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Need help with an 05 YZ450F

543 views 2 replies 2 participants last post by  zeus-9R 
#1 ·
It has an issue with constant popping at steady throttle above 1/8 throttle. I have messed with the main jet and needle positions, but the popping does not change. The carb has a MSR air screw, and Boyesen quick shot accelerator pump cover. The bike has done this from the time I got the bike from the previous owner. The bike runs great on the gas hard or off the gas. It just does it at a steady throttle. Any ideas?
 
#2 ·
i have the same bike, am familiar with this carb. does the bike have alot of use on it? did it sit for a long period? i would do 2 things first, 1 check the carb by spraying cleaner through the pilot circut, make sure its coming out the 2 holes in the bottom of the bore and that the pilot jet isnt clogged or partially blocked, check the emulsion tube wich is the brass tube the needle goes down into and is usually cross drilled, look down into the tube and make sure the hole is still round and that the needle didnt wear it to an oval shape, and 2 check for air leaks and plugged vents,,,,,,, does the bike idle ok?
 
#3 ·
The bike does not look to have a ton of hours on it. It was a race bike and raced 6-8 times a year. I don't think it sat for long periods with out being rode. I have taken the pilot jet out and it is clean. The bike starts first kick and ideals fine. It runs great everywhere but at a steady throttle input above 1/4 throttle. I may just need to pull the carb and clean it good, but it does not look bad from jets I have pulled from it so far.
 
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