Rpm question

Discussion in '8th Generation 2014-Present' started by Trailwart, Apr 5, 2019.

  1. Trailwart

    Trailwart New Member

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    2015 deluxe. I am learning this bike and have searched but have found no answer. Is first gear rpm limited under 7-8 k rpms. Seems like the bike bucks/ pukes around there. Almost like valve float.
     
  2. Allyance

    Allyance Insider

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    Are you letting get up to temperature? Should be at about 142 before V-tec will work. If not warmed up it will cough and sputter till it gets somewhat warm, I don’t know exact temp, but I always wait till it get over 120 before starting out.

    First gear is not limited, I gotten frisky and wound it out to over 10K no problem.
     
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  3. Thumbs

    Thumbs Member

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    There’s definitely not a rev limiter on the RC79 below the redline, I’ve taken my to the line a few times and no problems ...but always after a few minutes riding, I also warm it up until the revs start to drop before setting off

    I’m inclined to agree with Allyance that the motor is not hot enough

    6,700 is where the VTEC cuts in, should be smooth by 7,000
     
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  4. fink

    fink Insider

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    Only when the engine is cold, the vtec doesn't kick in or something like that. Once up to temp it will be fine. As your initial statement provided no info bar revs I took it as from initial start up.
     
  5. Trailwart

    Trailwart New Member

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    Wasn't up to temp. Did some riding today and verified that I wasn't up to Temp. All is well when it is warm. Thanks again
     
  6. mikem317

    mikem317 New Member

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    I experience some hesitation early in the RPM range from a cold start and immediate take off. I learned to just let the machine warm up a bit. I will wait until there's a temperature read out on the display before starting out and that helps out a lot.
     
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  7. zroger73

    zroger73 New Member

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    I bought a new 2014 several weeks ago and noticed this. I've never owned a fuel-injected motorcycle - let alone one with VTEC. The first time it happened, I thought there was something wrong with it, but it's comforting to know it seems normal/typical for this model. Runs great after just a few minutes of warm-up, but it can be contrary until then.
     
  8. katatonic

    katatonic New Member

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    Why are you all thrashing on a cold engine?? That has the potential for so much damage!
    Even if the coolant is registering as somewhat warm, it takes a good amount of time to heat-soak the engine and get the internals up to proper operating temperature.
    Where do you have to be in a hurry that your WOT on a cold bike? Even if you are legit in a hurry and HAVE to start riding right away, take it easy for the first 5-10 minutes!


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  9. mello dude

    mello dude Member

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    Yes! Exactly!
     
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  10. Bubba Utah

    Bubba Utah Insider

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    I thought that VTECH needed to be up to around 155-157 degrees. I just let mine idle until it hits 155 and never have had a problem. With all of the shit that I have had with mine. I let it talk to me for a while and drink a cup of coffee before heading out. She has been a little temperamental at times. ;-) She's a hot head, but she is a red head as well. :wheelie:
     
  11. NorcalBoy

    NorcalBoy Member

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    There are myths, there are legends, there are habits. A modern engine has max oil pressure within seconds of starting and modern oils don't "thicken" when sitting. The best way to get an engine to full operating temp is under load. Ask any manufacturer off the record and they will admit it doesn't really matter either way. Common sense is the X in the equation.
     
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  12. fink

    fink Insider

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    I can remember when the Aprillia Rs has to be warmed up before using.
     
  13. Allyance

    Allyance Insider

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    NorcalBoy is correct about the oil pressure, in the case of the gen 8 VFR800, engine temp controls the performance and the ECM controls the fuel injection until a certain temperature is reached. If you start out too soon before getting up to temperature, the engine just bogs and could put you in danger if you need to get out of the way in a hurry. My old SUV will get up and go from a cold start, the gen 8's have this quirk and it doesn't take long to get up to the proper temp. In this case it is not a myth or legend, but a fact of life. I have had my 2014 four and half years and it still does it. Maybe newer models have an updated ECM. Anybody have a different bike with fuel injection that reaches full performance from a cold start?
     
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  14. katatonic

    katatonic New Member

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    You are correct about engines getting up to max oil pressure pretty quick, but the internals are not up to optimum operating temperature for a good 5-10 minutes of light riding.
    There are many parts in the motor, especially pistons, that swell up when heated. The piston-to-sidewall clearance is going to be smaller once the bike is up to temperature so the piston will fit better in the cylinder once it's done expanding. But when it's cold the piston-to-sidewall clearance will be bigger and the piston will tend to rock back and forth in the cylinder. This can lead to damaging the piston, cylinder, seals and pretty much any part of your engine.


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  15. XRedJar

    XRedJar New Member

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    Modern oils do still thicken when cold, but I think to your point is it's not like it used to be 20 - 30 years ago. The flipside is that tolerances in engines (ok...maybe not the VFR because of the age of design) are tighter too. So it still makes sense not to horse on a cold engine. The film strength should protect parts enough on cold start, but going straight to WOT/redline is still not a good idea.

    Agree that once you get some temp in the engine (30 - 60 seconds running), best thing is to ride out under load, light load. That will build heat in the motor progressively and quickly. By the time I'm out of my neighborhood and hit the big roads, I'm good to go.
     
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  16. Allyance

    Allyance Insider

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    I think we are talking about two different scenarios; one, wear & tear due to engine temperature and two, the affect of temperature on the ECM and the fuel injection system. I have tried to hurry the warm-up and the engine definitely bogs and stutters. I have never seen engine do that die to oil or clearances. It is more like a carburetor engine without enough choke.
     
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  17. 34468 Randy

    34468 Randy Secret Insider

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    I have let mien warm up very occasionally. Normally, I fire it up and away I go. Not like a jack rabbit or anything but s far as I have experienced, the need to warm the bike up before riding it has not been necessary for me. 218,000+ km and the engine still purs. I still do have an issue of rpms spiking when cold taking off from a stop in first gear though. Next thing I am going to try to resolve that is replace the throttle body. I've tried just about everything else including leaving it with the dealership for several weeks and paying mucho bucks for a temporary relief.

    I will get at that some day I hope.
     
  18. Allyance

    Allyance Insider

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    My 6th gen (2003) was like yours Randy not too fussy about temp, easy starts till warm. I did have a POwer Commander which made a big differenc below 3K rpm.
     
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