Loud Pops & Sputters until motor is Hot?

I Know my bike is cold natured, but something is not right.

Recently started poping and sputtering for the first 10 minutes of riding. I already warm the motor up for a few minutes before hiting the woods. Once the motor gets hotter it runs fine. I never had this problem until a few weeks ago.

I took the carb apart and found no dirt or anything clogged, the float measured in corect at 9mm.

I checked the valves 2 months ago and all was in spec.

I have the WR carb gutted to YZ specs. I dont think I should change any jetting because the motor ran fine for 3 years with the jetting I have.

I tried cr9e and have always run the cr8e. Same popping

Should I hook the grey wire back up?

Could it be muffler packing????

If anybody has had the same problem Please advise me of the cure.

Star, Did the bike all of the sudden start doing this or did you pull the carb apart and when you got it back together it started doing this?


All of a sudden.

Pulled carb apart to try and fix.

Thanks for asking.

Just a couple considerations:

Hope your not having valve trouble, that repair is challenging.I know sometime a worn exhaust valve seat can cause this noise as combustion leaks into the header.

Is there a possiblity of bad gas causing pre ignition?

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