07 450 Backfire

My '06 was delivered to me with a 42/165 installed, and a 160 & 170 in the parts bag.

Same here and I just picked up my '06 2 weeks ago.

what setup should i be running for a 07' yz450f. My bike is poping pretty bad when you let off the throttle. 850 ft above sea level.

what setup should i be running for a 07' yz450f. My bike is poping pretty bad when you let off the throttle. 850 ft above sea level.

45/165 - 45/170 just like everybody else. Then adjust your air/fuel screw as needed. The 06 and 07 are basically the same bike. I run a 45/170 on my bike. I was having hesitation with the 165, and the 170 cleared it up. once it heats up again I will go back to a 165.

Actually 48 pilot 170 main seems to be the more popular setup for under 2000 feet. You could try a 45 pilot and if it's still popping a lot then you know you still have one more to go. The nice thing is that it's easy to change out pilots and mains (or put in a fuel mix screw for that matter) without even taking off the seat. Since it only takes a couple minutes you don't lose anything trying out different combinations.

I am new here and I appreciate the help. I just bought my 450 and I was curious about the backfire, I am in Hawaii so it is always warm and low elevation. I will give 48/165 a shot.

I am new here and I appreciate the help. I just bought my 450 and I was curious about the backfire, I am in Hawaii so it is always warm and low elevation. I will give 48/165 a shot.

I'd be ready to try a 168 and 170 as well as I tried 165-170 and the 170 worked best for me. Mazatlan, Mexico should be about the same climate as you depending upon what Island you're on and if anything I imagine it's a little cooler where you are so I bet you end up with a higher main then the 165 but each bike is unique.

I've had good luck with 45/165 in my '06.

That's what Zip Ty put in my carb.

I live in so. cal. and for my 07 I am using

162 main

48 pilot

50 leak

AP mod

2-3 turns on fuel screw.

May try a 165 main, but as of now no popping and no hesitation.

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