Vacuum and fuel line question

[copeland3300]

Hey guys. I'm almost done putting everything back together on the bike. The last thing I'm trying to figure out is the vacuum and fuel lines. I think I know where they go, but I've not had much luck with an exact answer.

http://imgur.com/ES7gl

Based on my picture
A - crankcase breather (I have to get a filter)
B - Left fuel line, goes to fuel petcock
C - Right fuel line, goes to fuel petcock
D - Vacuum line, connected to the carb holder on cylinder 2. I have no idea where it goes.
E - Vacuum line, connected to the carb holder on cylinder 3. I have no idea where it goes.

Also what seem to be nipples that could run lines from the carb holders on cylinders 1 and 4 are capped off. I assume I leave them that way?

Thanks!

[dpotter58]

Hey guys. I'm almost done putting everything back together on the bike. The last thing I'm trying to figure out is the vacuum and fuel lines. I think I know where they go, but I've not had much luck with an exact answer.

http://imgur.com/ES7gl

Based on my picture
A - crankcase breather (I have to get a filter)
B - Left fuel line, goes to fuel petcock
C - Right fuel line, goes to fuel petcock
D - Vacuum line, connected to the carb holder on cylinder 2. I have no idea where it goes.
E - Vacuum line, connected to the carb holder on cylinder 3. I have no idea where it goes.

Also what seem to be nipples that could run lines from the carb holders on cylinders 1 and 4 are capped off. I assume I leave them that way?

Thanks!

vacuum lines to your petcocks? Do you have one to your vacuum advance?

[crazy steve]

D - Vacuum line, connected to the carb holder on cylinder 2. I have no idea where it goes.
E - Vacuum line, connected to the carb holder on cylinder 3. I have no idea where it goes.

Also what seem to be nipples that could run lines from the carb holders on cylinders 1 and 4 are capped off. I assume I leave them that way?

Thanks!

D and E connect to the petcocks, assuming you still have the OEM standard tank and petcocks. This is the vacuum supply that operates them. The two 'leftover' nipples remain capped, unless you're syncing the carbs, then this is where you connect the gauges (after disconnecting the lines to the petcocks).

[copeland3300]

Oh, ok, well that was an easy answer then :P

dpotter58, can you expand on the vacuum advance question? That's on teh left side of the engine, right?

[natemoen]

Oh, ok, well that was an easy answer then :P

dpotter58, can you expand on the vacuum advance question? That's on teh left side of the engine, right?

Yes, the vacuum advance is under the left side engine cover. There is a brass nipple on the #2 carb body. That is what the vacuum advance must be connected to.

[copeland3300]

Nice, thanks!

[copeland3300]

So after doing a little more research, I'm assuming that
A) because I don't recall seeing it
B) because it seems to be for an SF

I don't have an octy on an '80G?

[dpotter58]

nope. they are only on the specials

[GLoweVA]

So after doing a little more research, I'm assuming that
A) because I don't recall seeing it
B) because it seems to be for an SF

I don't have an octy on an '80G?

The Octy's are for the Specials.
If you have the larger standard tank, then you should have vacuum controlled petcocks and thus no need for an octy.

Dwayne, you sure do type fast.

[DGXSER]

A shas been pointed out, each model Standard and Specials incorporated a vacuum valve to control fuel flow to the carbs. For some reason that escapes me, Yamaha went with two different designs, one for the Standard models, and another for the Special models.

On the Standard models the vacuum valve is integrated into the petcocks, on the Special models it is a separate valve.

Why they did not consolidate to one or the other by the 80-81 models I am not sure.

[GLoweVA]

A shas been pointed out, each model Standard and Specials incorporated a vacuum valve to control fuel flow to the carbs. For some reason that escapes me, Yamaha went with two different designs, one for the Standard models, and another for the Special models.

On the Standard models the vacuum valve is integrated into the petcocks, on the Special models it is a separate valve.

Why they did not consolidate to one or the other by the 80-81 models I am not sure.

Maybe it was a space consideration thing.
The special tanks are shorter, so the standard petcock wouldn't fit. (tower's too tall)
The special tank also sits a little lower thus closer to the frame and the standard petcock might interfere there.
JAT.