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v7 III rev limiter?

Discussion in 'V7/V85/V9 Chat & Tech' started by JACoH, Oct 18, 2017.

  1. JACoH

    JACoH Cruisin' Guzzisti

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    So, I needed to accelerate quicker than normal the other day, and noticed it was "cutting out" a bit sooner than I expected. Looked at the tach and it was at 5500 rpm! During my 100 mile escapade, I experimented through the gears and in every gear, it started cutting out at 5500 rpm. So, today I checked to see where the "gear shift thresholds" are set, and both Low and High are at 7000, even tho the ECU limits max revs to 7200rpm. Bike seems to run fine otherwise, maybe it's been this way all along and I didn't notice it, perhaps the tach is just reading slow? I was getting ready to do the evap canister mods, but now holding off until I feel ok about this issue.
     
  2. john zibell

    john zibell Moderator Staff Member GT Famiglia

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    Sounds like you need to visit your dealer. Could be an issue with the parameter in the ECU. Only correction I know of under warranty is to replace the unit.
     
  3. JACoH

    JACoH Cruisin' Guzzisti

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    Just an update for you inquiring minds, called the dealer, said sometimes Traction Control #2 does that, but I was in #1, so left it. All I did was the evap hose mod mentioned elsewhere and old blue just wants to rev now. I don't understand it either, but we're happy.
     
  4. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    I have a similar but different event happening. Every time my engine reaches 4,500rpm EXCEPT in 6th gear, a red light flashes rapidly until I drop below 4,500rpm again. Is this a related issue? I can't find anything about it in the owner's manual.
     
  5. vagrant

    vagrant Cruisin' Guzzisti GT Contributor

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    it gets reset by the dealer at the first 900 mile service. it is in the book somewhere because i found it to reset my own.
    might have been in the service manual found here. I did download the pages that I thought I might use someday.
     
  6. Godfrey

    Godfrey High Miler GT Famiglia

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    warning light: It"s in the Owners Manual, Pp 41-42. "Gear Shift indicator threshold"

    The indicator and warning light are set to 4500 rpm when the bike is delivered because you are on break-in and should be observing that as a maximum rpm. They don't prevent you revving higher, but it's a good way to remind yourself that your engine is still new and needs to be run-in properly. After break-in, you can set it to anything you want from 4500 to 8000 rpm, although the computer sets the maximum RPM to 7200 ... setting the indicator to anything higher than that is obviously just turning it off. :) (The dealer will likely set it higher at the break-in service for you, but you can do it yourself at any time.)
     
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  7. Godfrey

    Godfrey High Miler GT Famiglia

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    Another instance of the vacuum regulator valve on the EVAP system failing. I suspect what was happening is that as you went to higher revs, the vacuum tap was allowing too much vacuum to get to the tank. The high vacuum competed with the fuel pump to deliver fuel, so the engine just ran leaner and leaner until it could not make any more power, posing an RPM limit. Removing the vacuum allows the fuel pump to deliver the required fuel pressure so now the engine has plenty of fuel to burn.

    It's sad that the EVAP system is so crappy. This should be such a simple, no-impact part of the emissions control systems ...! It's probably just a matter of how difficult it is to make a cheap, reliable, consistent regulator/charcoal canister and fit it in the space required for a motorcycle. If you look at the ones made for automobiles, the valve is usually pretty bulky and the canister quite large.
     
  8. kiwi dave

    kiwi dave GT Reference

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    Lifted from the owner's manual.

    upload_2017-10-29_8-15-53.png
     
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  9. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    Thanks for that Kiwi Dave. Can the user set where the rev limiter does its thing? I'm a sedate ol' man, so I only found out yesterday that my rev limiter kicks in at 5,500rpm, same as JACoH's.
     
  10. Godfrey

    Godfrey High Miler GT Famiglia

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    The threshold warning is not a rev limiter, it's an aid to tell you when to shift. You can set it to signal anywhere from (I think) 4000 rpm up to 8000 rpm, in 100 rpm intervals. I have mine set to the nominal redline at 6500 rpm.

    The rev limiter is built into the ECU and is set to 7200 rpm, regardless where the shift threshold warning is set. The rev limiter is not user programmable. (Obviously, setting the shift threshold warning to any value over 7200 rpm is how you turn the warning off... :) )

    G
     
  11. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    That's a pity. My rev limiter is kicking in at 5,500rpm.
     
  12. GuzziMoto

    GuzziMoto GT Reference GT Contributor

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    Then you have something wrong.
    The light is adjustable and you can set it as you like. It does not affect the running of the engine.
    The rev limiter is hard set to 7200 rpm or so and is not user adjustable without pre-programming the ECU.
    If you engine won't rev past 5500 rpm you have something wrong, that is not the rev limiter.
    JACoH reports that he had an evap issue and that was why his would not rev past 5500 rpm. Perhaps you have a similar issue, but maybe it is something completely different.
    This might be the evap fix.
    http://www.guzzitech.com/forums/threads/evap-removal-from-v7iii.17880/
    Or not.
     
  13. kiwi dave

    kiwi dave GT Reference

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    I've left mine @ 4500 rpm. Unless I'm paying attention, these minor details of revs past me by. I find that I'm often riding on the motorway stuck in 4th gear when there are two more available. When the light flashes, I might wake up! :yawn:
     
  14. Godfrey

    Godfrey High Miler GT Famiglia

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    IMO, if you are riding along the freeway in 4th gear and the engine doesn't feel like it's strained or overrevving, then whatever rpm is being used is just fine. These V7III motors love to rev and make their best power (using my butt dyno :) ) between 3800 and 5500 rpm, or so. I often find myself moving at a good clip on the local highways in fourth or fifth gear, because that's where the engine is responsive and likes to be. Always shifting up to sixth gear isn't a necessity unless I'm traveling at a higher speed.
     
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  15. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    Whatever it is, it's a clean cut, consistent through all gears and it happens to both cylinders simultaneously. The exact same symptoms are 100% repeatable at any time of day or night in any gear. Hit 5,500rpm and that's your limit!

    My bike has 2,200Km on the clock and has just had its 1st service. Unfortunately I didn't open the throttle that far before the service, but I doubt that such a problem was introduced in that service. No detectable vacuum at all in my fuel tank. As the there are 230Km on the current tank I did leave the fuel cap not fully seated and had another go. It's not the evap system.

    I did reset the gear change warning lights to 6,000rpm and 7,000rpm resp. and I assume they're set there still as there are no change warning lights coming on up to 5,500rpm.
     
  16. Godfrey

    Godfrey High Miler GT Famiglia

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    Gear change warning "lights" (plural)? Far as I'm aware, there's only one with a single threshold setting.

    If your ECU is shutting the revs down at 5500 rpm, that sounds like an ECU re-flash is in order or some other issue is causing the problem. I'd talk to the dealer service folks about that.

    Mine revs right to 6500 rpm (tested my setting on the warning light); I haven't pushed it to the rev limiter at 7200.
     
  17. andyb

    andyb Cruisin' Guzzisti

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    I had a CCM with a Yamaha DRZ400 engine that should have reved to around 9000rpm but kept cutting out at 6000rpm. After a lot of work the problem was......the rpm gauge reading low.
    If the bike is new to you it is difficult to know what speed the engine is running by the sound, so there is a chance that your 5500rpm indicated is actually 7200rpm. I checked my rpm with a digital tacho that wraps around an HT lead and found the problem that way
    AndyB
     
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  18. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    Finally got to checking the tacho - roughly within +- 200rpm (up to 5,500rpm), so that's not the problem.
     
  19. andyb

    andyb Cruisin' Guzzisti

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    Whooops....should have said Suzuki DRZ400 engine in the CCM. Luckily no one noticed
    andyb
     
  20. Dinsdale Piranha

    Dinsdale Piranha Cruisin' Guzzisti GT Contributor

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    Only suggestion so from Piaggio (via my dealer) was to recalibrate the ABS/MGCT. Did that - no avail.

    Would certainly appreciate any reasonable ideas.
     

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