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Help FZR250 - Think I've dropped a cylinder

Discussion in 'Yamaha 250cc In-Line 4's' started by Amara, May 28, 2019.

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  1. Amara

    Amara Active Member

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    Not too sure how well it comes across on camera, but the throttle response went out the window, and it sounds like it's dropped a cylinder. Sounds similar to a ninja 300 when I venture past 6,000 rpm

     
    Amara, May 28, 2019
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  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Let the bike cool down, then start it up and touch each exhaust pipe up near the head, see if they're all the same temperature
    Don't leave it running too long otherwise you'll burn yourself

    Could be spark plug's, coil's, coil lead's or spark plug cap's causing a missfire
     
    my67xr, May 28, 2019
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  3. Amara

    Amara Active Member

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    I'm going let it warm up then spray water on the headers to see which ones aren't firing. So far I've been told to change the spark plugs, so I'm going to replace all 4 plugs too
     
    Amara, May 28, 2019
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  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Has it been sitting for long?
     
    Linkin, May 28, 2019
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  5. Amara

    Amara Active Member

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    Not really, maybe a week at the most, I was talking it easy yesterday because of the wind, although I had to slow down for a sharp corner, and I pushed 2nd gear to about 16k coming off a bridge coming out of said corner, then shifted back up to 5th
     
    Amara, May 28, 2019
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  6. Amara

    Amara Active Member

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    Looks like I've lost cylinder 4 :(


     
    Amara, May 28, 2019
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  7. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    GreyImport, May 28, 2019
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  8. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    FZR Tripple
     
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    my67xr, May 28, 2019
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  9. Amara

    Amara Active Member

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    So I'm only running 186.75cc i3 instead of 249cc i4. No wonder I'm significantly down on power
     
    Amara, May 28, 2019
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Spark, compression & fuel. Those are the three things you need. Once you have thoroughly tested all three we can make some suggestions if that is the purpose of your post.
    Cheers
    Blair
     
    maelstrom, May 28, 2019
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  11. Amara

    Amara Active Member

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    I've replaced the spark plug in cylinder 4 to start with, and that fixed the issue for a short amount of time. I've run out of day light, so I'll try to put the rest in tomorrow
     
    Amara, May 29, 2019
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  12. jmw76

    jmw76 Well-Known Member

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    Suspect your are fouling up your plugs for some reason. If the mixture is way out, it will foul new plugs in absolutely no time.
    No amount of cleaning seems to be able to bring them back.
    Measure the resitance of the plug with a multimeter (between centre electrode connection and the body). Any value less than about 50M ohm and the plug is cactus.
     
    jmw76, May 29, 2019
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  13. Amara

    Amara Active Member

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    I went for a quick test ride up town to check the mail (about 1.5km) after I replaced the spark plug for cylinder 4. Cylinder 4 was firing on and off on the way to the post office, but worked fine on the way back home until I started to slow down to enter my driveway, then I could hear that cylinder 4 had stopped firing again after I'd entered the driveway
     
    Amara, May 29, 2019
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  14. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Check the plug hasn't been fouled.
     
    Linkin, May 29, 2019
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  15. Amara

    Amara Active Member

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    I tried taking a couple mm off the end of the spark plug leads, let the bike warm up, then went to ride the bike. Problem is still there. My bike idles ok after I changed the plugs and cut a couple mm off the spark plug leads, but when I go to take off, #4 drops in and out still. I can't do much else without removing the engine from my bike, something I really don't want to do. I'm taking it to the mechanic on Monday. My bike has compression and spark, but I don't have the tools or the time to get the AFR sorted.
     
    Amara, May 31, 2019
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  16. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    I'd be doing a leakdown test on #4 to see if there is any leakage, and how much if so.

    If the other cyls are all OK, spark/fuel is all ok then I would consider valve clearances the next step.
     
    Linkin, May 31, 2019
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  17. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I had problem's with my FZR at one stage, the exhaust temp would be good, then it'd run cooler, then sometime's come good again for a bit.
    I pulled the mixture screw out that carby and found a tiny piece of rubber sitting above the port through to the carby bore.
    The new Keyster o'ring must have had a dag hanging off it when i fitted it, and i missed it.
    I took the bit of rubber out and it was all good from then on.

    [​IMG]
     
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    my67xr, May 31, 2019
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  18. Amara

    Amara Active Member

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    Taking my bike to the mechanic to get fixed next week
     
    Amara, Jun 4, 2019
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  19. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Have you had a rough quote?
    It could get expensive if you need the valve clearance's done and carby's rekitted
     
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    my67xr, Jun 4, 2019
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  20. Amara

    Amara Active Member

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    They didn't give me a price, but they are going to let me pay off $100 or so a week. I told them my bike needs the carby balanced and tuned, new plugs, and the ignition barrel needs to be secured.

    My last bike (2008 Hyosung GT250R) had mud blocking the main jets in the carbs. They flushed out the fuel tank, cleaned, balanced and tuned the carbs for $360 ish and I had no problems after that.
     
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    Amara, Jun 4, 2019
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