I thought I ask a few question to see if I’m on the right track

[wymondham1979]

Hi Guys as it's a typical British summer (80mph winds & monsoon rain LOL)
I thought I ask a few question to see if I'm on the right track

(1) The single petcock on my bike appears aftermarket with no vent? Is this type ok for the bs 38 carbs I'm running ? Or should I get a vacuum one or a second one?

(2) Do Non Vacuum type petcocks need the petrol tank venting?

(3 ) How can I tell if the auto advance unit is working correctly ? Should the arms when pulled outwards with a finger click back naturally via the spring?

(4)I have scoured this forum and the internet to try to find out if an xs650 spoked or mag front wheel is a directed replacement for my front xs650 mag wheel ?as I'm thinking about putting the front mag on the back with Omar's adapter ?Is this a direct swop ?are there any other things to take into consideration such as suspension ,chain movement ,spacers ,rear mudguard etc,

(5)If it takes three men one hour to fill a bath using one litre jugs? Why don't they just turn the taps on?

Many thanks

 

[weekendrider]

The tank vents through the cap.
One petcock is sufficent.
Yes the springs should snap the bobweights back into place.
You should also check for over advance with a timing light.
Watching the bobweights while increasing rpms the weights should lift with a steady easy spread. Several years ago I tried different springs and found all had problems.
And none would/could match the spread and retention of OEM springs.
They opened to early, too late or would go from nothing to full advance with no in between.

 

[pamcopete]

It's important that the weights retract completely in idle and important that the weights extend to full advance at 3,000 RPM, but what happens in between is not important. The engine idles at 1200 RPM and reaches full advance at 3000 RPM, that's just 1700 RPM of operation during which not much is going on. The engine spends most of it's time above 3,000 RPM anyway, which is where it develops it's maximum torque and horsepower. Think of the advance mechanism as a retard mechanism which retards the spark for easier starting and smoother idle.