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Discussion Starter #1
Probably a stupid question, but this is my first bike with a petcock.
Do I really have to turn it off and on after and before each ride, or is it OK to just leave it on all the time? It has on, off, and reserve positions. I only use the bike at weekends.
Thanks.
 

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If the petcock is working properly, with no leakage, there is no reason to turn off for shorter periods of inactivity. if you were gonna leave the bike for a month, I would turn off. a week should be just fine.

Just to let you know, the petcock has a vacuum operated valve in it to shut off fuel when engine is not running. the off position is a manual position for turning off the fuel if needed
 

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The old biker in me says it’s a good idea to get in the habit of turning it off after a ride, and of course remembering to turn it back on before you start it.

These bikes are getting old now, And it’s not uncommon to walk into your garage and find a pool of gasoline under it. It might be a small chance, but as a rider you learn not to take chances ;)
 

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This was my first bike too, I put the bike in storage for a couple months the first year and did not shut the petcock. The first time I took it back out on the highway oil was coming out any place it could. Not knowing what was going on I took it to a mechanic. That’s how I learned that your gas tank can slowly leak into your engine. So now it’s just habit to shut it when I’m done riding for the day.
 

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I turn mine off when I’m a few streets from home in my subdivision. Then I see if I can make it into garage before I run out of gas.

With some practice I found the optimal spot to turn fuel off and not run out before I’m home.
 

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MY 86 VN750 doesn't have an "OFF" position. It just has On, Reserve, and PRI which I assume is Prime. My bike can't be the only VN750 like that. My prior 86 model years ago was the same..
 

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On prime, the petcock is open without needing vacuum. Good setup actually. Have seen some that would run fine on prime, but not on, probably a bad petcock diaphragm.

Really have to keep an eye on these petcocks, check for a dry vacuum hose on a regular basis. Don't even use a hose clamp on mine, so I can just pop it loose.

The petcock can leak through when set to 'off', if the diaphragm is bad.

edit: With a bad diaphragm, it can leak and fill up the crankcase on any setting, with the engine off. Any gas in that hose goes straight into the front cylinder. Hose should always be dry.
 

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On prime, the petcock is open without needing vacuum. Good setup actually. Have seen some that would run fine on prime, but not on, probably a bad petcock diaphragm.

Really have to keep an eye on these petcocks, check for a dry vacuum hose on a regular basis. Don't even use a hose clamp on mine, so I can just pop it loose.

The petcock can leak through when set to 'off', if the diaphragm is bad.

Good to know about the prime, Spockster. I have found in the winter, when it has been sitting for awhile, and I go to run it for 1\2 hr or so, it fires up quicker in the prime position. However, I do not even have the option to shut it off. Just reserve and on positions, other than the prime. I did inspect my fuel lines the other day. Still soft and flexible surprisingly. Also finally sucked the front brake fluid outta her reservoir. Looked like factory fluid! Sucked it out with a syringe, but didnt touch lever, so no air introduced into line. Filled up with new DOT4 fluid, and bled left side until nice and clear, and then right side until nice and clear. Old stuff dark as used motor oil, lol. New stuff is nice and clear. I can hear it thanking me now! Last night I put on 4 new NGK plastic plug thingys on end of the new plug wires that push onto spark plug. Last fall, I noticed if I touched two of them(the longer two of them), they lit me up like a light bulb! Not sure if it will affect performance or reliability, but will find out soon!
 

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Good to know about the prime, Spockster. I have found in the winter, when it has been sitting for awhile, and I go to run it for 1\2 hr or so, it fires up quicker in the prime position. However, I do not even have the option to shut it off. Just reserve and on positions, other than the prime. I did inspect my fuel lines the other day. Still soft and flexible surprisingly. Also finally sucked the front brake fluid outta her reservoir. Looked like factory fluid! Sucked it out with a syringe, but didnt touch lever, so no air introduced into line. Filled up with new DOT4 fluid, and bled left side until nice and clear, and then right side until nice and clear. Old stuff dark as used motor oil, lol. New stuff is nice and clear. I can hear it thanking me now! Last night I put on 4 new NGK plastic plug thingys on end of the new plug wires that push onto spark plug. Last fall, I noticed if I touched two of them(the longer two of them), they lit me up like a light bulb! Not sure if it will affect performance or reliability, but will find out soon!
The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.
 

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The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.
I got mine from dennis kirk. like $8 total including wires.
 

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On prime, the petcock is open without needing vacuum. Good setup actually. Have seen some that would run fine on prime, but not on, probably a bad petcock diaphragm.

Really have to keep an eye on these petcocks, check for a dry vacuum hose on a regular basis. Don't even use a hose clamp on mine, so I can just pop it loose.

The petcock can leak through when set to 'off', if the diaphragm is bad.

Good to know about the prime, Spockster. I have found in the winter, when it has been sitting for awhile, and I go to run it for 1\2 hr or so, it fires up quicker in the prime position. However, I do not even have the option to shut it off. Just reserve and on positions, other than the prime. I did inspect my fuel lines the other day. Still soft and flexible surprisingly. Also finally sucked the front brake fluid outta her reservoir. Looked like factory fluid! Sucked it out with a syringe, but didnt touch lever, so no air introduced into line. Filled up with new DOT4 fluid, and bled left side until nice and clear, and then right side until nice and clear. Old stuff dark as used motor oil, lol. New stuff is nice and clear. I can hear it thanking me now! Last night I put on 4 new NGK plastic plug thingys on end of the new plug wires that push onto spark plug. Last fall, I noticed if I touched two of them(the longer two of them), they lit me up like a light bulb! Not sure if it will affect performance or reliability, but will find out soon!
The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.
I got mine from dennis kirk. like $8 total including wires.
Wow, Dennis has the best price on those. Lowest on eBay is $14 for one, and most bike sites want $44 for one of the long ones.
 

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The prime lets it fill the carb bowl. With the newer petcock we have to crank-pause-crank-pause-crank-pause , until we get it to fire. Crank makes the petcock open, pause lets the gas fill the carb. Beats cooking the battery and starter.

Right side carb always dries out in about 5-7 days, worse on the sidestand.

Had to change brake fluid on one of my cars last Fall, stuff looked like black coffee, with grounds in it. Totally filthy, original from 2000.

Need the plug boots changed on mine, one is arcing on the throttle cable and at least one other leaks. Clearing up voltage leaks should help your spark and starts. I know mine would bite me, but I can't like electrocution, I jump too hard when shocked, could snap a bone.

Did you get the NGK boots off ebay, or somewhere else? I need to shop.
LOL, Me no likey sparky, not when on my hand. Yes, I bought all 4 NGK boots on Ebay. Cost me about $20 for all 4 with the rubber grommet to seal both ends. Been chilly and rainy again here, so haven't hit the road with them yet. My wires were replaced last fall, so didn't need those.

Also, I always use my side stand when I pull into the garage. I do exactly as you, crank, wait a sec, crank, and it usually fires right up on the front cylinder until right bowl gets fuel. Hate that piston knock sound! It comes out of it quite quickly though once carb gets fuel, then the RPM's climb right up. Too much of a PITA to use center stand every time I drive into garage, knowing it'll be out in a day or two. Ahh yes, the quirks of the mighty VN750. LOL
 

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Wow, Dennis has the best price on those. Lowest on eBay is $14 for one, and most bike sites want $44 for one of the long ones.

I paid between $9-$10 for a pair of each boot on Ebay. Didn't need wires. Changed last fall with wire bought at Napa for a few bucks. Also didn't need to pay shipping on Ebay. I'm thinking Dennis is going to add shipping to that order.
 

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Must be one of those times when I roll snakeyes on eBay, wait a few days and there may be some better listings.

My back hasn't allowed using the centerstand for a couple of years now.

Ya ole Dennis, he likes the shipping charges.

Been a little worried about getting zapped through the throttle, quite a bit of metal in those ISO grips. I would leap right off.
 

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Must be one of those times when I roll snakeyes on eBay, wait a few days and there may be some better listings.
Heres what I got, Spockster:

https://www.ebay.com/itm/NGK-Spark-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

https://www.ebay.com/itm/NGK-Spark-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2648

Be aware only one or two had the NGK logo in white. It didnt bother me, because the long 102 degree ones go all the way into cylinder head anyway, but not a bad deal. I could have complained, but picked my battles.
 

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Must be one of those times when I roll snakeyes on eBay, wait a few days and there may be some better listings.
Heres what I got, Spockster:

https://www.ebay.com/itm/NGK-Spark-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

https://www.ebay.com/itm/NGK-Spark-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2648

Be aware only one or two had the NGK logo in white. It didnt bother me, because the long 102 degree ones go all the way into cylinder head anyway, but not a bad deal. I could have complained, but picked my battles.
Whoa, thanks. Somehow I think using my phone to search may have skewed my results. That's not a bad deal. Beats $44 for one!
 
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