Pre ignition in 08 C50
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  1. #1
    Newbie
    My Bike(s)
    2008 C50
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    5

    Pre ignition in 08 C50

    Changed back to stock exhaust and now notice I have pre ignition when under load in lower rpm range. Never heard this with baffled Vance & Hine pipes. Have put in higher octane fuel, 91 & 93. Seemed to help but still happens at times, not all the time. Couple thoughts is maybe due to more back pressure or the ethanol in fuel, especially not all the time. And maybe it was always there, but couldn't hear with louder pipes. Any thoughts, thanks

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  3. #2
    M-J Lifetime Achievement Award
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    Yamaha MT09
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    Was the bike (re-jetted) carbs... ( ECU flashed) fuel injection... to suit the pipes?
    Smoke me a kipper I'll be home in time for breakfast

  4. #3
    Super Moderator

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    Quote Originally Posted by ramrider View Post
    Changed back to stock exhaust and now notice I have pre ignition when under load in lower rpm range.
    Raise your idle speed and don't lug the engine.

    If the plugs haven't been changed lately, do that too.
    Make sure the plugs are NOT a higher heat range than stock.
    Don't believe everything that you think.

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  6. #4
    Newbie
    My Bike(s)
    2008 C50
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    5
    Appreciate ECM and plug thoughts. Will pull plugs and inspect, changed them about 3,000 miles ago. Did wonder about ECM change, but don't no how to check. Will say it is more noticeable in low rpm especially under load. Gets quite in higher rpm . Thanks

  7. #5
    Ditch Magnet
    My Bike(s)
    Suzuki C90 & C50T
    Location
    Portland, OR area
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    175
    Quote Originally Posted by ramrider View Post
    Appreciate ECM and plug thoughts. Will pull plugs and inspect, changed them about 3,000 miles ago. Did wonder about ECM change, but don't no how to check. Will say it is more noticeable in low rpm especially under load. Gets quite in higher rpm . Thanks
    Sounds like the valves might need adjustment to me. The factory recommends inspection (which usually means adjust as needed) valve clearances at 7,500, and 14,500 mile intervals...and ever 7-8k thereafter according to the owners manual. I've known folks who never did this at 20k-30k miles and their bikes barely ran. Once they did a valve adjustment it ran like new. Part of the mechanical lifter package we get with the VL800 unfortunately.

    If the other stuff recommended doesn't make any difference, pretty likely it's the valve clearances needing adjustment.

    Good luck.

    Larry

  8. #6
    Newbie
    My Bike(s)
    2008 C50
    Posts
    5
    Set valves about 4000 miles past and yes I do believe an inspection is due. I set middle range and sounded loose when cold from day one. Have set valves on my bikes for years and this is the hardest to do. Also think I got a bad batch of fuel from grocery fuel station even thought high (91) test. Ran a tank of Exxon 93 and cleared up and filled last tank with Exxon 89 and still good on pre ignition under load. Will recheck valves when cooler temps arrive. Thanks for input, Larry.

  9. #7
    Super Moderator

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    Ocala, FL
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    Quote Originally Posted by ramrider View Post
    Also think I got a bad batch of fuel from grocery fuel station even thought high (91) test.
    Except for preventing knocking in a high compression engine, so called "premium" is no "better" than regular.

    In fact, in some cases (many ?) it might even be worse because the turn-over is much less and it's more likely to be old and contaminated.
    Don't believe everything that you think.


 

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