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Discussion Starter · #1 ·
Hi, so I have a 2001 nsr jc22 has had a fresh top end rebuild and will run well when starting up but when I go to ride it in 1st is all good but 2nd onwards It rides fine up to 5k rpm but then it will start to lose power I let off throttle and bring it back on and it goes again till it passes 5k rpm but some times it will pull past 5k with no problem it will struggle to pull up hill and sometimes has no power at all as if it is starving for fuel yet I had upjetted it nothing changed now I have standard jet back it still the same I have cleaned carb a number of times new spark plug new coil lead and cap anyone have any ideas could it be low float crank seal I really am stumped.
 

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Discussion Starter · #3 ·
First make a run with open fuel cap(there is a vent in the cap it might be clogged) then check the carb float height and fuel passage between carb and reservoir there must be a fuel filter!
The fuel runs freely from tank to carb and sometimes will run past 5k rpm but then a minute later starts playing up as if the fuel supply isn't there then is there but only does it in 2nd gear onwards as first gear can rev way past 5k rpm so I was thinking it may be blockage it fuel cap breather hole or float level wrong and but unsure on what to do with float level.
 

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The fuel runs freely from tank to carb and sometimes will run past 5k rpm but then a minute later starts playing up as if the fuel supply isn't there then is there but only does it in 2nd gear onwards as first gear can rev way past 5k rpm so I was thinking it may be blockage it fuel cap breather hole or float level wrong and but unsure on what to do with float level.
Start with fuel cap! you can easily check it while riding with open cap! Then blow the petcock with compressed air, it might be clogged if your tank is dirty or rusty. Did you change the air filter ? You can find the correct float heigh in the service manual carb chart !
 

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Discussion Starter · #5 ·
Start with fuel cap! you can easily check it while riding with open cap! Then blow the petcock with compressed air, it might be clogged if your tank is dirty or rusty. Did you change the air filter ? You can find the correct float heigh in the service manual carb chart !
Ok thank you I have cleaner fuel line and have ran tank into a bottle and the flow is good so filter is clean and running smoothly, I will take the bike out when weather is good enough and try the fuel cap open as I ride and if still the same I will look into the float a bit more and if it's none of them I'll dig a little deeper as I have been told that it could be a stator/pick up problem or a crank seal problem is that possible?
 
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