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ZXR-250 A1 Stalls ;(

Discussion in 'Kawasaki 250cc In-line 4's' started by F1dz, Nov 5, 2013.

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  1. F1dz

    F1dz Member

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    Well after riding to work and around to Kers' place, she goes well, had a few people telling me that my piston rings could be buggered coz of the fuel being let thru them? Is that a thing? I would have thought that piston rings were there to seperate the fuel vapor and the oil, not to specifically stop the fuel liquid?

    Getting a new fuel tap as well from silverwater wreckers!!!

    Hopefully problem solved and i can start work on the old mans BMW r69s!!!
     
    F1dz, Nov 8, 2013
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  2. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    If you get fuel flow into the cylinders and the rings are not too good then yea that can cause the fuel to flow through (slowly).

    But once you start looking into engine problems like that it's a whole different ball game. Have you done a compression test?? It will give you a good indication if there is anything wrong with the cylinders themselves.
     
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    DougFella, Nov 8, 2013
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  3. risky

    risky risky

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    rings hold out against the bore with compression behind them. to do a compression test remove all spark plugs , do the test on 1 cylinder at a time and write down dry compression. if 20 percent variation there is a problem.then squirt oil into each cylinder and note compression again. all should rise equally due to the oil sealing the bore.if not either poor rings or more likely poor valve seal.try and get comp tester that screws in and try to have motor turn equally on each cylinder.petrol will always flow to sump through rings.
     
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    risky, Nov 8, 2013
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  4. F1dz

    F1dz Member

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    Nah i dont have a compression tester, there are some things that I have no trouble tackling, but when it comes to engine specifics and the like Im quite apprehensive. Though sooner or later is if want to do all my own work then im going to have to work it out.
    Risky thats what i was thinking the whole time, even if there is supposed to be a seal around the rings, even a small hole will let fuel through and that happening over a week or so will lead to a bit of fuel in your sump right?
    But after all that she runs well and we havnt hit any walls yet!
    Glad to have you guys to run things by, my noobness is slowly getting smothered in grease, oil and fuel!
     
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    F1dz, Nov 11, 2013
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  5. risky

    risky risky

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    in regard to rings....a motor normally has 3 rings, 2 compression and an oil scraper which is 2 rings in one. all rings have some squeeze and put static pressure on the wall of the bore.the rings have end movement and the end gap is calculated on bore size to allow for expansion.the end gap could be as small as the thickness of a hair. fluid will leak past slowly ifit soaks in. when the motor is running the gas pressure gets behind the rings and holds them out against the bore.not a perfect seal but as close as you can get.if the rings or bore wears then the end gap opens up and the rings lose there tension lessenning the sealing affect.petrol fumes can get into the sump and oil can pump up the bore.if the motor is running rings are the last item to replace as being so small they are delicate.
     
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    risky, Nov 11, 2013
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  6. F1dz

    F1dz Member

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    So a cylinder thats full to the brim with fuel, for arguements sake, no matter if it was worn or brand new will always let some, even a tiny bit, of fuel through?
    I was having this discussion with Kers on friday, he was telling me that because the fuel was getting through the rings were buggered...but the rings were never designed to hold back liquid fuel.
    I suppose it cant hurt to get a compression tester, how do you test it? not with motor running im guessing, just turn the rear wheel?
     
    F1dz, Nov 11, 2013
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  7. risky

    risky risky

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    rings cannot hold back liquid fuel forever. compression tester....remove plugs and take power off coil. put tester on each cylinder and turn with starter motor. record each cylinders compression and see if within specs.
     
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    risky, Nov 11, 2013
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  8. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    GreyImport, Nov 11, 2013
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  9. risky

    risky risky

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    if you buy a compression tester do not get a stubby as it may not reach the plug hole. go for one with a longer shaft and preferably will screw into plug hole though the rubber cone will do. push hard.
     
    risky, Nov 11, 2013
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  10. cal

    cal Well-Known Member Premium Member

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    interesting, i recall seeing some minor fuel contamination in my sump when i last dropped the oil, but... this was when the bike was running super rich...
     
    cal, Nov 11, 2013
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  11. F1dz

    F1dz Member

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    Yeah it may well have been from a leaky petcock... Also, my petcock leaks very slightly, less than one drip a sec, i bought a 2nd hand one from silverwater motorcycle wreckers and it leaks as well. My question is; if there is no vacuum will the fuel stop? As in if there is a seal and the bike is off will the fuel shut off in RES?
    Becuase both of my petcocks leak slightly when disconnected from the fuel lines...
     
    F1dz, Nov 12, 2013
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  12. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    I actually had a slight leak out of my one the other day and it's brand new so I'm curious if this is possible now too, perhaps it was gravity and a siphon in the hose that was holding the small diaphragm open. However I was under the understanding that on RES or ON there should be no duel flow when there is no vacuum.
     
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    DougFella, Nov 12, 2013
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  13. F1dz

    F1dz Member

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    Thats exactly what i was thinking, but unless there is a solid explination as too why 3 fuel petcocks, one brand new, one second hand and one rebuilt all leak slightly then i would assume all of them are fooked... :(
     
    F1dz, Nov 13, 2013
    #33
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