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Recent content by oab

  1. oab

    MotoGP - coefficient of friction 55¦=1.4

    crysta1c1ear "Is 1.4 coefficient of friction for a motoGP bike's tyres and a 55 degree lean on a horizontal bend feasible?" Well when you see them doing it,, I guess it is.lol I am probable not going to explain this too well, but. When you bank a bike over, you move the center of gravity...
  2. oab

    Replacing tires on all wheel drive vehicles

    My experience with AWD is confined to the Subaru types. Both the Transfer clutch type and the Varied Torque Differential type all detect a difference in wheel speed of more than 20% as wheel spin, and apply the clutch to reduce it. This has a pronounced effect on low speed tight turning, as the...
  3. oab

    What's the real purpose of stepped headers?

    This is a good read on the subject. www.fh-zwickau.de/ftz/Konferenzen/muenchen_2003/htm/Papers/10_Costa.pdf - Harvey.
  4. oab

    Solenoid valve resistance different

    A lot of automotive control solenoids are operated by a Duty Cycle, even if they are an on/off operation. This is so the controller can tell if the armature is responding to the signal. It uses the Inductive feedback, that varies with the armature position, to tell if the armature is moving to...
  5. oab

    Perimeter front brakes

    Giday Richard, I think the main reason that it is not used in sports bikes, is the added gyroscopic effect that the perimeter disc has on the steering response, it inhibits a fast change of direction. It’s the same reason that we don’t use 21” front wheels on sports bikes anymore. Harvey.
  6. oab

    Brake Mounting location

    With motorcycles, the caliper is mounted at the rear, to bring their mass in line with the steering axis. When they are mounted at the front, they add to the steering pendulum effect. Not so important on cars. Harvey.
  7. oab

    Motorcycle steering

    Quote Skenn( OK, so I was wrong...weight shift can make it turn .. depending on the (geometry)?)Quote. Depending on speed. Quote Skenn(Hanging off can't affect lateral load. That is purely mass and angular velocity. It only affects how far up the side of the tyre the load acts.) Yes that...
  8. oab

    low down torque TT500

    Good to see you have got the project back, Malcolm. Harvey.
  9. oab

    Fijnger Followers

    "One note is that the Ducati engineers agreed the Desmodromic head is just part of the sales mystic of Ducati." Oh,Oh, how can you say such a thing:-D? You really have to build a Desmo engine for racing, or race one, to appreciate the worth of the system. Valve durations and lift can be...
  10. oab

    proper exhaust dimeter

    Knap says,,, "Exhaust tuning theory is actually fairly simple, it’s all about getting the negative (and, hence, scavenging) pressure pulse to arrive at the exhaust valve as it is opening." As there is about 60 to 70 psi still in the cylinder, when the exhaust valve opens, what difference is a...
  11. oab

    Exhaust X-Pipe location and Resonance Question??

    I think the resonance is being produced in the rear pipes, hence the reason for the resonators fitted as standard. Fitting a crossover pipe up closer to the exhaust valves, is not the way to fix the rear resonate problem, it can hurt performance by allowing high pressure gas pulses to reach the...
  12. oab

    What makes a shift "sporty"?

    With an auto, while the transmission computer cuts the torque, during the change, it will always be slow. To have the change made faster, the torque cut can be deleted, but you have to ensure that the Trans computer does not lower the line pressure during the change, as most do, or a...
  13. oab

    Questions on camshaft LSA and overlap

    The Lobe Separation Angle, is the end result, not the starting point. You choses the duration and lift. to suit the rev range that the engine has to operate at. You set the inlet lobe center to correspond to the maximum air speed rpms. Set the exhaust lobe center to suit the exhaust needs, to...
  14. oab

    Calculation For Intake runner length?

    The 80/90* depends on cam timings, and is used on engines at higher rpms. As the inertia of the shorter gas column can move faster.. The sonic wave starts at the inlet valve opening, travels to the end of the track, to reflect back as a positive wave, meets the piston 80/90* down the stroke. The...
  15. oab

    Why machine brake rotors?

    Surestick, It is not just the small amount of air escaping from under the pad, that produces the sound. If that was the case, the noise would be there without the disc rotating. It is the boundary layer of air, that rotates with the disc, that is being forced under the pad, that causes the sound...
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