I have been playing about with the jetting on the VHBZ carbs on my V50 Mk II and I wondered if anyone else has been down this path.
The original problem was the fairly familiar issue of the engine hesitating coming off idle, it can be very irritating when pulling away from the lights or blipping the throttle on a down-change. There are a few possible causes, one of which is an over-rich pilot jet, causing the engine to bog down a bit as the throttle slide starts to rise and the progression orifice comes into play. On the Dell Ortos, the idle mixture is adjustable with the screw, but the progression mixture is not, it is supplied direct from the pilot jet. So, having been through the exercise of making sure the carbs were balanced and clean, I have changed the pilot jet from 40 to 36. This has made a huge difference, much more than I expected and it’s a big improvement. Idling is much better and the off-idle response is much snappier. So far so good.
But there’s another problem. It always wants the choke on a cold start (fair enough) but it won’t run on choke, you have to nurse it along with the throttle. My Moto Morini with similar carbs will run happily on choke for 30 seconds or so at a fast idle until it starts to warm up, when it starts to get lumpy, then you can close the choke, give it a couple of blips and it’ll settle down to a normal idle. I’m wondering if the choke jets are also a bit too rich, but I don’t have any smaller ones in my collection to try and at about £6 a pop, experimenting would be a pricey business! Has anyone else played around in this area? Any views?
Thanks!
Joe.