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Thread: My Mana No Longer Vibrates In Sport Mode

  1. #1
    apriliaforum newb
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    My Mana No Longer Vibrates In Sport Mode

    The road tests almost always pointed out that the Mana vibrated in Sport Mode - that is, full auto with Sport mapping.

    One tester even said she was glad the fuel range was small because she needed to get off the bike after an hour and a half of tiring vibration.

    Several testers commented on vibration from the left footrest, especially. And especially in Sport mode.

    I found it incredibly smooth, for a no-balance-shaft, v twin engine - just a pleasant, very slight v twin shake coming up at cruising speed, if any time. This included several hours cruising at 90 mph in Wyoming last year. I have taken it faster than that, without noticing vibration.

    Except in Sport Mode.

    I would occasionally switch into Sport Mode from Sport Gear (manual selection of each ratio, 1 to 7) and I could immediately feel that vibration. Various people said that it was due to the engine being allowed or required to rev higher before changing the belt ratio.

    It's true that that was happening, but for a long time I also knew that the higher revs were not the cause of the vibration, because holding it in a particular ratio in Sport Gear (manual ratio selection) and taking it to the red rev-limit light didn't give vibration.

    A number of people had also said that there was a slight power advantage in Sport Mode and so I decided that the engineers had probably advanced the ignition timing slightly to get that extra surge. One side effect can be increased vibration.

    Yesterday the vibration in Sport Mode stopped on my Mana, after I fitted a GPR Trioval muffler and collector box. It is slightly noticeable but not objectionable on smooth roads below about 50 mph. At 70 mph I now cannot tell by feel which mode I am in, whereas before it was very obvious at any speed.

    I think that the weight and mounting of the oem muffler system is the cause, especially because of the two anti-vibration mounts, one on each side, which connected the collector box (which is in one piece with the exhaust) to the footrest mounting plate, about an inch away from the footrests themselves. The GPR system does not connect to these points.

    It would be easy to test this out by reconnecting the oem system, but I'm not going to do that. Instead, I'm going to enjoy my ability to easily go into Sport Mode at any time, without the menace of extra vibration.

    Has anyone else found this?

  2. #2
    apriliaforum prov-nov
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    Mine already had a GPR can and collector box fitted when I bought it and I've never had any of the vibes you describe. So maybe the factory set up is the cause.
    Al.

  3. #3
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    Well mine came with the GPR can and collector box fitted when I bought it as well but it didn't have the OEM footpegs fitted as it had a set of MFW Supergrip pegs and I could definitely feel more vibration through the pegs when I changed from touring mode to sports mode or Sports Gear mode as it got to the point where I couldn't ride for more than a hour before my feet felt like they were going numb from the vibration.. I have since replaced the MFW Supergrip pegs with a set of MFW Multigrip pegs which seem to damper the vibrations down a bit but I can still feel in when change between touring mode to sports mode or Sports Gear mode..

  4. #4
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    Quote Originally Posted by tinykxb View Post
    I could definitely feel more vibration through the pegs when I changed from touring mode to sports mode or Sports Gear mode as it got to the point where I couldn't ride for more than a hour before my feet felt like they were going numb from the vibration...
    Have you checked chain adjustment?

    The chain MUST have at least 28mm of slack at the tightest point.

    If not, you will definitely get vibration.

    My Mana has slight rumbling vibration (not annoying but you can feel it) at maybe 40 to 50 mph, but it is uncannily smooth at 70 to 90 mph, except this last weekend when I carelessly adjusted the chain to only have 25mm at the tightest point. I had to re-do it on the road.

    Chains are funny - if they are slightly tight they run hot, which expands the centre pins and takes up the slack between the pin and the bush, which effectively shortens the chain even more.

    In other words, a slightly tight chain will actually get tighter because of the heat from increased friction in the inner bearing pin of each link.
    Last edited by Trevor G; 06-06-2019 at 10:03 AM.

  5. #5
    apriliaforum expert AndyT's Avatar
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    There is bound to be some change in feel to the bike between touring and sport modes as the engine map and gear change are different. I haven't noticed any increase in vibration in sport mode, just a difference between the two. It would be worth checking the rubber mountings for the collector box if there is noticeable vibration through the foot pegs.

    I have noticed that my GT has a sort of faint hissing or fizzing noise at speed on quiet road surfaces, which I put down to the belt drive. I also tend to run my chain slightly loose at 30mm+ as I mostly ride in touring mode so backlash during gear changes isn't an issue. As Trevor says, it is very smooth at motorway speeds. Everything seems to settle into a rhythm and you get the feeling it would eat miles all day long.
    2009 Mana GT ABS; Andreani fork cartridges with uprated springs; Dorsoduro hand guards and heated grips; 30mm handlebar risers; Digital tachograph: Modified woodcraft folding brake pedal; R&G frame sliders

  6. #6
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    Well Trevor I have just had my GT serviced less than a month ago in which the chain was adjusted and I had the belt and sliders replaced it in the gearbox and I haven't really tried out with the different gearbox modes as most of the time I just ride it in the Touring mode.. There were times before I had the gearbox belt changed when I would ride it in both touring and sports mode and you could feel a difference in vibrations with it more when switching from touring mode to sports mode which felt really strange to me as my other bike which I use on the weekends doesn't vibrate at all unless there is something seriously wrong with it as it is a 95 Honda GL1500 Goldwing

  7. #7
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    Quote Originally Posted by tinykxb View Post
    ...but I can still feel it when change between touring mode to sports mode or Sports Gear mode..
    I just want to clarify that we are talking about the same thing.

    Sport Gear is where you have to use the for shift or the thumb/forefinger buttons to change gears from 1 to 7.

    Sport Mode is one of the Drive "mappings" in the fully auto mode which keeps the engine revving higher for more performance. The others are Touring and Rain.

    If you feel vibration in Sport Gear or Touring Mode then your chain is most probably either tight (wrongly adjusted without enough slack), unevenly worn (as you rotate the back wheel at a constant speed you will see the bottom row of the chain move up and down as tighter and looser sections are on the bottom run), or poorly lubricated, perhaps with the wrong lubricant, even.

    Your service would not be the first one to send a bike out with an incorrectly adjusted rear chain. It is not unheard of.

    There are a number of ways to check the chain adjustment.

    1) if you don't have a centre stand or a paddock stand to get the back wheel up off the ground and you don't have a friend to help you hold the bike upright, here is what you do.

    Loosen (turn the knob anticlockwise) the rear suspension preload adjusting knob all the way. This will allow you to compress the suspension (to check the chain slack) more easily. Count the number of "clicks" so that you can return it to the same setting afterwards.

    Click image for larger version. 

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    2) Stand on the left side of the bike with it on the side stand, then lie across it using your chest pressing on the seat to compress the suspension as far as possible. While leaned over lift the centre of the chain up and let it drop - if you only have 6mm or so of slack your chain is definitely too tight.

    1a) Here's another way to do it if you only have a side stand and no friends to help.

    Tighten the suspension preload knob (screw it clockwise) and count the number of clicks as you do so that you can return it to where it was when you are finished. Do this until when you push the top of the bike towards the side stand and lift it up to extend the suspension, it no longer compress under its own weight.

    2a) Use a tape measure or ruler halfway between the sprockets at the point shown and measure the distance of the edge of one of the links to the lower edge of the swingarm.

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    In this case the distance is about 65mm.

    Now press the chain upward at this same point and measure the distance again - in this case it's about 35mm. The difference between the two measurements is the chain slack, which is supposed to be around 30mm.

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    3) Move the bike about 0.5m and check again. Chains generally do not wear evenly and you need to adjust or check the chain at its tightest point. Do this at least once more (three measurements all up).

    4) There is another typical chain problem which will cause vibration: partially seized links.

    This occurs when lube is sprayed on the side plates of O-ring chains, or when certain brands of lube are frequently used. One of these, Chain Wax, is known in racing circles to cause this problem (that is how I found out).

    I'll add a pic later of what this looks like. You would need to rotate the whole chain at least once to pick this.
    Last edited by Trevor G; 06-13-2019 at 10:35 AM.

  8. #8
    apriliaforum prov-nov Mike_in_nh's Avatar
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    I have a stock Mana GT, and use sports gear 99.9 % of the time. When in 5th gear I'll get an rumbling sound and a vibration. The sound stays the same but the vibration will change with speed, all other gears are quite and vibration free. My bike has done this since new..

    Nice tip on the Chain Wax.

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