> Rob LaFreniere Wrote:
> -------------------------------------------------------
> I just bought what I hope is a stock 1984 qt50 and want to upgrade it to
> eventually be fast enough to safely commute to work. I think that 40mph
> would be bare minimum.
Sounds fricken dangerous too me :)
If you don't increase the amount of air the engine consumes, you will create a lean condition because you increased the diameter of the carb. The carburetor's venturi reduces the air pressure inside the carb, so that atmospheric pressure can push the fuel (from the float bowl) and air (into the carb) into the engine.
But if you don't increase the engines demand for more air, or find a way to increase air pressure, the pressure inside the carb will increase, and less fuel will be pushed into the carb, and that is how the lean spot is created.
It has been 100 years since I worked on a QT :) They have a great stock exhaust pipe, and it works well the stock cylinders porting. A tuned pipe does not, or at least in my opinion, the power gains of a tuned pipe are not worth the money unless the exhaust ports blow down time (BDT) has been increased to 21 to 23 degrees. 18 degrees of BDT is the absolute minimum, but I wouldn't waste my time building or selling a tuned pipe unless the customer knew that changing BDT was essential to the performance of the engine.
I don't know these companies, but if you are under the opinion that you can bolt a pipe on to any stock cylinder and get decent HP, that isn't true.
With a stock cylinder, you are better off with a 1/2 pipe that only improves the engines scavenging abilities.
Bill M.