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Project A work in progress my FZR 250 2kr

Discussion in 'Your 250cc Projects' started by downunderfzr, Feb 10, 2017.

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  1. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Sound's like the pilot jet's or pilot circuit's still might be a bit clogged ?
     
    my67xr, Mar 31, 2017
    #41
  2. downunderfzr

    downunderfzr Active Member

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    I bench synced them, soaked the jets etc in carb cleaner then blew them out with an air compressor. The bodies I soaked then gave them a bath in an ultra sonic cleaner for 1 hr. It seemed to me that air was flowing well though everything when i blew them out with compressed air.
     
    downunderfzr, Mar 31, 2017
    #42
  3. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Not starting cold could be blockages in the choke circuts or air leaks.
     
    Murdo, Mar 31, 2017
    #43
  4. downunderfzr

    downunderfzr Active Member

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    I think I may have found part of the problem - I decided to try a air leak test via some air pressure into the carb rubber boot via the sync test point & soapy water. Bingo i found a crack leaking in the rubber near on of the mounting bolts!
     
    downunderfzr, Mar 31, 2017
    #44
  5. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    If you take the carby's and manifold's off, clean up the manifold's and smear some Urethane over them, it cure's overnight and has a high chemical/heat resistance
    It's Sikaflex 227, $19 for a cartridge or $17.50 for a small tube at Bunning's
    https://www.bunnings.com.au/search/products?q=sikaflex-227
     
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    my67xr, Mar 31, 2017
    #45
  6. risky

    risky risky

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    also good for gluing boot soles on.
     
    • Informative Informative x 1
    risky, Apr 1, 2017
    #46
  7. downunderfzr

    downunderfzr Active Member

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    Finally i found time to work on the carbies again - so i pulled them apart cleaned & checked everything.
    Plus i repaired one of the rubber/ metal carb manifolds which was leaking (I'm having trouble trying to source a replacement).
    Unfortunately she still is running the same.
    I have noticed that I'm getting a fair amount of what sounds like noisy tappets when the engine is cold which reduces a bit once warm (the valves are now in spec). Plus grey smoke when i start her up after she been sitting for a fee hours which goes away once warm.
    To me it still sounds like like a fuel issue but I think a rebuild is going to be needed.
     
    downunderfzr, Apr 11, 2017
    #47
  8. downunderfzr

    downunderfzr Active Member

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    Here's a video at this stage the engine has warmed so the smoke isnt too bad but the knocking sound & bogging down around 10 000 rpm are there.
     
    downunderfzr, Apr 11, 2017
    #48
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Sounds like it needs some serious work. If it is a keeper, I would look for another engine to swap out and you could rebuild that one at your own pace.
     
    maelstrom, Apr 11, 2017
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  10. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Has it had a decent oil change lately and does it have the correct amount?

    Those intake boots are unobtainable .... u are better off just trying to reseal them as mentioned above

    intake rubbers.jpg

    Smoke after sitting for a period will be valve stem seals

    http://www.ebay.com.au/itm/10-x-Sea...919712?hash=item1a265f26a0:g:hyIAAOSwCGVX8R8N

    Check and reset the cam chain tensioner

    https://www.2fiftycc.com/index.php?threads/fzr250-cam-chain-tensioner.3336/

    Does it have EXUP?

    https://www.2fiftycc.com/index.php?...-powervalve-information-and-maintenance.1099/
     
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    GreyImport, Apr 11, 2017
    #50
  11. downunderfzr

    downunderfzr Active Member

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    Thanks.
    The oil has been changed & level is correct, i will check the chain tensioner.
    I reconnected the exup as it been wired open & is now working as it should. Bummer about the intake boots as it was cracked though the cast alloy/rubber section.
    Thought the valve stem seals could be the smoke issue, I have purchased a set of rings + head gasket so over the next few months I will pull the engine apart to do some investigation.
     
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    downunderfzr, Apr 11, 2017
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  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Guys looking at the cracked boots, that Sikaflex 227 looks awesome, now if you go to an industrial electrical wholesaler there will be really large heat shrink available. There is even some glue lines heatshrink available, it's damned expensive though.

    So my proposed course of action is a good smear of that sikaflex to fill the cracks and then put some heatshrink over it and heat it - that should pretty much keep the polyurethane right in place...

    Thoughts?
     
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    ruckusman, Apr 11, 2017
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  13. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    The cured urethane won't go anywhere, you need to cut, grind or sand it to get it off.
    Just scuff the rubber manifold with some 80 grit dry sandpaper first

    The 3LN manifold's dont have an extended alloy flange inside them, so you cant really get the heatshink near the flange to help seal it either.
     
    my67xr, Apr 11, 2017
    #53
  14. downunderfzr

    downunderfzr Active Member

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    Had some time to pull the motor apart today - found piston 1 had lots of play in the connecting rod bearing so removed it & found this. To me the bearing looks like its made of different material if you compare it the other con rod bearings.

    Now I just need to work out a list of parts to order.
    I borrowed a micrometer but wasn't much use as it only went out to 25mm so using digital verniers the diameter of the crankshaft where it connects to the con rod all com in at approx 26.96mm. So do i need to order standard size con rod bearings?


    IMG_20170422_151809007.jpg
     
    downunderfzr, Apr 22, 2017
    #54
  15. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    That's a spun bearing, pretty nasty too.

    One of my 3LN6's did a rod bearing - some genius installed a rod backwards

    C81JmrB.jpg

    My R6 also did a rod

    RNRjImE.jpg

    How is the journal on the crank if you run a fingernail across it? Check against the other rod journals. Have the crank measured and see if the journal can be linished to an undersize bearing. Check against the service manual.

    Unfortunately the rods are usually toast when the bearing spins, so you'll need another. The easier option is to find a motor with a working bottom end and use it. I transplanted a good 3LN1 crank & rods into my 3LN6 (with new chinese bearings for the crank - I left the rods alone. I wanted the frame and engine number to match, plus the 3LN1's have different engine mount points to the later models). It ran fine and rode like a new bike especially with the new clutch.
     
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    Linkin, Apr 22, 2017
    #55
  16. downunderfzr

    downunderfzr Active Member

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    Cheers linkin for the info I will have the crank checked & see if i can go down the oversized bearing route but getting hold of a good connecting rod might be the problem.
     
    downunderfzr, Apr 22, 2017
    #56
  17. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    You can have the rod 'closed and honed' at most engine machine shop for a reasonable price if you cannot get another.
     
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    Murdo, Apr 23, 2017
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