CRF450R 02 not running all that good

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Nov 24, 2003
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#1
I Have a huge problem with my freinds crf450r from 2002
The thing is that it bangs/shots in the exhaust very much every time that the throttle is shut off it also runs uneven i idle. Over the winter the engine have gotten a new Piston (original parts) I have checked the valves, and the Camshaft timing is absolutly correct. The engine tends to be running very hot (exhaust pipe is very red, more than normal) we have checked ignition timing with a timing light and it also seems ok.
I am kind of running out of ideas :think:
please give me a hint
 

Thump

Jr Admin Type
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Jan 17, 2000
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#2
Is the gas good? If it has been sitting for a while it could be bad and some race gasses are hygroscopic, meaning if not in a sealed metal container (not plastic) they will absorb moisture.
 
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#4
Have you adjusted the fuel screw it may need a half a turn out

danielvagn said:
I Have a huge problem with my freinds crf450r from 2002
The thing is that it bangs/shots in the exhaust very much every time that the throttle is shut off it also runs uneven i idle. Over the winter the engine have gotten a new Piston (original parts) I have checked the valves, and the Camshaft timing is absolutly correct. The engine tends to be running very hot (exhaust pipe is very red, more than normal) we have checked ignition timing with a timing light and it also seems ok.
I am kind of running out of ideas :think:
please give me a hint
 
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Nov 24, 2003
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#5
update

Yesterday we tryed to mount the complete carburator from my bike (crf450r 2004) and then the bike runs perfect. we kind of suspect that maybe the throttle position sensor is not working right, but when we read in the honda book there is 2 different resistans messures on the sensors the 2002 is 510 ohm's and the 2004 is 5000 ohm's. But when we messure them they are the same.
anybody out there who have tryed trobble shutting on a faulty throttle position sensor.

I will of course return when and if we find the problem.
 
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#6
danielvagn said:
please give me a hint
Clogged pilot jet / pilot air system. :thumb: