Fuel cock (kinda dumb name for it) fuel tap is more polite.

[Revvy Kevvy]

Tonight I was working on the tank. Its actually the first time I have even looked at it because it came unattached in a separate box. I found a funny three position valve and I understand there is a vacuum from the engine goes into it.

I understand from looking at manuals and stuff that it connects to the rubber doobiewacki thinghi that is between the carburetta and the inlet valves. I think we are calling them boots.

As far as I can tell the vacuum opens the fuel cock but it has three postions...

PRI....prime?? does this mean it can run all the time without the vacuum...like for filling the carburetta bowls for example. Can I just turn it to prime and leave it here.??

On...is on, I guess it on when the vacuum is running. Engine stops providing vacuum it automatically off?

RES is reserve, pulls from one of the wings of the tank when you switch it over but also needs vacuum?

I never saw this before, all other bikes I had only had off/res/main....

How good are they? I opened the fuel cock up and it had a filter in it and a rubber diaphram to turn it on and off using the vacuum. I dont feel very trusting of this idea.

Actually I am fully sus of it, it feels like something that can be the root of all evil.

 

[Revvy Kevvy]

Ok, attached a vacuum pump to it to test is as I had no engine running at the time and it works exactally as I described.

Prime, its on all the time, not too sure from what wing but I guess not reserve.
On, is only on when the vacuum is sucking
reserve is only on also when the vacuum is sucking.

I will just leave it on prime, I not too sure the point of the other two unless you are scared of a fuel leak.

 

[CaptChrome]

I got a manual fuel tap myself. One less thing to troubleshoot when the bike doesn't want to run - in my opinion.

 

[Revvy Kevvy]

I got a manual fuel tap myself. One less thing to troubleshoot when the bike doesn't want to run - in my opinion.

I have come to the conclusion this vacuum fuel cock is a un-necessarily complex tap.

 

[kebabs]

I have come to the conclusion this vacuum fuel cock is a un-necessarily complex tap.

the vacum isn't needed.but imagine belting down the high way and a fuel line comes loose.fuel will keep flowing bang

 

[kebabs]

the vacum isn't needed.but imagine belting down the high way and a fuel line comes loose.fuel will keep flowing bang

my original fuel tap was unfixable. got a aftermarket one.it works great with the vacum .no issues

 

[dchart]

Did you really say "polite"?

 

[MrOpenRoad]

Ok, attached a vacuum pump to it to test is as I had no engine running at the time and it works exactally as I described.

Prime, its on all the time, not too sure from what wing but I guess not reserve.
On, is only on when the vacuum is sucking
reserve is only on also when the vacuum is sucking.

I will just leave it on prime, I not too sure the point of the other two unless you are scared of a fuel leak.

"ON" is your standard setting, vacuum pulls fuel into the carbs when the bike is running. This is what you should be in the majority of the time. "RES" is reserve, when the bike begins to run out of fuel in the "ON" setting you swap to reserve, which opens up another fuel route and accesses the lower reserve volume of the tank which "ON" cannot reach. "RES" is your warning to get to a gas station ASAP. "PRIME" is like a sink faucet, when turned to PRIME the tank will continuously poor fuel. PRIME is used for either draining out the tank to empty it OR to quickly fill the carb bowls with fuel if they are empty, such as after a rebuild. Understand this, DO NOT leave your bike in PRIME. Over time your carb bowls WILL overflow, potentially overflowing into and flooding your engine and that is a can of worms that can lead to a lot of damage.

So, moral, leave the bike in ON. Switch to RESERVE when you run low on gas. PRIME is only for emptying or the quick filling of the carbs ("priming" the carbs").

 

[Revvy Kevvy]

Got it Mr open road...to On they stay and they seem to work quite well in this position. Tomorrow is my iTraffik test....then on the road she can go and I will be able to test this more fully.

 

[Revvy Kevvy]

Did you really say "polite"?

I try to stay polite when I can.