Fuel switch posistions/Fuel shut off switch/Fuel Filter

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Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by BostonRickB » Thu Dec 20, 2012 12:06 am

I have a 2011 patrol and it has a fuel switch with 3 posistions. One for the tank, one for the reserve, and one posistion in the middle, if left in this posistion, I am told, it will drain the tank into the cylinders. What is the purpose for this posistion?
I also added a shut off switch in the main line from the tank to the carbs and I am going to add a fuel filter in the main line also. What the talk on doing that? Thanks!
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by Albuquralque » Thu Dec 20, 2012 12:09 am

It is the prime position. It let's fuel flow out of the tank without the engine running (or vacuum operating the petcock from the left carb). Your cylinders will only fill with fuel if left in prime and one of your carb float needles is stuck open.

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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by Albuquralque » Thu Dec 20, 2012 12:12 am

It is mainly used when you have to balance your carbs with a twinmax or harmonizer. These devices use vacuum from both carbs to operate. This means you have to disconnect the petcock vacuum line to connect the twinmax or harmonizer.

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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by gobium » Thu Dec 20, 2012 12:13 am

On your gas petcock, there are 3 positions, prime, reserve and on.
DONOT leave it on prime beacuse gas might migrate into cylinders and engine.
Always kick your bike before use starter, this is to make sure engine is not hydro lock.

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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by MartyL » Thu Dec 20, 2012 9:05 am

Fuel filters come up often. Factory got rid of them as petcock screen they felt was good enough. If you have paint in the filler neck of your gas tank then it may be a good idea to have the filter as the paint flakes off and could possibly by pass the petcock screen. I believe the 2012 model now coat their filler necks of the tank with zinc.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by GHGoodwin » Thu Dec 20, 2012 11:51 am

Get rid of that thing. Yamaha petcock bolts right on. Only three positions on/off/reserve. You'll have to shorten the intake tube to the same height as the stock one by removing the screen tube and cutting off with fine hacksaw or tubing cutter. Ream entrance hole and put screen tube back on. Total changeout in about 20 min. Part # 2GU-24500-02-00. Some gas spillage inevitable.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by BostonRickB » Thu Dec 20, 2012 1:33 pm

So what is the engineers purpose for the prime posistion? I gather it is for when they balence the carbs? Is that correct. Are there any other times when this posistion is needed? I have not seen a twinmax in work so I assume the engine is off when this happens since you will use the gravity to move the fuel into the carbs?
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by rivers » Thu Dec 20, 2012 3:20 pm

You might need Prime occasionally for a few seconds to fill the float bowels if the bike has been sitting for a long time and the carbs have drained. Otherwise leave it in the ON position. There's usually enough fuel in the bowls to get the bike lit. Once running vacuum opens the petcock diaphragm to restore fuel flow into the carbs. I haven't had issues with the Ural petcock but have on other bikes w/vacuum petcock diaphragm leaking and getting fuel into the vacuum hose causing serious rich running besides rotting the vac hose which in turn dribbles fuel everywhere when you shut down. If you don't feel warm-n-fuzzy with the vac tap there's been discussions here regarding a Yamaha conventional tap replacement. When E10 finally eats mine I'll go with manual but so far so good even on the 06.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by WEGUNTER » Thu Dec 20, 2012 4:16 pm

I have an 06 Ural too and have had zero problems with the vacumn petcock. Always leave the it in the on position. Only time I have put it on prime was when I ran out of gas once and also when I am working on the carbs and need to drain the floats. Think the inline filters are pretty useless other than giving you a good feeling.

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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by Ivan Rider » Mon Dec 24, 2012 1:33 am

BostonRickB wrote:So what is the engineers purpose for the prime posistion? I gather it is for when they balence the carbs? Is that correct. Are there any other times when this posistion is needed? I have not seen a twinmax in work so I assume the engine is off when this happens since you will use the gravity to move the fuel into the carbs?
You use Prime position to fill the carbs after prolonged sitting or carb draining so it gets fuel quicker without running the starter long enough to make vaccum. It's also used to drain the fuel tank for removal. That said I usually replace the vaccum ones with manual ones as I have had the engine starve for fuel on long hills under load due to lack of vaccum. The down side of the manual petcock is you Must remember to turn it off when you stop. Ural went to the vaccum one to make it idiot proof. They had a lot of hydrolicked engines with people not turning off the manual petcocks.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by BostonRickB » Mon Dec 24, 2012 12:18 pm

I, pinched off the fule line, opend the allens on the bowls and drained them. This spring I figure I will have to switch to prime, open the allens again and unpinch the fuel lines. Once I get the fuel flowing out the bowl, I will close the allens and switch the petcock to the tank possision and be ready to start it up. Is that correct?
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by Albuquralque » Mon Dec 24, 2012 1:07 pm

BostonRickB wrote:I, pinched off the fule line, opend the allens on the bowls and drained them. This spring I figure I will have to switch to prime, open the allens again and unpinch the fuel lines. Once I get the fuel flowing out the bowl, I will close the allens and switch the petcock to the tank possision and be ready to start it up. Is that correct?

Sounds correct.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by BostonRickB » Wed Apr 03, 2013 8:34 pm

Ok shut off works fine. I added a fuel filter too and no problems. I was a bit worried I was restricting the fuel flow too much but engine responds fine with inline filter. I put the filter before the split to each carb instead of a filter before each carb. Works for me.
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by cdscoot » Wed Apr 03, 2013 9:52 pm

There should be no need to pinch the fuel lines on the vacuum petcock. If the engine is not running there is no vacuum to open the petcock valve and it should not leak. So you don't have to do any thing! I teed into the vacuum line and run it to both carbs. This way there is no excuse to not have vacuum. My bike is always trying excuses ! :P The vacuum valve has always worked for me, but otherers think they have had problems . :roll: I doon't need extra filters either .
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Re: Fuel switch posistions/Fuel shut off switch/Fuel Filter

Post by MrMudder » Mon Jun 12, 2017 8:46 pm

Ivan Rider wrote: You use Prime position to fill the carbs after prolonged sitting or carb draining so it gets fuel quicker without running the starter long enough to make vaccum. It's also used to drain the fuel tank for removal. That said I usually replace the vaccum ones with manual ones as I have had the engine starve for fuel on long hills under load due to lack of vaccum. The down side of the manual petcock is you Must remember to turn it off when you stop. Ural went to the vaccum one to make it idiot proof. They had a lot of hydrolicked engines with people not turning off the manual petcocks.
I like the idea of the yamaha petcock replacement but on my 2002 I have the Kp33 petcock that is treaded on to the gas tank with the 2 way nut, has anyone found a generic replacement for that? If so what is it, thanks.
Last edited by MrMudder on Mon Jun 12, 2017 9:01 pm, edited 1 time in total.
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