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New Member G'day Guys! New member with FZX250 Zeal '98

Discussion in 'New Members Say Gday' started by Ben Jammin’, Jan 9, 2018.

  1. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Yeah my spacer's are 130mm long and the progressive spring's are 400mm long.
    There is 65mm of spacer hanging out the top of the fork when i removed the top cap
    20180117_154853.jpg
     
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  2. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Have you had the mixture screw's out when you blew the carby out ? If there's anything blocking the hole through to the main bore then it won't let any fuel through at idle
    This is what i found at the bottom of the mixture screw thread in my FZR, a chunk of rubber, it was enough to intermittantly block the idle feed port, the pipe temp on number 1 would change over 30 degree's and back when it was running
    [​IMG]
     
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  3. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    I didn’t take the mixture screws out.
    Someone once told me ‘never touch the mixture screws’!
    Maybe that’s the issue?
    Would that affect it at higher revs too? It seems like No.1 isn’t firing at all? Although when I rode it I felt like I had a misfire, but that could have been No.1 starting to fire occasionally?
    Could it be compression? Maybe with all the rust etc that was in the system, piston rings might be stuck on that cylinder?
    Am I overthinking it now? :prankster:
     
  4. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Simple thing's first,
    screw each mixture screw in till it's just firm and while doing it count the amount of full turn's in, eg 3 turn's in on number 1 carb, 2.75 turn's in for carb 2 etc etc
    Then set them all back to where they were.

    Once you've written them down take the number 1 mixture screw out (including the spring, washer, and o'ring) and spray some carby cleaner in through that hole it may help clear any blockage.
    Refit the spring washer and o'ring to the mixture screw and set it at where it previously was and try starting it again
    Then feel the number one pipe again
     
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  5. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    The starting point for the mixture screws on the Zeals is 1.75 turns out. Caught me out when I did my carbs as it ran rich/low power on the dyno and chewed fuel, couldn't figure out why (though it had 3LN headers without the exup and an open pipe)...
     
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  6. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    Yes, good point, keep it simple! :oops:
    I'll make a note of how many turns out from closed on each screw, and then remove and clean.

    Incidentally I got a call from the garage to say they'd love to give my bike a pass, but it's only running on 3!
    I didn't realise they needed to start it to check the lights, brakes etc....!
    Oh well, lesson learned.
    I'll collect it tomorrow arvo and let you know how I go.

    Thanks again for the info @my67xr
     
  7. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    Cheers @Linkin
    I do remember reading somewhere that they should start around 1.75, maybe it was on another thread in this forum?
    Can't remember, I've slept since then....! :confused:
     
  8. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    6B36ABAF-9A8C-4AE1-A5A3-26CFF9FBAA90.jpeg 846C67D2-A8DC-41B3-AB16-2AC46C5E6D13.jpeg AEF592D6-5E03-467F-B76F-4165326381AB.jpeg So I got the bike back from the garage today. The guy said he stuck a pressure tester in and found No.1 cylinder had only 50psi, whereas No.4 cylinder had 115psi !!!
    He suggested to buy some Subaru upper engine cleaner and pump that through in case something was sticking a bit and causing the low compression.
    I did and it seemed to blow out lots of smoke and started warming up No.1 header pipe. But still not hot.

    I took out No.1 mixture screw and sprayed some carbie cleaner in the hole as suggested.
    It looked clear, but I did it anyway.
    I seem to be getting a hot header now but notably, not as hot as the others.
    Incidentally, there didn’t seem to be a washer or O’ring???

    The idle is really erratic too. After running the engine for a while I set the idle at the suggested 1600rpm.
    But all of a sudden the thing jumped to around 4000rpm without me touching anything.....
    When I rev it, it’s pretty responsive but it seems to take a few seconds to drop back to idle.

    Not fully sure what to try next?

    At least the garage didn’t fail me on my inspection. He just told me to get it running smoothly on all 4 and bring it back.
    Also, whilst we’re on the plus side, the forks are performing well, as is the front brake following it’s thorough cleaning. :thumb_ups:
    Thanks for all the support thus far guys.
    I feel sure I’m not far away from nailing this thing!

    Any ideas where I should look next?
     
  9. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    OK, so you have low compression on that cylinder. The next step is a leakdown test to narrow down the cause. It could be the rings, but it is unlikely as the other cylinders are good. That leaves valves and the valve guides. This engine uses cams with shim-under-bucket setup, so valve guide wear shouldn't be a huge issue like it can be with pushrod/rocker engines (see massive archaic design yank V8's)

    It would also pay to check the valve clearances. The spec is 0.11-0.21mm for the inlets and 0.21-0.30 for the exhausts. Over time, the valve seats wear down and the clearance reduces. While you are in there you can check the condition of the cam chain.

    That pilot screw should have a metal washer with a chamfered edge and an o-ring.

    PilotScrewAssy.jpg
     
  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    http://www.litetek.co/Guide_PilotScrew.html
    PilotScrewAssy.png
    It will never run correctly without the o-ring and washer. The compression sounds like an issue and a leakdown test would be a good idea. Valve clearance will also need doing
     
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  11. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Oh too funny, @Linkin posted the same thing.
     
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  12. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Great minds think alike :prankster:
     
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  13. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    Thanks for the info @Linkin and @maelstrom.
    Looking back at my picture of the mixture screw hole, it looks like maybe the washer and o ring didn’t come out with the screw?
    I’ll check again tomorrow.

    So anyway, when I first got the bike, the previous owner says that following his third carbie clean up at the garage, the machine didn’t seem to have as much power as it should.
    After I cleaned the carbies and still found No.1 not firing, I put it down to the rust and crap in the float bowls that kept coming though.
    After cleaning the jets for about the third or fourth time, and some serious head scratching, I found that the mixture screw on No.1 carb was wound fully in! I opened it to match the others and got a warm header so thought I’d cracked it finally. (I only just remembered that bit!)
    The bike then stood for about 3 years before I decided to derust and seal the tank etc, which is where this thread started.

    Question: if the previous owner ran the bike, for let’s say 1000km with No.1 mixture screw closed, what would that do to No.1 cylinder/carb/piston/valves etc?
    Could that be the cause of a low compresssion?

    I’m with you @Linkin, I don’t think the rings are worn as the bike has only seen 10k. It was stood outside in the elements when I acquired it for maybe a couple of years, and it’s been stood in my garage since then for another 4yrs approx. My hunch is that something is stuck/corroded like a valve not seating properly.
    But as someone’s clearly been ‘at it’ before I took over, I can’t rule anything out.
    I really hoped I’d get it running without a top end strip down, but maybe this No.1 firing issue was already there a long time ago???
    Who knows?
    But we’re sure to find out.... :headbang:
     
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  14. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    So, here’s a vid of the bike overrun issue:

    Any ideas why the revs don’t drop quickly?
    All mixture screws are set at 1.75 turns out, as per the specs.
    There’s no hesitation whatsoever when I rev it. The throttle cables are free moving.
    Is this a fuel height, in the float chamber problem? (Cos I haven’t checked that yet!) :idk:
     
  15. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    My best guess is that it is running lean. Try winding the mixture screws out to 2 turns or 2.25 turns and see if it improves. The baseline setting is only a starting point
     
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  16. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    Thanks @Linkin I’ll ll give that a try.
     
  17. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    I think I’ve found the cause of the low compression on cylinder 1: 73C4DF18-FDF7-4F96-801A-1D368AA8E3EB.jpeg

    This is what all the other inlet valves look like on 2,3&4:
    F1C702B9-98FB-4858-9A3E-B88D332ABE72.jpeg

    The back of the butterflies on the carbie give it away too:
    1A3DE9AB-8B46-4007-9D41-BB624240997A.jpeg 19AEED49-1C07-4CFF-9B91-DC297BFA6121.jpeg

    I checked the amount of fuel that came out of each float chamber and apart from the fact my 7yr old daughter thought it looked like a cool experiment and marked the lines for me, I think they’re all ‘roughly the same! ;)
    991A8411-3857-4935-A93C-CFCBD7E4B3C9.jpeg

    I’ll proceed to try and degunk the inlet valves in cylinder 1 and update!:thumb_ups:
     
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  18. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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  19. Ben Jammin’

    Ben Jammin’ Member Premium Member Contributing Member

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    So I used a load more of the Subaru upper engine cleaner and got a rag on a rod to wipe out as much goo as I could reach.
    @GreyImport I guess it’s a similar thing to threebond? Applies in much the same way.
    The result looks much better and the valve seats are visible again! :thumb_ups:
    574E327B-BC05-4761-91C6-E43ECAB33054.jpeg

    I started the bike up with choke and the good news is that I burned my hand on the header! ;)
    So looks like we’ve now got compression! :thumb_ups:
    Unfortunately, when I turned the choke off, the header cooled down again! :headbang:

    So I removed the mixture screw to blow some more carb cleaner in the hole, and the good news @my67xr, @Linkin and @maelstrom is that there was a washer and an o ring in the hole after all.
    The not so good news is, I dropped the washer and can’t find it! :prankster:


    Is there anything else in the carbie that could get blocked and cause the thing to stop sucking fuel through when it’s off choke?
    (The jets are clear.)

    So close, but oh so far! :lolsign:
     
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  20. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Not having that tiny washer there will make the spring dig into the o'ring and damage it.
    The washer's are also used in the little Mikuni copy's used on pitbike's for the mixture screw too.
    I lost the washer down the gap under the starter motor when i cleaned out that little bit of rubber from the mixture screw hole, and used one off an old pitbike carb.


    On the inlet /filter side of the carby there is a small port on the right side (looking at the carb's from the rear of the bike) that let's air go through to the pilot circuit, if this post has a blockage then it wont let much fuel through.

    You could try running the bike, give it a little rev, and put the palm of your hand over the top of the carby to stop air getting in
    Bike will probably stall, but it might be enough to suck through anything that's causing a restriction in the pilot circuit.
    The palm of you hand will get wet with fuel, and it'll be a touch harder to start again till it burn's the extra fuel, but it might help clear it?
     
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