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Help Valve Clearance Inspection

Discussion in 'Kawasaki 250cc In-line 4's' started by DanoHosko, Mar 29, 2020.

  1. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    I replaced all my vac lines & still ran ordinary. Eventually found the vac valve diaphram was cactus & sucking through to the airbox line. Disconnected & blanked off vac supply line to vac valve & vented carbs to airbox. Worked. Still can’t get my head around what vac valve does? (Sorry a bit off topic)


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  2. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Ah yeah i found the vac diaphragm on my fuel tap is pretty ropey so i ordered a new tap, cant seem to find replacement vac valve anywhere but shape looks similar to the tap diaphragm
    Might try and remove it too like you then if it seems suspect
     
  3. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    See how she goes...


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  4. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Ok, new cam chain is fitted
    The Pin looks like it peened nicely, hard to say if it damaged the link though as it looks a little funky around where the pin exited the last link (picture doesnt really capture it though

    _20200410_120015.JPG
     
  5. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    As long as the link moves freely it should be OK. If you are worried, use the peining tool again.
     
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  6. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    I think i owe you a beer or two for all the advice bud!
     
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  7. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Typically i've f***ed up the valve clearance measurements somehow...
    Seems some of them are out of spec too loose now by up to 0.03mm

    Is this a disaster and redo or just means I'll be down on power for a bit?
    Mostly worried about the poor idle issues to be honest
     
  8. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    Bugger...They are fiddly to get a good read on feeler guages. I had to get some real point ones to get into the space. Is your motor fully cooled down?


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  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    0.03mm (just over 0.001") is nothing to lose sleep over. It will be fine.
     
  10. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Yeah my feelers aren't great either they have increments of like 0.03mm so have to combine them to get different sizes
    Motors stone cold hasnt been run in 4 months i reckon


    Ah awesome thanks :D
     
  11. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    Yeah I used imperial guages & converted them. Imperial guages seem to go down smaller increments so it helps a bit. Now that it is running do you have any dramas starting it after it has been running around 20 minutes?


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  12. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Not running yet still, got an issue with the carbs, when i have them fully inserted into the intake funnel things the throttle is catching
    Seems like it might be the sync screws catching but can't work out why they would be all of a sudden

    Video below
    First couple goes the carbs arent pushed in fully, then i push it in and the throttle starts catching.
    Tried with the spare carbs, same problem, one of the videos looks like the syncs screws are catching the intake funnels
    Very odd





     
    Last edited: Apr 11, 2020
  13. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Bah what an idiot, if the clamps aren't tight then it catches
    All sorted :oops:
     
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  14. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    Nice...at least you found out why.


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  15. banner001

    banner001 Well-Known Member Premium Member Contributing Member

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    Hi everyone, I'm just checking, the 8mm shims from precisionshims.com.au these are definitely a replacement for the 7.9mm diameter shims currently in my 1990 zxr250? Cannot find a manufacturer in the UK so will use them. And lastly they have some interesting sizing, for example a 2.68 shim usually means 2.675, are these guys the same, and if so do their 2.65 and 2.66mm thick ones really only differ by 0.01mm or is the 2.66 more like 2.665?
     
  16. banner001

    banner001 Well-Known Member Premium Member Contributing Member

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    Also, someone mentioned is it possible to remove and fit link less camchains... Yes it is, you just need to shave off a few mm of the aluminium chain protector.

    [​IMG]

    Easier than splitting the cases, and I'm not a fan of purchasing a non OEM camchain, and as the OEM is link less then that's what I'm going for.
     
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  17. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Hey mate

    Mine were measuring around the 7.85mm mark, i i fitted the 8mm ones from precisionshims and they fitted in ok

    Somehow the new shims ended up making the valve clearances slightly higher than my calculations (not sure why)
    Could the shim holder bit be tapered? Unlikely i would say

    I measured all the shim recesses and they were around 8.02mm diameter, and the 8mm shims measured around 7.98mm diameter


    Sorry couldn't comment on the accuracy of the shim thickness, im guessing rounding to the nearest .01 is enough?
    I will say precision didnt have a couple of sizes so sent the closest size they had on the shelf instead
     
    Last edited: May 24, 2020
  18. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Ah yeah I seen someone had done this too haha
    I went for a split chain, didnt didnt wanna dremmel the casing myself
    Also if you somehow lost tension in the chain, by removing that bit of casing do you not risk the chain coming off the sprocket?
    Im guessing the casing was designed so tight for that reason?
     
  19. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Best to ask those questions of Precision shims... they are very good with quick responses and really helpful. Best bet is to measure and calculate... then double check... then check again.
    There is a copy of a sheet somewhere in the forum where you check each valve setting.. then measure the existing shims so they are all written down... heck, if you are any good with spreadsheets you could make it so the calculations are done for you for the correct size. Always shoot for close to maximum clearance... a little under is all you want and that gives you plenty of time for the clearances to close up.. as they will.
     
  20. jmw76

    jmw76 Well-Known Member

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    Note sure that is a mod I would do. I would expect the metal is there to prevent the chain jumping around the gear if it gets a bit slack. It could potentially jump a tooth or 2 and you would then be in diabolical problems. Granted, it is only likely to happen when the chain/tensioner is badly worn.
     
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