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Registered
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32 Posts
Discussion Starter #1
on my 1986 vn 750 i have the fuek tap on the tap it has res/on/pri where is the off postion and what does pri mean is this prmary
 

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Old Truck Junkie
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4,133 Posts
pri=prime mine still does not flow in prime unless it has vaccuum applied to the on off hose.
 

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DelmarvaBiker
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15 Posts
Petcock

For what it's worth, after reading what you all wrote, I had to go double check what was written on my petcock. I have Off, On, and Res. Off is off as I can run my carbs dry. On is vacuum controled. And reserve works as it is suppose to when I run out of fuel in the On position. Giving me enough to find a fuel stop to refill. I'm not sure about the Pri as I do not have that on my petcock.
 

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Premium Member
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4,054 Posts
Huh. On my KZ's, PRI was prime, and it would fill the carb bowls without engine running and vacuum. I wonder if someone rebuilt your petcock Niterider? Maybe the 750 PRI needs vacuum. That doesn't make any sense though, at least to me.
 

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Old Truck Junkie
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4,133 Posts
You are right, it makes no sense. I have had the tank off and gone through the positions and none flow gas without the vaccuum being put to the hose. I even had the petcock apart and could not figure it out.
 

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Premium Member
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126 Posts
my 96 has res-on-off.
the other day i put it on off and let it run thinking it would empty out the carbs... it ran for 20 minutes in off and i gave up waiting and put it back to on.

how long should it run in 'off'... or is my 'off' not doing what it says?
 

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Premium Member
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126 Posts
and a secondary question.... i've never liked the vacuum on the petcock, seems like a fix for a problem that didn't exist. whats so hard about flipping the petcock to off when i park. been doing that for 30 years on my other bikes and never had a problem.

is there a direct replacement petcock that i could swap in that does not have the vacuum requirement, just a normal res-on-off position?

i could get rid of some more vacuum lines and not worry about coming out to the bike and finding it in a pool of gas from a broken diaphragm in the petcock. (this seems to be common on new bikes, saw 2 in the parking garage this summer like this, i assume from their vacuum petcocks).
 

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Young Gun
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213 Posts
Check out this thread

...it does not have the vacuum thingy but it has an OFF position... ...This is the information I found in the box:
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- Model: XT200
- ITEM: COCK FUEL
- PART No: 15A-24500-02
---------------------------------------------
it has only one pipe that go to the Carbs, so I used a T to connect it to both carbs, It works perfectly, I thought it wouldn't send enough fuel to both carbs but it does.:motorcycl
 

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Linkmeister Supreme
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7,960 Posts
my 96 has res-on-off.
the other day i put it on off and let it run thinking it would empty out the carbs... it ran for 20 minutes in off and i gave up waiting and put it back to on.

how long should it run in 'off'... or is my 'off' not doing what it says?
The first 3 or 4 model years from `85 to about `88 had petcocks with PRI(me), ON and RES(erve). The PRIME position is supposed to fill the carbs without vacuum being applied. For some reason Niteriders petcock does not allow this to happen.:confused:

I have had the tank off and gone through the positions and none flow gas without the vaccuum being put to the hose. I even had the petcock apart and could not figure it out. - Niterider
All later vn750 models from 1989- 2006 have a petcock with OFF-ON- RES(erve) positions. Vacuum must be applied to the middle nipple to get fuel to flow from the 2 end nipples.
 

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Daily rider
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1,043 Posts
my 96 has res-on-off.
the other day i put it on off and let it run thinking it would empty out the carbs... it ran for 20 minutes in off and i gave up waiting and put it back to on.

how long should it run in 'off'... or is my 'off' not doing what it says?
I suspect "Off" is not doing what it says. My '01 had "Off" "On" and "Res", and "Off" would run for a minute or two, then it would die, which is how it is supposed to work - empty the carb bowls, then quit. I have always been in the habit of turning the petcock off when the bike is parked. That is until my current bike, which has EFI, and no petcock.
 
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