Loud Pops & Sputters until motor is Hot?

[hsstar]

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.

[Dan_Lorenze]

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?

Dan

[hsstar]

All of a sudden.

Pulled carb apart to try and fix.

Thanks for asking.

[waynewr]

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?