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Project FZR fix up

Discussion in 'Your 250cc Projects' started by Yetiburger, Oct 7, 2017.

  1. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    As above... but if they were with a cold engine it isnt too bad... hard to diagnose much just on a compression test.. You are better off trying a leak down test and that will tell you if it is rings, head gasket or valves / valve seals.
     
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  2. Yetiburger

    Yetiburger Well-Known Member

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    Yes the carbs were removed. how does one perform a leak down test?
     
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  4. Yetiburger

    Yetiburger Well-Known Member

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    ok so I performed a leak down test (maybe).
    I had a lot of trouble using the leak down tester and I really don't trust the results as I couldn't seem to set the tester consistently.

    It did show that cylinder #2 has a leak around the exhaust valve and slight Crank Case (CC) blow by.

    The results from the leak down test were weird and contradictory to the compression test.

    #1 23% in the green on the tester, no obvious leaks
    #2 50% leaks out of the exhaust pipe and CC
    #3 45% only a very slight CC leak detectable
    #4 25% maybe a very slight CC leak

    Do these results make sense given the compression test?

    Does anyone have any tips on using a leak down tester?
     
  5. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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  6. Yetiburger

    Yetiburger Well-Known Member

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    ok guys can anyone confirm valve clearance?
    EX = 0.21 - 0.30 mm
    In = 0.11 - 0.20 mm

    And from the compression test and leak down test results is this motor stuffed?
    leak down test would zero but would not return to zero after the cylinder test.
     
  7. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Clearance's are correct
     
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Stuffed? Having to fit new rings to a 30 year old motorcycle does not really qualify as stuffed. I would call that a service. :)
     
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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Those tests conflict, the best performance on the leakdown was the worst on compression

    You could try some threebond engine conditioner down the plug holes and past the valves to remove carbon, you would obviously need to drain the oil afterwards.

    Watched the video you posted of it running way back near the beginning of the thread, it was doing superbly given that it was running without the airbox.

    I think it may need a good run more than anything, you've been through the carbs, coil replaced, plugs were a problem for you at one stage - if you have one cylinder not firing consistently, the carb to cylinder head boots could be loose and leaking air, if you've removed them at any stage, another forum user was spinning in circles with a lot of what you've been through, turned out to be that, or they could be cracked

    I say get on it and ride it, get the idle circuit tuning done with the engine up to temp
     
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    When you did the leakdown test how did you determine TDC compression on each cylinder and how did you hold it there?
     
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  11. Yetiburger

    Yetiburger Well-Known Member

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    I determined TDC with an Allen key down the plug hole. the motor didn't turn over under the test that I saw. I really don't trust the leak down test but it did give me an indication that there may be a leak pass one of my exhaust valves and some ring blow by, but the blow by didn't sound major. I will check my valve clearances again to make sure they are within spec. Then i'll give the carbs another clean out and check over as well as the boots and see if I can get it to go.
    It just didn't really run again after that video at least not very well. was always hard to start or not running on 4 cylinders.
     
  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Probably not necessary to go to the lengths of cleaning the carbs back out again, check the fuel level with them on the bike first - that's the important one which might take some fiddling.

    I think people recommend spraying start-ya-bastard or carb cleaner or brake cleaner on the boots to check for leaks with the engine running and if it climbs you have a leak.

    If you do need to adjust the float levels to attain the correct fuel level, then worth checking that you have smaller main jets on the inside, depending on what series carbs they are 3LN1 or 3LN3 and the kits that you used as to what those actual jets will be. It won't rev out properly with them reversed, and that error has been noted in the supplied kits from keyster, the inner and out main jets were in the incorrect boxes.

    I seem to recall you got a set of 3LN1 carbs as replacements, so float height is 16mm, which should yield a 9.2mm fuel level - if that float height doesn't yield a 9.2mm fuel level, then whatever the adjustment needs to be, lowering or raising the fuel level, that amount is added or subtracted from the float height measurement.

    The float height measurement PLUS the fuel level height should sum to 25.2mm or thereabouts, so as one increases, the other decreases by very close to the same amount, which takes the guess work out of it and having to make an adjustment, reassemble, refit and refill to check the fuel level - only thing to remember is that the fuel level is the important measurement and the one to get correct

    Last thing is the emulsion tube needles:
    1st possibile setting - If they are OEM and all 5CT7 across all 4, centre clip on all 4 AND the centre two have the 0.5mm shim underneath
    2nd possibile setting - If they are OEM and 5CT7 and 5CT9, then 5CT7 go on the outer two and 5CT9 on the inner two.
    If you have used the keyster needles as replacements, then they are all 5CT7 then it's the first possible setting
     
  13. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Just wondering why you wouldn't use the Timing marks and valve positions to determine TDC compression?
    At the end of the day you may well be chasing your tail looking for potential faults that are just not there... sure, it may need to have a hone and new rings... most bikes of that age will but generally speaking they will start and run. Most starting and running issues on FZR's appear (to me at least) be associated with carby's and their poor maintenance / or lack of same.
    Many much smarter people in here than me have spent countless hours on FZR carby's and been frustrated along the way.

    Electrical gremlins can also pop up but generally speaking if you have compression, fuel and spark (in the right combinations) it should run...

    Concentrate on getting it running first and when it runs and is ridable worry about a potential re-build.
     
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  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Just to be clear, for anyone reading this thread, it is TDC compression that has to be used not TDC. Also, to the best of my knowledge, timing marks on 4 cylinder bikes usually only show TDC for cylinders 1&4, but you could just put a mark on the opposite side of the flywheel for 2&3 as they are 180 degrees apart.
     
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  15. Yetiburger

    Yetiburger Well-Known Member

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    Yeah thanks guys. I think its just the long term frustration. I have the cam cover off now so I will double check clearances for peace of mind. was just frustrating that at one point it ran and I even rode it around the block but then it wouldn't start or run properly with no real change to anything.
    I will check the jet and needle settings, but I recall double checking these when I put them together as the 3ln1 carbs were different.
     
  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Fizzers can dispense frustration by the bucket load till you find the cause, however being frustrated as we all know isn't ultimately helpful

    There's been errors with main and pilot jets swapped, which is easy to do actually as they're the same type

    Just go through your list, easy stuff first - fuel level, then check and adjust carb floats if necessary.
    Spark, correct leads to correct cylinders - that's an easy mistake to make, and one out of left field but it has been done, has it run since you did the valve adjustments?
    The inlet and exhaust cams can be swapped, won't run, but there won't be physical damage.
    IN and EX is in the casting between cylinder 1 & 2, if you're checking the valve clearances, have a peak for that at the same time
     
  17. Yetiburger

    Yetiburger Well-Known Member

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    ok all valve clearances are within spec and cams in correct orientation.
    for the leads just confirming its a wasted spark setup? one coil to 1 and 4 and the other coil to 2 and 3?
     
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  18. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Yeah coil's are for 1&4, 2&3
    Are your fuel level's good ?
     
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  19. Yetiburger

    Yetiburger Well-Known Member

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    will try get the carbs back on by end of the week.
     
  20. Yetiburger

    Yetiburger Well-Known Member

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    ok so I checked the carbs over.
    All jet are in the correct place and the needles on the correct settings.
    Blew it out with the compressor and put it all together and it now seems to start every time on full choke.
    won't take throttle or run without the choke.
    I have set the mixture screws to the recommended 2 turns out as a base.
    I have not yet checked fuel levels. I will attempt to do this over the weekend.
    but here is video of it is his current state.





    so I guess its just a matter of struggling through the tuning from here.
    Hopefully with all the information provided especially from @my67xr I can get it sorted.
     
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