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Help GSXR250 GJ72A - Power problem

Discussion in 'Suzuki 250cc In-line 4's' started by Luejay Orboc, Nov 20, 2024.

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  1. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Is it normal for this bike to lose power even after it is successfully climb an incline road in a 2nd or 3rd gear?

    When in that situation, it feels like it is in neutral state. The bike can rev but can't give enough power to run.

    Just for idea how incline the road is, the 3rd gear can but barely enough for a success climb.
     
    Luejay Orboc, Nov 20, 2024
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  2. Why?

    Why? Well-Known Member Premium Member

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    Sounds to me like starving for fuel
     
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    Why?, Nov 20, 2024
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  3. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Do you think it's about tuning the carb? I have done cleaning it.
     
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    Luejay Orboc, Nov 20, 2024
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  4. Why?

    Why? Well-Known Member Premium Member

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    I was thinking kinked fuel line or blocked filter, enough fuel to keep it running but no enough under load. I had a kinked fuel line on my FZR and it was doing the same thing.
     
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    Why?, Nov 20, 2024
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  5. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    You have a point sir. Mine really has a kinked fuel line, one that is connected from the fuel tank to the carb (and also does not have the filter). I already restore its shape using a plies but I guess it is still really one of the reason why. If not, maybe on the other lines.
     
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    Luejay Orboc, Nov 20, 2024
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  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Can be many things

    Blocked fuel tank vent .... causes a vacuum and restricts fuel flow .... ride with the fuel cap slightly open .... not with a full tank though of course

    Is it running on all 4 cylinders? .... when its warmed up, spray a little water on each header and see if they all sizzle

    If the fuel lines are old and/or bent , replace them .... long curves with soft rubber

    The carbs should be synced after a rebuild but I doubt that will cause a major power loss

    Or maybe you have been drinking too much Red Horse or Tuba while working on the bike and your now too heavy :lolsign:
     
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    GreyImport, Nov 20, 2024
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  7. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Hahah. Man, have you been to Philippines? Tuba is a native thing here. Expectedly most of foreigners should not know it. Cool of you.

    Anyways, I quite can't imagine how to test the cylinder as you said. I am just new to motor thingies and still learning even the basics.

    Imma try the rest that I believe I know though. Thanks!
     
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    Luejay Orboc, Nov 20, 2024
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  8. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    My ex is Cebuano .... and the rest is ancient history :lolsign:
    I have tried Tuba .... man that stuff is deadly :headbang:

    We all start at the beginning :D

    These are the exhaust headers .... yours will look similar and of course end at the back with a muffler or silencer .... sitting on the bike , the cylinders (and therefore each header pipe ) are numbered from the left #1 ,2,3 and 4

    Where they first curve down is where u spray or squirt a small amount of water on each pipe 1 at a time while the motor is running and bike is warmed up.... if it turns to steam then obviously its hot so the cylinder is firing ..... if it just runs off , then maybe that cylinder has no spark or no fuel from the carby and is not firing

    headers.jpg 2.jpg

    Also check that you have the spark plugs leads going from each coil to the correct plugs .... also check the ends of the leads and plug caps arnt corroded.

    Pinned - Ignition coils / HT leads/ Spark plug configuration - Inline 4s | 2FIFTYCC.COM - Home of the Quarter Litre

    Pinned - Trim your Spark Leads | 2FIFTYCC.COM - Home of the Quarter Litre
     
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    GreyImport, Nov 20, 2024
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  9. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Whoa, that's unexpected.
    As far as I know there are 2 or 3 flavors of Tuba, but I only like no other than the sweet one.

    I think this contributes a lot of possibility to the cause of my problem. Secondly are the fuel lines and blockage.
     
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    Luejay Orboc, Nov 20, 2024
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  10. gyro gearloose

    gyro gearloose Active Member

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    air filter or the lack of air filter? someones been stupid and drilled the air box?

    ummmm... or is it the clutch slipping?

    "feels like its in neutral state" suggests its running fine... just not getting power to the ground...
     
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    gyro gearloose, Nov 20, 2024
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  11. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    I mean the fuel filter. Like this image bellow
    That's right. It finely run in totally plain road just not in plain road that needs to be climbed first.
    .[​IMG]
     
    Luejay Orboc, Nov 20, 2024
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  12. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    It turned out that I don't have to climb in an incline road to experience it. Even in plain roads, it also happens. When shifting to 3rd (or any higher than 1st gear) at the wrong time, the bike obviously struggles to give power, then when I rev it, it feels like I'm in neutral as I said or sometimes choked. So, I have to downshift it one step to get through it.
     
    Luejay Orboc, Nov 22, 2024
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  13. Linkin

    Linkin The Mechanic - Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    If it is dependant on road speed and gets worse as you go faster, it definitely sounds like a fuel flow problem.

    The usual causes are:

    Blocked breather in the fuel cap - when the problem occurs, open and close the fuel cap then immediately re-test. If it improves, you have a blocked breather causing a vacuum lock. Usually can be cleared with compressed air gun down the breather. In some cases they are blocked solid, mostly where the diameter of the breather tube is small (common on Ducati and other Euro motorcycles), in which it needs to be manually cleared. I have had success using small diameter drill bits - by hand, no power tools.

    Water in the fuel tank - won't burn and provides no power, causes poor running and low power, in some cases will not start until carb bowls are drained (you should do this and see if the fuel is clear or brown when it flows out)

    Clogged fuel filter - blow through the fuel filter, it should flow freely, if there is any resistance then replace the filter.

    Clogged fuel tap - caused by water, rust and sediment build up in the fuel tank - worth checking the carb fuel passages and float needle seats as well.

    Kinked fuel line - will cause fuel starvation, low power. The fuel line might look OK when you lift up the fuel tank, but gets folded when the tank is fitted where it should be. You will need to look closely when the tank is fitted.

    You need to fully inspect the complete fuel system starting with the tank, cap, fuel tap, fuel lines and filter, and then finally carbs at the end.
     
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    Linkin, Nov 22, 2024
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  14. Frankster

    Frankster Grey Pride...Adventure before Dementia Premium Member

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    Take the air filter out of the airbox
     
    Frankster, Nov 23, 2024
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  15. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Might try this.

    Both carb and tank are newly cleaned. But I still have doubts tho.

    I don't have a separate fuel filter that sits with the hose that time. Not until now. Just recently bought a new one. But it didn't help tho. But its tap has its own filter so I might replace the tap also. So kinked fuel line (referring to the hose that connects the fuel tank and carburetor) is not the case. Not sure if there are other fuel line that I have to look for.
    I'll try that as well.
     
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    Luejay Orboc, Nov 26, 2024
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  16. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Already removed the air filter but didn't have the time to test it cause I'm heading out to work. Maybe tomorrow.
     
    Luejay Orboc, Nov 26, 2024
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  17. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Luejay Orboc, Nov 26, 2024
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  18. Linkin

    Linkin The Mechanic - Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    upload_2024-11-26_19-51-10.jpeg
     
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    Linkin, Nov 26, 2024
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  19. Linkin

    Linkin The Mechanic - Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Are those dodgy self tapping screws? If so, you need new clamps along with new manifolds.

    gsxr.jpg
     
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    Linkin, Nov 26, 2024
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  20. Luejay Orboc

    Luejay Orboc Ljay Premium Member

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    Yep, you're right. Problem is that I think a compatible manifold is a headache finding.
     
    Luejay Orboc, Nov 26, 2024
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