fuel and vacuum

[GARTHXS]

Hi there , can anyone give me a diagram of how a 78 standard is routed all have seen is with an octopus , but I dont have one ????

[AlanB]

Hi Garth,

If it is a stock Standard, it should be pretty simple; Each fuel tap should have one big line out. They go to a pair of inlets on the carbs.

The two little lines on the fuel taps are for vacuum; they will go to a couple of the nipples on the inlet boots. The other two nipples should be capped.

There is a vac advance line from the left side engine casing; It goes up to no2 carb body...... NOT an inlet boot.

Depending on the year, you may have a couple of breathers to link to the airbox....... or not.

A different world to the Specials........

AlanB

[DiverRay]

Garth,
On the '78, as stated the large diameter is for fuel, and goes to the BOTTOM "T" between carbs 1&2, 3&4. I like to cross the lines, right side to 1&2, Left side to 3&4. The TOP "T" is a vent and NEEDS TO BE OPEN. It should be plugged into two nipples on the front of the stock air box if available.
The vacuum lines come from intake ports on 2&3.

[mro]

I like to cross the lines

I do that and Prom likes to delete my posts

Not a bad idea to use a couple of in-line fuel filters if you have not already done so.


mro

[GARTHXS]

What is better

Whats better, vacuum advance or a mechanical??

[DiverRay]

The XS1100 has both. The '78 has the MOST total advance, and with the vacuum system it can also retard the advance under load conditions. The reason we can pull away from most bikes without shifting is because of the advance system Yamaha used.
I just replaced the '79 pickup coils and advance unit on daily ride with a set off my '78 engine. I can now go down to 1500 RPM and still not "bog" the motor. I also noticed a little more at the higher RPM range.
Personal preference, I would keep the ignition stock UNLESS I was doing a complete overhaul of the bike. In that case, I would use a "computer" to manage the spark and fuel injection....

[TopCatGr58]

Hey Garth,

If you'll look at this recent thread you'll find some interesting info about Ignition modules, vacuum and cent. advance curves, etc.!
T.C.