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Project FZR250 project

Discussion in 'Your 250cc Projects' started by neoncrypnid, Mar 1, 2020.

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  1. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Only if there is fuel in the bowl, have you checked that that?
    I know, sounds obvious but worth checking


    Sent from my iPhone using Tapatalk Pro
     
    Andych, Jul 11, 2020
    #161
  2. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    Yep made that mistake before haha. Its got fuel in the bowl
     
    neoncrypnid, Jul 11, 2020
    #162
  3. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    I would be removing all the jets in that carb and the pilot screw etc and getting some serious compressed air thru everything
     
    GreyImport, Jul 11, 2020
    #163
  4. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    I mean it can't hurt to try right? Ill give that a go and maybe get it to an ultrasonic cleaner soon
     
    neoncrypnid, Jul 11, 2020
    #164
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Compression test please.
     
    • Agree Agree x 1
    maelstrom, Jul 11, 2020
    #165
  6. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    Rekon the valves might be a bit funky?
     
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    neoncrypnid, Jul 11, 2020
    #166
  7. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    If anyone remember back that far, i did tighten the cams down at the wrong position because I got the TDC marks wrong on the flywheel. Im thinking now that I could have stuffed some valves up? Anyone know how to tell if the valves are dead without taking the head off? I do have a compression tester but it was a cheapie and doesn't work well on small engines at all but I'll give it a try too
     
    neoncrypnid, Jul 11, 2020
    #167
  8. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    If you've recently done the clearances then a significantly incorrect reading will tell you that something is up, if they're bent then they will have a much larger clearance than appropriate
     
    ruckusman, Jul 11, 2020
    #168
  9. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    Too easy. Guess I'll have something to do tomorrow
     
    neoncrypnid, Jul 11, 2020
    #169
  10. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    Valve clearances are actually unusually small, not large on that cylinder. I'm gunna drop the motor and just check the rest then, cos i hate working with such little space especially if I need to reshim anyway
     
    neoncrypnid, Jul 12, 2020
    #170
  11. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    I suggest checking compression first
     
    maelstrom, Jul 12, 2020
    #171
  12. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    Tried checking the compression with my tester but like i expected results weren't that useable. Got 34psi on cylinder 1, which ran well and 38psi on 4. I didn't bother with the other 2 and ill try and borrow a better one later in the week
     
    neoncrypnid, Jul 12, 2020
    #172
  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Slides propped open and the throttle butterflies open 100% - those readings are very low for both 1 & 4 so by rights it shouldn't be running at all
     
    ruckusman, Jul 12, 2020
    #173
  14. jmw76

    jmw76 Well-Known Member

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    Hmmm. Those numbers are way too low if they are real.
     
    jmw76, Jul 12, 2020
    #174
  15. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    I know they are crazy low. I didnt have the throttles open though, I'll redo the tests like that. Ive gotten similar readings from other small displacement engines so I'm erring towards the tester being the problem
     
    neoncrypnid, Jul 12, 2020
    #175
  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Without the throttle plate butterfly and slides propped open I'd say that tester is an unknown, but wouldn't say it's a problem til a re-test has been conducted with unobstructed air flow into the cylinders
     
    ruckusman, Jul 12, 2020
    #176
  17. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Even better is to remove the carbies... then do your Compression test. Make sure you have a battery booster or a car battery hooked up to ensure max cranking speed. Keep winding on the starter until the gauge stops rising.. Test each one dry and then with a small squirt of oil, this will show up any potential issues with Rings.
    Always make sure you write down each reading.. memory plays tricks on your even in that short a time..
     
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    Andych, Jul 13, 2020
    #177
  18. neoncrypnid

    neoncrypnid Well-Known Member Premium Member

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    I think i know why this tester is crap. The schrader valve is in the actual gauge rather than at the engine, so the combustion chamber size is effectively increased by whatever the volume of the hose is. Anyone know if its possible to get an adapter with a valve in it? Another good reason to not waste money on dirt cheap tools
     
    neoncrypnid, Jul 13, 2020
    #178
  19. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Unless you are going to spend a lot of money on a kit you will not use much you are probably going to have to live with what you have.
    You might get lucky and find a tester with no hose but it will most likely have a tapered rubber tip that you need to hold down on the plug hole while you crank the engine over.. still has its limitations...
    The thing is that air compresses.. so if you spin the engine fast enough and for a long enough time on each cylinder you will see the pressure continue to rise on the gauge. The pressure itself is less important than the differences between each cylinder. If you are going to use it... make sure you spin the engine for as close to the same time on each test.. that way you are getting a comparison.
    The only other factor is if the hose is expanding... Not much you can do about that but really the hose should be good for the pressure you are trying to pump up. The other option is to forget about a compression test and get yourself a leakdown tester.. this will tell you more about what is happening in the engine than a compression test will anyway.
     
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    Andych, Jul 14, 2020
    #179
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I don't know what your tester looks like but are you able to insert a schrader valve yourself in the end of the adaptor- you can get brass fittings with them inside already from air conditioning and heating places which will have a thread on the outisde

    One other option is to use either a bike tyre tube fitting if it's adaptable or the same element from a tubeless tyre fitting modified appropriately

    Less $$ and perhaps an easy task - perhaps
     
    ruckusman, Jul 14, 2020
    #180
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