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Project Suzuki Across Engine Rebuild

Discussion in 'Your 250cc Projects' started by Jethalter, Mar 27, 2019.

  1. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Could be leaking needle and seat's, especially with the puddle of fuel under the bike.
    Definately swap the new one's in
     
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  2. Jethalter

    Jethalter Active Member Premium Member

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    So i pulled the carbs again, i tested the needles and seats blowing into the fuel in hose, no air coming out. So at a guess they are seating.
    The floats move freely throughout full travel range.
    I will change the needle and seats. Also will test all my floats again, see if one has a little pinhole or crack or such that it fills it up and holds it low slightly or something.

    But inspection shows there shouldn't be a problem but i still think there is.
     
  3. Jethalter

    Jethalter Active Member Premium Member

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    So tested the floats and needles and seats, couldn't fault any of it.

    Put the carbs back on, no air box, waited for fuel pump to prime, it did then shut off. Cranked for 10-15 secs, nothing. Put my hand over the carbs and bam started straight away.

    Ran for about 10-15 mins, waited 30 mins with engine off, press the start button, fired right up. No fuel leaks so far, so going to give it a few hours and recheck.
     
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  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Did you pull the needle and seat's out to check for any dirt or bit's of rubber inside the carby's ?
     
  5. Jethalter

    Jethalter Active Member Premium Member

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    everything in the carbs are clean as a whistle. took the jets out, needles, diaphragms etc...
     
  6. Cbuzz

    Cbuzz Well-Known Member Dirty Wheel Club

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    Ahh I see you checked already nevermi d.
     
  7. Jethalter

    Jethalter Active Member Premium Member

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    So after about 2 hours of sitting, tried starting it. same result, won't start without hand over carbs.
    Once i put my hand over the carb instant fire up.

    When it was warm, i played with the idle mixture screws, about 1-1.5 turns from seated it starts running rough, fully seated it drop to low rpms. About 6.5-7 turns out it starts running rough again. So i've set them at 3.5 turns, 3.5-4 turns from seated seems to be its sweet spot.

    Letting it cool overnight and will see how it goes tomorrow morning.

    Also with the screws set at that point, when i put the choke on, instead of making the engine rpm low it now bumps up the revs to about 4k rpm. Thats more inline with how i remember my old across' doing it.
     
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Makes sense to me. You should be able to get the range narrowed but it might require setting the synch with vac gauges. Do you have a 'Carbtune'?
     
  9. Jethalter

    Jethalter Active Member Premium Member

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    I got carb sync gauges x 4. I used them last time. But will go over it again tomorrow and see how it is.
     
  10. Jethalter

    Jethalter Active Member Premium Member

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    So this morning, partly good news, no fuel leaks, that small 50c puddle is gone, so float needles and seats are working.

    Bad news is with 4 turns out, its still not enough, it wants to be around 6.5/7 turns out on the mixture screws. This seems like a lot.

    So if my theory is correct, if i used a 32.5 pilot instead of 30, that should bring the turns back in line ???
     
  11. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    That is a lot. Pilot screw o-rings and washers are good? Pilot jets are clear?
     
  12. Jethalter

    Jethalter Active Member Premium Member

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    Jet are clear, i re cleaned them all before assembly. The orings and washers are ones you supplied me in the green kit
     
  13. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    Factory settings are 1.5 turns out , have you pulled them and checked that there is the screw, spring , metal Washer and rubber seal ?
     
  14. Jethalter

    Jethalter Active Member Premium Member

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    Yup i know how far off factory it is, i have had them out when i took the carbs out yesterday. everything is there
     
  15. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    Id say there is a blockage somewhere and you are having to compensate your air fuel mixture.

    Can you try this ?

    Remove your air fuel mix screw, remove your pilot jet, spray three bond or similar carb cleaner down the air fuel mixture screw hole and verify it is coming out the pilot jet hole, if it does, put a finger over the pilot jet hole and you should see it come out of the air jet on front of the carb and also from the cylinder head side of the carb.

    this vid shows the pilot circuit best, while cleaning the mains and pilot is important, making sure these passages are clear and working correctly is super important to get them running right. If that fails then id be looking at the choke plunger seals, maybe they have let go and are leaking air which is messing with your mixture.



    that is all I can think it could be.
     
  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Oops! Oh c'mon Blair, do at least try to keep up.
     
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  17. Jethalter

    Jethalter Active Member Premium Member

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    All of the above is starting to paint a picture.

    Screw out to make it richer, no air leaks on the boots to the head. Took the carbs out again, bowls off, pilots out, and they arn't clean no more. 90% blocked, and when i fitted them yesterday they were spotless clean.

    So its a **** in the tank issue. Took the fuel tap out and thats fairly clean except for a little sediment on the gasket.

    I'm gonna try a seperate tank for the moment, put hte carb in spotless clean again, and retest and see what happens. If it doesn't fault, then i know i have to remove the rear half the bike to get the tank out, clean and reseal it.
     
  18. Jethalter

    Jethalter Active Member Premium Member

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    I'll report it back in a couple of days when i make some progress on it, its gonna take some time.
     
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  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Sounds like you have it solved.
     
  20. Jethalter

    Jethalter Active Member Premium Member

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    Think so, bottom of the tank looks to be rusted. So its got a filter at the tank petcock and considering options.

    By options i mean the idea of an Aluminum tank. Never rust, thats one option.

    What im going to go with at the moment, is see if this filter is enough to stop **** going through and see how quickly it clogs, when i put my other frame on the jig i'll have the tank out and inspect that one, if its good then straight swap most likely, if its bad then i'll make some tanks up.
     
    Last edited: May 18, 2019

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