Calling all mates with Mikuni RS36 experience.

[pgnz]

Yo, dunno, I'll do a vid showing this thing idling like
a dream at full vacuum... I'll slap a timing light
on it at the same time and see what the hell it's reading..

[Turd Ferguson]

if you're running the vac from a manifold sounds like
the hose isn't restricted enough which makes the vac unit
chatter, mine (kiehin 36 carbs) runs smooth as silk at
idle with a fuel hose from manifold spigot, the aperture/restrictor
inside the hose being a small tight-fitting hollow tube, the
tube plugged with epoxy, and a hole thru it from a single
skinny bit of bread-tie wire...  Pulled the wire out when the
epoxy was firm but still setting leaving that tiny hole, it's
only half a mm diameter.. Idle, acceleration and cruise
all running sweet ..

Yeah, I kind of did the same thing so far ... I got me a set of wire gages to measure the ported vacuum hole in the # 2 carb. It is 0.030 inches or 7.6mm. Got me a set of micro drill bits. I am still using the drip irrigation valves because with manifold vacuum you cannot shut of the vacuum signal to the advance unit like the stock carbs where vacuum is ONLY applied when the throttle blade opens (ported vacuum signal). That means with manifold vacuum at idle the engine runs with the static 10 deg. advance plus the full 16 deg advance the vacuum unit provides. SO a total of 26 deg advance at idle is way too much and makes for a very, very bad idle. So I modified the irrigation valve by closing its input side and drilling a .030 hole for damping the signal, but I can still shut off the vacuum signal in city traffic to have decent idle. On the open road you want the vacuum unit to work. It makes for better part throttle response and without the vacuum advance your mileage drops from 38 mpg to 32 mpg in my case.

[pgnz]

if you're running the vac from a manifold sounds like
the hose isn't restricted enough which makes the vac unit
chatter, mine (kiehin 36 carbs) runs smooth as silk at
idle with a fuel hose from manifold spigot, the aperture/restrictor
inside the hose being a small tight-fitting hollow tube, the
tube plugged with epoxy, and a hole thru it from a single
skinny bit of bread-tie wire...  Pulled the wire out when the
epoxy was firm but still setting leaving that tiny hole, it's
only half a mm diameter.. Idle, acceleration and cruise
all running sweet ..

[Turd Ferguson]

Alrighty .. calling all mates with Mikuni RS carb experience. So far my build has gone well ... https://youtu.be/1-yzBGR_Oa4?si=dMBpcPk6D9rGymG1 ... little niggles like fuel line routing and waiting to get about 500 miles before I lay a little more into her .. keeping rpm varying and below 5000 rpm. BUT here is the deal: THose RS carbs do NOT have a ported vacuum spigot like the BS34 carbs. That is generally not an issue (I did what Andy did on his basket case cafe racer and use an irrigation valve) EXCEPT at idle. Without such a port you have full vacuum advance at idle and that makes for a nervous and vibey idle. Actually really terrible. Once you go it's fine but sitting still it's bad. Has anyone drilled a ported vac port (a port that does not provide a vacuum signal until the throttle is slightly opened) into these RS carbs?