...
  20. jaguar

    Synthetic or Mineral Engine Oil for 2 Strokes?

    Also Yamalube 2R has about 60% group 3 oil and most everyone loves it. Here's a report I found on the internet about how more oil increases power: "I have run Dyno tests on this subject. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially...
  21. jaguar

    Looking for first dirtbike (with some questions

    all motorcycles should be locked to a pole with a strong chain. you can hide a GPS tracker on it also to find it after it is stolen.
  22. jaguar

    Piston help. Newbie

    the piston skirts were blackened due to the blowby past the stuck ring. make sure the filter is clean and oiled. usually you can recover a piston like that. just make sure there is a little vertical play for the ring. you can use an exacto knife to scrape the surfaces. the black under the piston...
  23. jaguar

    98 cr250r lost compression

    Usually a blown head gasket will cause an immediate change like that. Rings gradually wear down. Only snagging a ring on a port can cause an immediate loss of psi. But check that the spark plug didn't unscrew.