Is it weird to need throttle to start? But runs beautifully Hawkeye 150

[tt250vabeach]

Originally Posted by Thumper

Oh. I think I found it (a CV carb, vacuum operated, called PD24 CVK). I see, it does have an electric choke!

My guess is that it is normal for that carb to need a throttle twist to start.

If you haven't looked into it, your throttle opens a butterfly valve in the throat of the carb, exposing the carb to the vacuum generated by intake valve opening. The vacuum is vented to the cap over the diaphragm that is connected to the slide-which pulls the slide up. These carbs were common on lots of multi-cylinder Japanese bikes, like the GS series (except the first few years which had direct slide type carbs).

This is very different than the typical direct slide control carbs on the dual sports which lift the slide with the cable.

CV carbs don't open more than the engine needs, which you can easily do with a direct cabled slide. It is easier for the manufacturer to set it up and tune it to get the right amount and mixture of fuel/air. Nifty device.

Thank you for the info! And the detailed explanation. I feel better!