Keihin CR31...some questions

....finally I got them mounted, the keihin CR31s on my 750 Commando. It`s a tight fit, but once installed, they look like right in place....

My questions:
-- how to start the bike?
the choke -jets supplied by the provider of these carbs was 50....FAR too rich.
I`ve changed them to 40...still not much better, even with the choke lever only slightly opened.
without choke the bike at times starts like a first-kick-starter, at times I have to kick a lot of times...
the smallest choke jets available for the CR`s seems to be the 35....worth the trial?
or is the starter circuit on these CR`s fundamentaly "primitive", as some posts about CR`s(on other bikes like hondas etc.) point out?

-- bellmouths/velocity stacks...
my provider sent the carbs with the long version of the bellmouths....up to now looking up photos of JS or others I can find them equipped only with the short version of the bellmouths.
any experiences with any relevant effect of the length of the bellmouths ....before spending eventually useless money for a pair of the shoerter ones?


thanks for any suggestion


christopher

I've had a pair of CR 33mm carbs on my 920 for quite a few years now. From cold the best way to start it is choke full on, open the throttle about 10% & kick. If your bike had an electric start there would be no need to even open the throttle. As soon as the engine starts, nearly always first time, close the throttle & control the tickover with the choke lever. When starting a warm engine just turn on the ignition & kick, do not open the throttle whilst kicking as there is no need.
I'll check my notes later & let you know what size jets I'm using.

Martyn.