I am new to the forum just wondering if there is a way to search previous threads to see if my question has already been answered.

I bought a brand new MB in 2007 and it has been a pain in my butt ever since. It will run like a raped ape for hours on end, until the temps start dropping into the 30-40 and it will go a couple of miles and starts losing power, it just runs rich till it chokes itself out and dies. So i though "carb icing" its not, i have been through that scenario like a dozen times....i have gone through all the associated scenarios also (i.e. moisture, running it hotter, testing KV on the spark, moving the tank, adding auxiliary pump) and i have decided its not a fuel issue.

I have had it in 2 times to dealer, and both times they told me "nothings wrong with it" the week after the last time i had to paddle for almost 6 hours to get back to the boat launch. They have been zero help, and to be honest they have been down right pricks about it. I have taken it to a local small engine shop and they told me they couldn't find anything wrong with it either, but that it might be dropping one of the jugs out, as it gets hot, so the next time it did it i shorted each side out independently and both showed a drop in RPM( i.e. they are both getting spark) I am out of ideas, i have tried everything i can think of, i am about ready to pull the engine and spend the $1700 for a new 21 as it will bolt up the same on the frame.

Does ANYONE have any ideas, any info is much appreciated

do you have a mikuni carb on it?

i would think in the cold weather you shouldnt be running richer.cold weather will make a motor run leaner. and you say it runs its ass off in mild weather. it sounds to me like you runnin lean.just my thought