US-41 the newer version
 

Hey has any one out there ran the newer version with the bigger carb and the different muffler? How does it do? Do I need to put the Q52 carb and b&b muffler on this one to?

Thanks David

US 41 carb
 

I was one of the first ones to start the Q-52 carb trend going on the US 41. I had one of the older ones. I don't know what carb they are putting on those engines now. If I were you, I'd run yours and see what kind of rpms you get with an 18X10 Pro Zinger or an 18x8 regular Zinger. They should be above 7600 rpms. Also, get rid of the stock muffler. We run straight headers on ours and the open exhaust really makes this little engine come to life along with the right prop and carb. If you can get close to 7800 rpm with the carb it comes with by opening up the exhaust, then I wouldn't change the carb. If you are down in the high 6000 range to low 7000 range once you run the open exhaust, then you've got to change the carb.

us 41
 

Thanks for the info fighter pilot the new one does come with a different muffler to and I was wondering how the combination worked. The rpm #s you gave was that out of the box or after break in?

Thanks David

US-41 the newer version
 

I've got one of the new version .41s on the way, and the exhaust looks to be vastly superior to the older version. I would think that with the new design exhaust it should be okay. Looks to be alot less restrictive. Guess I'll see shortly. :D

us 41
 

I agree I think the new one will be better. I was hopeing some one out there has already ran one of the new ones to let us know how it did

Thanks Again
David

US41
 

The muffler that comes on them now is a lot better than the old one, BUT, it is NOT ANY BETTER in terms of flow. It still takes a bunch of rpm off the top end.

US-41 the newer version
 

IS there a less restrictive Pitts style muffler out there that wont hurt the top end RPM range, but is still reasonably quiet as far as IMAC rules go?