Niklas Edlund
Well-Known Member
- Joined
- Dec 14, 2004
- Messages
- 512
Hi guys, I tried the new CMB .21 VAC engine this past weekend with no luck. We have for the last two seasons used the Zoom 21 carb for the Valvola and its an absolute dream to use. The stock CMB VAC carb seems to be not so Zoom like if I may say so...
I unscrewed the midrange needle so it was not in any way close to the spraybar but we could not get the geometry right. When looking at the holes in the spraybar (and blowing air through it) it feels like there would be enough flow but Im skeptical about that. If adjusted to about the same rich level we are used to with the Zoom it was to lean (eventually - when sticking the trigger WOT) on top end. If the third channel needle (Kalistratov/CMD) was adjusted so it was rich enough on WOT it was too rich to launch...
So what do you do for making it work?
I use 60% fuel and a Fat pipe.
Update: the spraybar hole is about 2.0 mm in diamter on the stock .21 VAC carb, possibly 2.1...
/Niklas
I unscrewed the midrange needle so it was not in any way close to the spraybar but we could not get the geometry right. When looking at the holes in the spraybar (and blowing air through it) it feels like there would be enough flow but Im skeptical about that. If adjusted to about the same rich level we are used to with the Zoom it was to lean (eventually - when sticking the trigger WOT) on top end. If the third channel needle (Kalistratov/CMD) was adjusted so it was rich enough on WOT it was too rich to launch...
So what do you do for making it work?
I use 60% fuel and a Fat pipe.
Update: the spraybar hole is about 2.0 mm in diamter on the stock .21 VAC carb, possibly 2.1...
/Niklas
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