Petcock/Fuel Line Routing

[Edisto]

Looking at a few diagrams in older posts, it looks like when bypassing the octy, some of you are running a "Y" or "T" connector that connects the prime and regular nipple of the petcock. Having the prime nipple and the regular on/reserve nipple on the same hose does not pose any problems? Thanks for the input.

[jwhughes3]

special tank?

Are you describing a Special petcock I assume?

I think if you Tee the two petcocks together before they go the carbs then you are getting feed to the carb regardless of whether it is set to Prime or Reserve.

If you swap in the Standard petcocks as I did when I removed the octy I plumbed the line direct to 1 set of carbs and the other side to the other set - they don't crosstalk to simplify the routing of lines on my bike (YOMV).

John

[Edisto]

Yes--it is a Special Tank I am working with. Actually a Special Tank, and an XJ Tank. The XJ petcocks look the same as the Special.

[bikerphil]

Most just cap off the prime (front) nipple. No need for prime anymore without the octy. It shouldn't hurt anything though.

[Bonz]

Hi, I'm gonna chime in with a question, just out of curiosity more than anything.

I have an 80SG, with the Octy, and with the rebuild kits that are available from Georgefix, seems to me in the long run, just rebuilding the Octy is the way to go. The fuel line routing/quantity of individual lines iwith the Octy s not something you deal with much anyway, other than to get it set up correctly.

Other than the Octy diaphragm failing (which is easy to rebuild), which my original Octy has not (I do have a rebuild kit on hand, in case) why get rid of it?

[jwhughes3]

I swapped tanks...

Hbonser,
I swapped tanks to a Venturer from Special (the Special is the only one with the Octy) and since the Standard petcocks perform the function of the Octy on the Special, I removed mine to simplify the lines.

I think if you swap a Standard tank to a Special, then you probably have to go to manual petcocks with positive shutoff (or ADD an octy). The petcocks are not the same on the flange so are difficult (not impossible) to interchange.


Hope that helps.

John

[Bonz]

Just looking at the original post that started this thread, my question was aimed at figuring out if someone is asking the question of bypassing the Octy, why not just rebuild it, regardless of why you are bypassing it.

It goes to the larger, overall chatter about bypassing the Octy in all the different threads over the years. Hope that makes sense...

[jwhughes3]

i see what you mean...

I was putting the emPHASis on the wrong sylLABle in my reading... now I tend to agree with you - short of a tank/petcock swap I would not have gotten rid of the octy because I for one have CRS and those who suffer from this know we NEVER remember to shut off the darn petcocks when done playing.


It really seems pretty simple and ingenious though I am unsure why the Yamaha engineers decided to move it from the petcocks to a separate device.

John

[Bonz]

Some little known engineer in the Yamaha Motor Corporation had a brain flash one day, and just knew if he could convince them to put in the Octy diaphragm (and of course he had one designed to show the boss), it would increase sales of the Special because of the "intense" engineering that went into the bike, thus ensuring his job security.

He knew that 30+ years later, we'd be asking why he invented it, and unless we can find the little dude, we'll never really know.

[cywelchjr]

I think they THOUGHT they were making things simpler? Only a single shutoff valve rather than two, and actually having an off setting on the petcocks as well which the vacuum petcocks didn't have before. Problem is, an Engineers idea of simple is most other peoples idea of a nightmare!

Although arguably there is the advantage that either side can feed all 4 carbs unlike the standard which cannot without added plumbing, but this "simpler" system with it's single point of failure appears to have turned out to be a less than good idea. I don't think they stuck with it, although they seem to have stuck with the vacuum operated petcock as long as they had petcocks.

[jwhughes3]

they don't have petcocks anymore?

I guess I need to ride a more "modern" bike one of these days - actually I knew Hardley didn't have them from when I've rented them, but haven't been on anything else from the 90's up ever.


John

[Bonz]

I enjoy having the Octy on my 80 SG, if only for the fact the bike is 100% stock, and that keeps it that way.

[Edisto]

I have 3 reasons for getting rid of the octy.

1) Possible failure--ie more crap to go wrong, and with the reality of E15 in the very near future, the less I have to deal with in the fuel system, the better.

2) On my 1979 F, the PO put on a Special Tank and an Octy. I just got a Standard tank that I will be working on and painting. I will be ditching the octy on this one anyway, and I do not want to have to re-run fuel lines.

3) On my XJ1100--the fuel lines have been a HUGE PITA to get correct. The in-line filters routed around the carbs seem much easier and forgiving. This is just my $.02.

[natemoen]

Just keep in mind that the special petcocks that you have will not fit tgw standard tabk. The mounting flange is wider on the standard petcock.

[Bonz]

I think what Edisto is saying is he's putting on the std tank with petcocks on it, and thus no octy is needed. The only reason he had one was because of the Special tank already on his Standard, as fitted by the previous owner I believe.