Fuel Petcock function

[DGXSER]

Ok, As previously posted, my 81 special runs great with petcock in prime, but dies when in ON, diagnosis is that the Octy is probably at fault.

So far, I have continued to run my bike with the petcocks in prime all the time. I shut them off when I am finished riding.

I understand that this bypasses the safety of the vacuum operation of the ON position should the float bowl valve not close for one reason or another. I feel fairly confident that shutting them to off when not in use eliminates that issue. It seems from all that I have read in all the threads on the petcock issue that the alternate solution is to remove the Octy which would seem to be the same thing as running in the PRIME position.

Am I missing something, setting myself up for a problem I am not forseeing?

Thanks for any input or thoughts.

[XSPastor]

Lose it if you like... but I'd keep it.

Guys lose the octy all the time. It's not a problem if you plumb it correctly. Me; I'd rebuild the octy. I like the idea of having the fuel stop automatically, and I also try to keep the bike as stock as is practical. Georgefix sells a octy/petcocks kit on ebay for a reasonable price.

[Ivan]

First thing I would do is check the octy with a vacuum pump. Remove the fuel line form the carb, turn on the fuel valve and apply vacuum to see if the fuel flows. If not, check to see that there isn't a vacuum leak. This was the case on mine, and I had to use a whet stone to make the surfaces of the octy flat again. Other than that, there is a small o-ring that does the actual sealing, which is easily replaced.

Also, make sure you have the advance and the octy vacuum lines in the right place. The advance line should go to the port on the #2 carb, and the octy should go to the intake boot. The port on the carb is ported vacuum and doesn't pull at idle.

Personally, I would not run the petcocks in prime all the time. As I understand it the prime port draws from the bottom of the tank, same as running in reserve all the time. This would end up sucking junk into the carbs or water or whatnot.

Honestly, I think the octy gets ditched because it is misunderstood. It is pretty simple once you take it apart and understand whats going on inside it. I like it as a backup to the petcocks, because I forget ... a lot ... really, a lot. Now, what was I talking about?

[boyat68]

DGXSER:

As Ivan said above, check the vacuum. Also as stated, junk may have got into the petcocks path and blocking the flow even with the position,"run" being served with adequate vacuum. This may mean that you have to clean the tank. You may need to remove the petcocks and check to see if the tower screens are in place.

[DGXSER]

Thanks for the input and support. I may tackle cleaning it all out as it is now highs in the 30's for a while and I figured out yesterday that I personnally am not a cold weather biker. Even with a good coat, gloves, and a full face helmet the wind gets to my fingers and my neck.

I was trying to get an idea of what the downside is to running with it in PRIME all the time. I don't want to remove the Octy just because I like the bike intact and stock as much as possible. But I am also a founding member of the procrastinators club, so why do today what I can put off until.....whenever. Sounds like I am risking sucking junk from the tank into the system ( a notably bad thing). And, as I was concerned about, that I am essentially running on reserve and if I run out of fuel, I am out and a new member of the walking along side your bike brigade. These things are not light and you don't look nearly as cool.

Since I just became the owner, and PO only had it three months or so, and conisdering what I found in the brake calipers, a good cleaning of the fuel system can't be a bad thing. Might even buy some tubing and replace some 30 year old tubes while I am at it. The "might as wells" just keep on coming.

[boyat68]

DGXSER:

I am with you. It has been in the mid 20s at night around here and not much more than 50 for the past two weeks so I have not started the bike as I had intended to do. I have promised myself that I was going to start the bike every week but... Oh darn, I am going to go right out and do the deed now. I spent a month cleaning the tank and rebuilding the carbs as well as two new petcocks. It would be a shame on me if I let them go to pot again.

[trbig]

"Honestly, I think the octy gets ditched because it is misunderstood."

Or that it makes the bike look cluttered on that side and is a PITA when you're pulling and installing carbs several times.

Seriously.. it is supposed to help, but ends up being the problem so often, that I have decided that it's just not worth it to me to have that THIRD insurance policy. Others like it. I understand it... still don't like them though.

Tod

[TopCatGr58]

Personally, I would not run the petcocks in prime all the time. As I understand it the prime port draws from the bottom of the tank, same as running in reserve all the time. This would end up sucking junk into the carbs or water or whatnot.

I ditched mine years ago due to corrosion, and didn't want to put $$ into a part that I thought was rather redundant! I think that running on Prime....after having thoroughly cleaned out my gastank helps keep the crud from forming in the first place, since it's being flushed thru the system instead of allowing it to collect in the bottom, and gets trapped by the inline filters(a must anyways). I may have had my petcocks mounted backwards, but my ON wouldn't flow. BUT the only reason you're having to use PRIME right now is because the OCTY is still INLINE, and the PRIME bypasses it. Fuel will flow thru the rear petcock PORT in the ON position just like normal, and will be flowing from the UPPER petcock inlet. The only thing is that if you want to have RESERVE available, you'll need to "Y" the petcock outlets instead of just capping off one. The Special petcocks are gravity flow/feed only, no vacuum valve.

SO...you still have the OFF function, and you can feed from the upper inlet ports if you're worried about tank dreges, but with the lines "Y"d, you can also have your reserve function, and still remove the OCTY!
T.C.

[Ken Talbot]

Ok, As previously posted, my 81 special runs great with petcock in prime, but dies when in ON, diagnosis is that the Octy is probably at fault.

Could be that, or could be that a PO had the petcocks apart and mixed up the plates. I.e., the petcock may not actually be flowing fuel to the octy at all. Easy to check by taking the hoses off, putting a couple of clear short hoses on, put the hoses into a catch tin, and test the lever action to see what is really happening, when fuel flows, where it comes from.

[Ivan]

"Honestly, I think the octy gets ditched because it is misunderstood."

Or that it makes the bike look cluttered on that side and is a PITA when you're pulling and installing carbs several times.

Seriously.. it is supposed to help, but ends up being the problem so often, that I have decided that it's just not worth it to me to have that THIRD insurance policy. Others like it. I understand it... still don't like them though.

Tod

In case no one has figured it out, Tod doesn't like the octy. It is probably worth noting that his bike is clean enough that the cluttered part stands out from quite a distance. Now, if his bike were ratty lookin' like mine, it wouldn't be such an issue.

[DGXSER]

The deed is done

I got the chance to do some investigation tonight. The petcocks worked perfectly. The OCTY worked, but leaks. It also appears that the vacuum line is to short and is pinched off as installed, therefore no fuel flow. What I also found is that the output from the PRIME position goes into a T, the flow from the OCTY also goes into that T and that output goes to the carbs. I also found that one of my fuel lines from the ON side of the petcock had a leak in it, so overall, I had a leaky fuel system on the ON side, and a lack of vacuum to the OCTY.

My resolution, for now is to remove the OCTY, plug the vac port on #2 intake plenum, and connect the two inputs into the T to the PRIME and ON sides of the petcocks. I am pretty diligent about turning the fuel off at every stop, so I feel comfortable that this will pose no major additional safety concerns.

My questions, 1. Did the original installation use hose clamps? 2. Are those Ts original equipment?

Question on Manuals - What are the thoughts on using the Clymers, vs the manufacturers manual and the CD or online file downloads?

As always appreciate the input. Perhaps I will rebuild the OCTY and reinstall some day, but for now this seems like a good functioning system.

[bikerphil]

The original set-up is those wire squeeze type clamps with the plastic T's. It's a good idea to add in line fuel filters. Clymers manual is OK, but the factory manual is better. Don't know about the online ones.

[fredintoon]

Running on prime

Hi DGXSER,
Dunno if the Special's prime connection runs off the main or off the reserve.
If the latter, you have no reserve and that's one heavy pig to push. Yes you have a red low fuel warning light but what if you don't notice it or if it's busted.
What I did before I switched to a Standard tank and it's vacuum taps (my octopus was ditched several POs ago) was to blank off the prime spigot on each tap, connect the rightside fuel tap spigot to the leftside inter-carb tee and vice versa to better fit an in-line filter in each line. Just remember to turn both taps gas on and off as required. If someone with better search skills than mine would post the link to the octopus hose diagram you can see there's at least eight hoses needed to hook the thing up. That the octopus needs all those hoses tells me it's too complicated to be reliable.

[DGXSER]

Well I took the time to make a really cool cad schematic diagram of the way my fuel system was setup and the way I rerouted things. Unfortunately, I can not find the right way to get a PDF file to show up on here, sooooo....

I found that my Reserve line runs through the ON petcock port, the PRIME is the only thing running through that port. As to PRIME running from the lower inlet and therefore using the "reserve" fuel, I have not tested that one yet, maybe I will after I run enough fuel out that I can drain my tank into my gas can. A couple more days in the mid to upper 40s can't be that far off.

I found a small fuel filter made by B&S for lawn mowers, anyone tried those on their bike? Any success or horror stories? Also like the clear yellow tubing they sell for lawn mower fuel line. Seems a little more pliable than the black rubbber on mine now.

[tarzan]

Be careful selecting fuel line.A lot of the cheap stuff will kink when routing it around stuff.A real PITA when your rollin along ,smile on your face ,not a care in the world then your bike starts running on two cyl.You check to make sure your not running out of gas ,no its got plenty.Maybe a pickup coil,no thats not it.Damn what is it.Your scratching your head and spend all this time then find out ,doh,a kinked line.....(could it be form experience)hmmm