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Discussion Starter · #1 ·
Hi !! I am having some problems with my 08' KFX 450, the bike bogges down at half throttle but keeps on going. i have tested and cleaned everything. checked and tested wires relays etc.. has anyone had this problem ?
 

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Hi !! I am having some problems with my 08' KFX 450, the bike bogges down at half throttle but keeps on going. i have tested and cleaned everything. checked and tested wires relays etc.. has anyone had this problem ?
Fuel pump strainer might be dirty/clogged lowering your fuel pressure...https://www.kfx450hq.com/threads/how-to-clean-fuel-pump.13807/

TPS out of range adapter to test part # 57001-1538 ...see pic


Valve clearance might need to be checked...
Valve Clearance: between cam and valve lifter
Standard:
Exhaust 0.17 ∼ 0.22 mm (0.0067 ∼ 0.0087 in.)
Inlet 0.10 ∼ 0.15 mm (0.0039 ∼ 0.0059 in.)
 

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Discussion Starter · #3 ·
Hi Dust Devil , Thanks man , i removed the pump and cleaned everything properly. i saw that pressure regulator valve has moved slightly, i made a washer to keep it in place put back the pump and went for a quick ride and it goes like a demon! I'm going to test drive again today and give feedback!
 

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Discussion Starter · #4 ·
Okay so just an update, bike still does the same. ounce i put everything back together i did notice tiny bubbles coming from the pump when it primes? Any body seen this before?
 

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Okay so just an update, bike still does the same. ounce i put everything back together i did notice tiny bubbles coming from the pump when it primes? Any body seen this before?
Do a fuel pressure test... 43 psi Idle to WOT
 

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Discussion Starter · #6 ·
Do a fuel pressure test... 43 psi Idle to WOT
HI !! Yes the pressure is 3bar/43psi , starting to think it could be the TPS. I just don't have the TPS sensor cable. Will check valve clearance later today. Thanks
 

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Discussion Starter · #8 ·
Check it with voltages.
HI, So an update on my bike. checked everything and all is working and in spec. so i removed the fuel pump relay and reconnected the breach ( pervious owner did this ) for straight 12v, the bike now has full power and not bogging at all. runs 100%! but now the EFI light is on. is it safe to leave it like this?
 

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HI, So an update on my bike. checked everything and all is working and in spec. so i removed the fuel pump relay and reconnected the breach ( pervious owner did this ) for straight 12v, the bike now has full power and not bogging at all. runs 100%! but now the EFI light is on. is it safe to leave it like this?
No! If the F.I light remain ON you need to check for error code...Find & ground the orange wire to the frame..
 

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Discussion Starter · #11 ·
No! If the F.I light remain ON you need to check for error code...Find & ground the orange wire to the frame..
HI Dust Devil, okay so i check the F.I code and it was the fuel pump relay, so i reconnected the relay and removed breach. F.I light was gone. Checked all volts om relay and also 3sec prime volt, all is in spec , 12.8v. bike starts fine but still bogges down mid throttle... :-( it sounds like the motor isn't getting fuel.
 

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HI Dust Devil, okay so i check the F.I code and it was the fuel pump relay, so i reconnected the relay and removed breach. F.I light was gone. Checked all volts om relay and also 3sec prime volt, all is in spec , 12.8v. bike starts fine but still bogges down mid throttle... :-( it sounds like the motor isn't getting fuel.
Do you use a fuel programmer if yes.. what make & model..?

Is your air intake stock or has an after market air intake tube..? (stock circled in pic)

What's the fuel pressure @ 9000 RPMs...? If it drops your strainer might be clogged...
 

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Discussion Starter · #13 ·
Do you use a fuel programmer if yes.. what make & model..?

Is your air intake stock or has an after market air intake tube..? (stock circled in pic)

What's the fuel pressure @ 9000 RPMs...? If it drops your strainer might be clogged...
HI Dust , Bike totally stock and intake is also stock. I'm looking for an adaptor to test the fuel pressure again. The struggle is real here in Africa! haha
 

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Discussion Starter · #14 ·
Just an update! i have ordered an new fuel pump, fuel pump relay and ignition coil. going to strip wiring and check throw every thing. I hope i get this fixed! Thanks guys
 
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