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Across, 15-20% power loss.

Discussion in 'Suzuki 250cc In-line 4's' started by sarahb, Jan 8, 2016.

  1. sarahb

    sarahb Well-Known Member

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    Riding home the other day, maybe around 90km/hour, went to change up to 4th or 5th gear, sudden loss of power, maybe 20% and change in engine sound to a deeper sound.

    The plugs are ok.

    I suppose the obvious thing is carbies.... plan to clean them completely as soon as I can...

    Have also ordered 4 slide holders to change... because why not.

    But did an oil change recently. Went with a semi synthetic.. a cheaper one from SuperCheap. Fuchs Super 4 10w40. Was hard to find any info on whether it was an ok choice.

    Anything I'm missing?

    Ta
     
  2. kiffsta

    kiffsta Senior Member

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    I would check your slide holders and make sure one hasn't dropped, its a common problem on an across, just pop the top plate off your carbs and check them
     
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  3. Willrcr15

    Willrcr15 Well-Known Member

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    You'll find something obvious, wouldn't like to guess with any confidence.
    If it was carbies you'd notice an un even firing like a miss.
    If it's a failure affecting all cylinders then look at the parts common to all cylinders.
    Air box dislodged or a breather hose come off
    I saw a blocked exhaust once due to a piece of rag used in the inlet port that got overlooked & the exhaust was fitted & blew the rag into it & as you can imagine there was a significant loss of power
     
  4. sarahb

    sarahb Well-Known Member

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    its not an even loss of power. i think if i'd never ridden it before i wouldn't think anything was wrong. the change in sound is the most obvious different and some flat spots. and just not as zippy. you've just reminded me that i need a new air filter..

    the oil full line, should this be read whilst the bike is upright, or on its stand?
     
  5. Phil

    Phil Senior Member Contributing Member

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    A new air filter will do no harm and the bike should stand upright whilst checking the oil level.
     
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  6. Willrcr15

    Willrcr15 Well-Known Member

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    See if something has tightened up creating drag, chain, wheel bearings, tyre rubbing on the swingarm ??
     
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  7. sarahb

    sarahb Well-Known Member

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    Thanks guys. I've been away so haven't had a chance to do anything. Getting back tomorrow and my 4 slide holders should be waiting for me.

    I think I'd better remove about half a litre of oil. If this has caused loss of pressure what are some of the possible effects?

    7 of the 8 screws which hold the lids on the carbs were fine but the 8th one wouldn't budge and I stripped it :( just so old and soft. Doesn't help that downward force is lost as it's connected to the sloppy air box.






    Sent from my iPhone using Tapatalk
     
  8. sarahb

    sarahb Well-Known Member

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    so i found this on youtube.. an apparently clever trick removing some excess oil :)

    its very short 20 seconds..

     
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  9. Phil

    Phil Senior Member Contributing Member

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    Happy to explain this method as I have done it myself and it does work :thumb_ups:
    Take any spray pack....windex was used in this demo
    Unscrew the top off and insert into the engine, obviously where you fill with engine oil
    put the empty container over the sprayer and pump away. I removed excess oil very quickly.
    Hope this helps
     
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  10. sarahb

    sarahb Well-Known Member

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    thanks phil, i worked it out eventually... :)

    i like the idea of this method a lot more than the one i had imagined. a lot less messy :)

    also found some good tips for working with stripped screws. hopefully the duct tape trick will work first go :oops:

    ordered air cleaner. this thing is going to be completely reconditioned at this rate.

    just needs a respray...
     
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  11. Willrcr15

    Willrcr15 Well-Known Member

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    If you've got the time & energy, replace all the phillips head screws with stainless steel socket heads & you'll never have a problem ever again. just be gentle when tightening up as you'll get a lot more force on then now.
    [​IMG]
     
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  12. Aaron81

    Aaron81 Active Member

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    Another trick for the stripped bolts, if there is enough room get a hacksaw blade and cut from one side to the other on the top of the screw and this way you should be able to fit a bigger flat blade screw driver into it :)
     
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  13. sarahb

    sarahb Well-Known Member

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    Never had a girl been so happy to finally get off that 8th screw and find a fallen slide holder! Yippee.

    Replaced, cleaned gunk.

    Removed excess oil.

    Tried to do the carb balancing with plastic bottles but the plastic was too soft so off to hunt for glass bottles today.

    Test drove. Power back.

    Went to work. Got home and air filter had arrived. Put that in this morning and oh my golly gosh I have a new bike.

    I have to relearn to ride now. It's totally different. So smooth. The change I was expecting after removing 1 inch deep rust flakes and refining the fuel tank.

    Wow

    Now I have to work out what that knocking is near my left foot. But that's fodder for a new thead... :)

    Thank you all once again


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  14. kiffsta

    kiffsta Senior Member

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    awesome work Sarah, glad to hear its sorted.
     
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  15. Phil

    Phil Senior Member Contributing Member

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    Ain't it grand when a plan eventually comes together, now time to enjoy the ride :thumb_ups:
     
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  16. sarahb

    sarahb Well-Known Member

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    Offending slide holders :
    [​IMG]




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  17. Joker

    Joker See "about me" for contact details. Contributing Member

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    Glad you've sorted it.

    One thing though... knocking down low is not good, could be really not good....
     
  18. sarahb

    sarahb Well-Known Member

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    Ugh.

    What are you thinking?

    Chain? Sprockets?

    Is it dangerous? Is the back wheel going to fall off?


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  19. Aaron81

    Aaron81 Active Member

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    engine bearing
     
  20. JiffyJoker

    JiffyJoker Well-Known Member

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    Loose chain slapping the front sprocket case from my experience. Tighten it. Slack of chain should be 1inch

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