Testing the octy.

[Gyrogearloose]

Ah....common knowledge says pull the fuel lines from the petcocks, and no fuel should flow. OK. Then says, pull the vacuum line from the octy, put a vacuum to the octy (your face), and fuel should then flow. Ah....flow from where?...the fuel lines you just snatched from the petcocks?...or the petcocks themselves?...or your ears (heh). Please, just wondering if the lines should flow fuel or the petcocks? I expected fuel from the petcocks, and was surprised when I got squirted from side by a hose. Thanks for setting me straight.

[natemoen]

Well to start, if you have the octy I will assume you are dealing with special petcocks as well (if you have standard petcocks correct me cause it makes a difference).

The special petcocks are completely manual. You turn them to on, reserve, or prime, gas will flow vacuum or not, doesn't matter. The octy is the only vacuum controlled part in the fuel system. The octy has 2 fuel in nipples and 2 fuel out nipples. The rear 2 nipples on the petcocks connect to the 2 fuel in nipples on the octy. Now when you turn the petcocks on the octy stops the fuel flow unless there is a vacuum source sucking on the vacuum nipple on the octy. If there is vacuum then fuel will flow out of the other 2 nipples on the octy.

The front 2 nipples on the petcocks should only flow fuel on prime (If the rear nipples flow on prime then the petcocks on on the wrong aide is the tank). Those 2 nipples get Tee'ed into the fuel line coming from the octy out nipples going down to the carbs.

[Gyrogearloose]

Thanks natemoen, it helped me understand how this octy works. Sometimes I need things put in PLAIN terms before it clicks. Ha. Yes, I do have an 80'
Special, and have changed oil twice because of fuel contamination. Now, prior to finding and fixing the problem, I am turning the petcocks off each time I shut the engine off; I think the octy works like it should. I guess maybe I should look at the petcocks....or needles and seats...or, or.....

[BA80]

The prime side (front petcock nipples) must be leaking if the octy is working properly. Those run into a T in the fuel line that bypasses the octy all together.

However, if your carbs ar leaking fuel into the oil you also have a needle valve/float adjustment problem that needs to be addressed. If the carbs are working right they won't leak anyway.

[Gyrogearloose]

Thanks BA80, at least I'll know where to start. I'll do petcocks, then on to the carbs. I'll put them on my test stand; clear hoses attached to float bowls to sync the float levels, and from there I should be able to spot the leaky needle valve. Boy, am i having a hard time finding hose barbs of the 8/1 mm type to screw into the bowls. So far, I'm using a bored out nylon bolt that I ground off the threads (standard), and then cut my own 8mm-1 with a machinist's die, but after a few applications, it starts to leak (no shoulder to mate with the bowl). Any suggestions to finding a suitable hose barb? There's hardly enough nipple on a grease fitting to seal using a hose clamp, but I'll admit, I haven't tried it yet. thanks all. Boy, I will be happy when I get the fuel system working again and I don't have to go through another oil change....or turn off the petcocks each time I stop.

[Rasputin]

You could get a grease zerk and drill out the ball and spring. It would make a good hose barb for what you are doing.

[fredintoon]

Yes, I do have an 80'
Special, and have changed oil twice because of fuel contamination. Now, prior to finding and fixing the problem, I am turning the petcocks off each time I shut the engine off; I think the octy works like it should. I guess maybe I should look at the petcocks....or needles and seats...or, or.....

Hi Geno,
IMHO the best use of the octy is to demonstrate the power of your pitching arm as you fire the thing into the bush.
If you look at the octy's hyper-complifexed fuel & vacuum line set up you can see it's an accident just waiting to happen.
Plug the taps' PRIME spigots, run one hose to the 1&2 carb tee & t'other to 3&4 tee to use 2 lines instead of 8.
Remember to turn the gas on & off like Grandpa had to.
But that's a side issue, some have lived with an octy for years with no problems.
As you say, it's the needles & seats that have to be fixed. Turning the taps to OFF when you park should stop gas getting into the oil because
the needles can't ooze if the gas is shut off but when you turn the gas on to ride it won't stop the engine running rich as the carbs over-fill, eh?