RPM? Tach?

Discussion in 'General Questions' started by jraice, Dec 19, 2007.

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  1. jraice

    jraice Guest

    I hear about max RPM's and such and how would you know what your engine is running at???

    Is it recommended not to give it full throttle?

    Talking 70/80cc 2 stroke....


  2. I use a SenDec (sp?) tach....I have had the Dax 70 to 6300 RPM but I wouldn't want to run it anything at or above 6K for extended periods of time to.....Maybe I'm chicken but I didn;t wanna blow the engine (lots noise vibes at that speed)....For faster speeds at a more reasonable engine RPM I'd use a smaller rear sprocket.....I have a 36T on my bike and it'll go about 34.4 MPH at about 6100 RPM.....I probably could gear a little higher and still be ok tho.

    Oh....I have read that many people use full throttle but make sure your engine is broken in first, use enough oil in your mix and try not to over rev the engine (almost impossible if you go full throttle all the time unless you change the gearing to run at moderate RPM's)...Engine life should be longer at moderate rather than insane engine RPM's.

    Hope this helps.

  3. jraice

    jraice Guest

    Okay proper break-in would be two tanks of gas or so at moderate speeds currect?

    Hmm any links on the tach? Ill try and find it...

    This thing is going to be cool :).. Speedometer, tach, mirrors...
  4. Skyliner70cc

    Skyliner70cc Active Member

    I run nothing but full throttle, max rpms, on my engines almost 100% of the time with NO problems. I use a castor based lubricant mixed at 5 oz/gallon.

    As for break in, this topic has been covered millions of times here. Moderate speeds won't help break in. Varying engine load over a wide variety of engine load/rpm ranges is what is important meaning high rpm high load should be part of the break in process.
  5. jraice

    jraice Guest

    Castor Lubricant?

    Go on?

    I assume thats different then the 20-1 or 25-1 2 stroke oil ratio?

    Ill search for my break in info, thanks...

    Reason I said moderate speeds is because I know on a real motorcycle engine the break in schedule would be something like this...

    4000rpm for 500 miles, 6000rpm for 1000 miles... I think thats Kawasaki's... I know it recommends 4000rpm for the first set..

    Anyways, I guess these motors work differently!

  6. Skyliner70cc

    Skyliner70cc Active Member

    I don't follow manufacturer recommendations that limit RPMs during the break in process. The key with any engine is vary engine and rpm to seat the rings and other internals. Any new engine of mine, motorcycle, car, weedwhacker, snowthrower, will see redline on its first run once warmed up.

    As for castor oil, it creates a varnish that acts as a lubricant and when overheated actually forms compounds that lubricates better. It can tolerate extreme temps and pressures far better than any synthetic 2 stroke oil.
  7. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:JMO, I would rather run by tach than speedometer, with my high rpm engines. I'd like to run my engines at peak torque range, than beyond max rpm limit.

  8. jraice

    jraice Guest

    Whats the peak torque range for these engines?

    That one looks nice, I also checked out SenDec's unit...

    I think I am going to get a tach like that and then an analog speedometer... I dont mind the lagging (2 second) tach but analog speedometers seem to be smoother then the lagging digital units... Plus it looks pretty cool (analog)...
  9. sparky

    sparky Active Member

    Wuhho!! $37 is CHEAP!!

    I always wondered how people knew their RPMs.
  10. KiDD

    KiDD Member

    I'm gonna have to buy one....
  11. loquin

    loquin Active Member

    BTW: Dave Staton has a nice little tach/hour meter at staton-inc.com