Author Engine noise - only 3500-4000rpm  (Read 663 times)

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  • Offline Coolvirgo54

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    Offline Coolvirgo54

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    • Bike: 2014 VFR1200X
    • City / Town: Bunbury WA
    Engine noise - only 3500-4000rpm
    on: Nov 14, 2022, 07.50 am
    Nov 14, 2022, 07.50 am
    I have what sounds like cam chain rattle or even light piston slap but only between 3500-4000rpm. It's just loud enough to be of concern. That rev range is also where these engines are a little out of balance so maybe its rattling something external or maybe nothing to worry about. Anyone experienced anything similar.

    I think the noise has been there for a long time but has become more prominent since I fitted a new screen. the angle and shape reflects more engine noise towards the rider.   


     2014 CT.  85000km. Mods - De-catted VFR1200F full exhaust with GPR Slip-on, DNA air filter, dyno-tuned to suit with all restrictions removed including top speed, revised ignition timing as well as fuel 10200 max rpm = 138 RWHP and 110ft/lbs torque.                                                                                                                                                                                                                                                                                                                 

  • Offline thetrecker   ie

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    Offline thetrecker

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    Re: Engine noise - only 3500-4000rpm
    Reply #1 on: Nov 15, 2022, 06.17 pm
    Nov 15, 2022, 06.17 pm
    Hi Coolvirgo54,
    At 85000klms, did it have a couple of valve adjustments?
    I ask because, we have 2 CT's here ( my brothers and mine), mine has had valve adjustments in the past, my brothers did not. I can hear ticking in his engine at tick over revs, Pretty sure it's the ticking of out of adjustment exhaust valves, which are known to go out of spec. My engine is quieter at tickover , especially when cold. Both engines had oil and filter changes always before the Honda recommended mileage.

    Tom

  • Offline Coolvirgo54

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    Offline Coolvirgo54

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    • Bike: 2014 VFR1200X
    • City / Town: Bunbury WA
    Re: Engine noise - only 3500-4000rpm
    Reply #2 on: Nov 16, 2022, 04.45 am
    Nov 16, 2022, 04.45 am
    Hi Tom,

    Its not tappets. I have done clearances. Have always had a bit of tappet noise at cold idle but zero noise once warm. Frequency is also too high for tappets.

    It comes in right on 3500rpm and disappears at 4000rpm. It is somewhat throttle dependant Engine has the most vibration under power at that rev range. Sounds a bit like chain noise but cam chain noise doesn't come in and out like that. Also sounds like very light piston slap but behavior is wrong for that too

    Got me beat.

    Cheers

  • Offline thetrecker   ie

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    Offline thetrecker

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    Re: Engine noise - only 3500-4000rpm
    Reply #3 on: Nov 16, 2022, 06.01 pm
    Nov 16, 2022, 06.01 pm
    I can detect a slight harshness around this rev range, I think I know what you describe. I seems that when you increase speed in say 3rd up to this rev and then hold a steady throttle the harshness is heard. It is in the bike from new, It was harsher in the earlier miles, but seemed to mellow a bit after 10k miles or so, also little increased with the Akra can fitted a few years into it's life. I wonder is it the same noise we hear, maybe the balancer shafts singing a harmonious tune at that rev?

    Tom

  • Offline Coolvirgo54

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    Offline Coolvirgo54

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    Re: Engine noise - only 3500-4000rpm
    Reply #4 on: Nov 17, 2022, 12.01 am
    Nov 17, 2022, 12.01 am
    Hi Tom,

    CT doesn't have balance shafts. It still could be harmonics though. good call. I guess I just have to wait a bit to see if it gets worse.

    Dave

  • Offline thetrecker   ie

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    Offline thetrecker

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    Re: Engine noise - only 3500-4000rpm
    Reply #5 on: Nov 17, 2022, 09.35 pm
    Nov 17, 2022, 09.35 pm
    Hi Dave,
    I was inspecting the Doohickey on my KLR650 a few days ago and looking at the timing of the 2 balancer shafts while I was in there, and that made me think about the noise in your CT. Indeed, as you rightly say, there are no balancer shafts in our CT's.
    Ride on and see if it develops.

    Tom

  • Offline Coolvirgo54

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    Offline Coolvirgo54

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    Re: Engine noise - only 3500-4000rpm
    Reply #6 on: Nov 22, 2022, 04.01 am
    Nov 22, 2022, 04.01 am
    Hi Tom,
    I re-read your post and I think you have already given the answer - the clue being the increase when you fitted the Akrapovic.

    "I can detect a slight harshness around this rev range, I think I know what you describe. I seems that when you increase speed in say 3rd up to this rev and then hold a steady throttle the harshness is heard. It is in the bike from new, It was harsher in the earlier miles, but seemed to mellow a bit after 10k miles or so, also little increased with the Akra can fitted a few years into it's life."

    At the same time I fitted the new Givi screen I also fitted a de-catted VFR1200F full exhaust system and already had a BPR can. I bet that's what caused the noise/vibration increase.

    FYI Fitting a delkevic decat 34mm system to replace OEM 28mm system increased RWHP to 128 from 106 std but rear cyl primary headers were still 28mm. Fitting VFR1200F rear cyl primary headers added another 6RWHP. Dyno tune removing restrictions and new timing and fuel maps took it up another 4hp but added massive torque - 110ft/lbs at wheel. 160hp at the engine. 15% better fuel consumption. Fitting the VFR1200F full decatted system (38mm) has added a whole new dimension to the bike particularly above 6000rpm. Putting it back on the dyno in mid-December to see actual results. Increasing exhaust size has had no effect on bottom end torque curve. My engine now has 60% more torque at the wheel than the F at2500rpm and 36% more at peak. 60% more RWHP at 3000rpm, 50% more RWHP at 5000rpm, tapering off to about the same at 9000rpm. It way outperforms an F.

    The only difference between the X and F engines were cam, 2nd gear ratio, tune and exhaust diameter.

    I reckon when Honda changed the cam for better low to to mid torque characteristics for the X they discovered the result was an engine that could outperform the F with a much better balance of power and torque right throughout its operating range, so they restricted RPM to 9200 and absolutely strangled it with the 28mm exhaust to keep a significant separation between the two bikes in the marketplace.








    Last Edit: Nov 22, 2022, 04.03 am by Coolvirgo54

  • Offline BeToney   us

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    Offline BeToney

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    Re: Engine noise - only 3500-4000rpm
    Reply #7 on: Nov 23, 2022, 03.48 pm
    Nov 23, 2022, 03.48 pm
    *Originally Posted by Coolvirgo54 [+]

    FYI Fitting a delkevic decat 34mm system to replace OEM 28mm system increased RWHP to 128 from 106 std but rear cyl primary headers were still 28mm. Fitting VFR1200F rear cyl primary headers added another 6RWHP. Dyno tune removing restrictions and new timing and fuel maps took it up another 4hp but added massive torque - 110ft/lbs at wheel. 160hp at the engine. 15% better fuel consumption. Fitting the VFR1200F full decatted system (38mm) has added a whole new dimension to the bike particularly above 6000rpm. Putting it back on the dyno in mid-December to see actual results. Increasing exhaust size has had no effect on bottom end torque curve. My engine now has 60% more torque at the wheel than the F at2500rpm and 36% more at peak. 60% more RWHP at 3000rpm, 50% more RWHP at 5000rpm, tapering off to about the same at 9000rpm. It way outperforms an F.

    The only difference between the X and F engines were cam, 2nd gear ratio, tune and exhaust diameter.

    I reckon when Honda changed the cam for better low to to mid torque characteristics for the X they discovered the result was an engine that could outperform the F with a much better balance of power and torque right throughout its operating range, so they restricted RPM to 9200 and absolutely strangled it with the 28mm exhaust to keep a significant separation between the two bikes in the marketplace.

    Those are some impressive performance numbers.  In stock form it can already be a wolf in sheeps clothing, purring sedately at 3500rpm and then crack the throttle and run it at or above 6k rpm and she pulls HARD!  Having a significant boost in performance would really be entertaining.
    I don't really have an interest in changing out the exhaust but have had the ECU flashed on all previous bikes for efficiency and smooth operation.  Do you have any experience with JUST an ECU flash and stock exhaust?

     



    arab-exile