Quote:
Originally Posted by bogieboy
i agree with Megadan... theres not going to be enough airflow thru the head to support the added capability of the 28mm, this also presents bigger issues, in that there will be a larger vaccum drop when you crack the carb open, causing stumbling and poor low speed throttle response.... just think how a race car idles, and how they perform at low throttle inputs... not too great..... but wide open is where they want the performance, so they size the carb to flow the best wide open.... while sacrificing low speed driveability....
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A 28mm venturi, or 28mm smooth bore carb wouldn't give up much on the low end, and really help on the top end of the rev range. That is about as large as I would go if low RPM power still matters somewhat. A 30mm is about the largest I would recommend going, and it will lose most of its low RPM throttle response, and without some head work be a complete waste of time.
I do plan on running a 30mm smooth bore after head porting, but I already expect the resulting loss of low end. Currently I have a PWK clone with a power jet, but I may also get my hands on a Mikuni VM30-83. if the flat slide behaves in a way I don't like. My backup plan is to drop back to a 28mm OKO/PWK carb. I kind of have a small collection of them now. All I need is a 34mm to round out my set.