Sure stock carb on Honda is 15mm open port hole.
This Honda CH80 carb is 18mm open port hole.
The jetting is stock but can be upgraded.
I have the user manual in PDF format if you'd like a copy.
It fitting together perfectly with the 18mm intake manifolds from http://www.motorparts4less.com/products.php?id=38.
Several changes to the carb needed to adapt to gxh50.
I should have test results in a week or two.
Give me an email and I'll email you the user manual if you want it.
