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Help Inline 4 slip on exhaust upgrade & FZR250 EXUP valve rattle repair

Discussion in 'Yamaha 250cc In-Line 4's' started by Brandon Otte, Oct 15, 2020.

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  1. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That's great info, remember you do have an adjustment already available to you for the mid range, before changing the main jets which is the needle clip position.

    It shouldn't take too much time to firstly do a plug chop in say 3rd gear or higher, near peak power up to ~16K RPM - read the plug as a first step.

    You need some info as a starting point and short of a dyno session plug chops are the first starting point
     
    ruckusman, Nov 3, 2020
    #21
  2. Brandon Otte

    Brandon Otte Well-Known Member

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    @ruckusman what does a plug chop in 2nd or 3rd gear mean?
    I’m only speculating about feeling it’s down on power. Initially the first ride with the muffler was at night(cold) and first impressions was an increase in power, it is hard though as the sound alone makes me ‘think’ it’s faster. Since then I can’t help but feel it doesn’t quite have that high end pull. I may just be used to the bike now and coupled with higher temperature and humidity is just a case of ‘need’ a faster bike.

    I suppose without actually putting her on a dyno how else would you tell.
     
    Brandon Otte, Nov 3, 2020
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  3. Brandon Otte

    Brandon Otte Well-Known Member

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    I haven’t checked the air filter since owning the bike and have put 1700kms on her now. What’s this chop all about?
    Does it mean a full pull in 2nd or 3rd then pull the plugs and read how they look?
     
    Brandon Otte, Nov 3, 2020
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  4. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Not quite... a true Plug Chop means warming the bike up and then putting in a new set of plugs.. then running the bike at WOT in top gear for a short distance, while still at WOT hit the kill switch and pull the clutch.
    When you come to a stop.. swap out the new plugs for your old ones and take them back to the workshop.
    then get your hacksaw out and "chop" a section of the treads off and "read" the tell tale signs on the ceramic tip of the plug.

    Realistically.. it is probably just as easy to find a Dyno and have them check the Air Fuel ratio.... far safer and if it is a constant speed rolling road dyno they can check at several throttle openings to ensure smooth operation across the rev range.

    Or... you can continue to fiddle around and get it running smooth and clean across the rev range and leave it at that...
     
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    Andych, Nov 3, 2020
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  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    @Andych - has nailed the description, I was suggesting 2nd or 3rd gear at least because to do a proper plug chop in top gear is getting pretty quick in the eyes of the law.

    You could do it as an inspection only process on one plug and see if it's close to totally white or a darker tan than it should be as a clue - there might not be a problem at all.

    Realistically, it's a tuning technique for when you don't have access to a dyno
     
    ruckusman, Nov 3, 2020
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  6. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Go on.. use the term... "Old School" lol I dont mind being labeled as such.
    First time I ever saw it being done was when in the first year of my Apprenticeship we were allowed to watch a full power run up in a fixed engine stand of a V12 Merlin.... holy cow was that a big impression on a 17 year old with an SL125.
    We had the honour of destroying one of the 24 spark plugs from this beast of an engine running on 110 Octane Aviation fuel.. ahhh the memories...lol
     
    Andych, Nov 3, 2020
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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Old Skool is magnificent because it's knowledge which allowed people to do this stuff before gadgets
     
    ruckusman, Nov 3, 2020
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  8. jmw76

    jmw76 Well-Known Member

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    Yep.
    Went to the pub yesterday.
    Had to check in with QR code app on my phone.
    Could not order a drink from the bar. Had to use the QR code thing again to order on my phone, then they bring it to you.
    And yes, meals had to be ordered from the menu accessed via the QR code on my phone.
    I doubt that it was any quicker or more efficient. Just puts another organisation in the loop to take a click on transaction as it goes from your credit card through the bank to app provider back to the pub.
    Where the hell is the world going?
    What ever happened to go old service?
    We kept having a young guy come to our table appologising for not being able to serve us directly and asking us how we were. If only he took our order.
    I must be getting too old.
     
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    jmw76, Nov 3, 2020
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  9. Brandon Otte

    Brandon Otte Well-Known Member

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    Yeah I appreciate all the ideas! I won't be doing the chop though, I tried a top speed run on a closed road which I frequent and seems about right so I think I'm just used to the lil 250s power and might...
     
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    Brandon Otte, Nov 18, 2020
    #29
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