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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Question for Petcock Guru's /cgi-bin/YaBB.pl?num=1218515903 Message started by Digger on 08/11/08 at 21:38:23 |
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Title: Question for Petcock Guru's Post by Digger on 08/11/08 at 21:38:23 I've not yet had the petcock apart on my bike (see signature). However, a while back, I developed what appeared to be a diaphragm leak that was letting gas into the petcock vacuum line, thus making the bike run rich intermittently. Luckily, Serowbot diagnosed that one for me. Well, I then disconnected the vacuum line from the petcock, plugged the vacuum port at the petcock and then plugged the top part of the vacuum line. The bike's been running great ever since. When I shut the engine off, I position the petcock to ON. Before I start the engine, I position the petcock to PRI. I realize that I'm essentially running on RES at all times, but I want to emphasize two things: This is not a problem for me, the way I ride the bike, and I do not consider having to reposition the petcock all the time an inconvenience. As an old-school biker, this is "normal ops" for me. As a matter of fact, I find myself wanting the shut my Gold Wing's non-existent petcock off when I shut the engine down on that bike.....and it has fuel injection! ;D Are you still with me? Here's my question: I realize I should either do the manual petcock mod, or buy a new petcock. However, is there any way the petcock could leak gas into the petcock fuel line when the petcock is set to ON and there is no vacuum being applied to the petcock vacuum port? If gas can't leak out under those conditions, I see no need to do the manual petcock mod. I can happily continue on doing what I'm doing (remember, having a RES capability is not important to me). However, like I said earlier, I have no way of knowing this as I've never had one of these petcocks apart. I do, however, plan to remove the petcock vacuum line altogether and plug the intake manifold vacuum port itself. TIA! |
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Title: Re: Question for Petcock Guru's Post by serowbot on 08/11/08 at 22:08:30 Not 100% sure, but I don't think it can leak. If you really don't want a reserve, I guess you're o.k. It's not that hard to do the convert though, if you change your mind or have a problem later. When you block off the vac line permanent, use a screw with a dab of epoxy or something on it, not just a rubber cap. Mine rotted away, so I sealed it up good. Serowbot |
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Title: Re: Question for Petcock Guru's Post by verslagen1 on 08/11/08 at 22:54:09 Yes, If the diaphram has a hole in it then it will leak, it doesn't need vacuum to do that. 100% sure. The diaphram is constructed of a thin rubber sheet, backed up with a plastic washer and preloaded with a metal leaf spring and a compression spring. This assy has a plunger on the gas side with an o-ring to shut off the gas. Guess what? this area loads up with sediment and corrosion. Enough sediment and white gas boogers and it's going to hold the valve open. If you converted the petcock to manual, what you could do is replace the diaphram assy with a rubber sheet. Then you wouldn't need to worry about a leak. You guys with balky engines at speed... try tightening up the four screws on the back of the petcock. It's possible the vacuum leak is there. |
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Title: Re: Question for Petcock Guru's Post by ls650v on 08/12/08 at 09:22:11 I gave up on my petcock several years ago, removed the vacuum line, and capped the the carb and petcock vacuum ports. Used the bike this way with no ill effects. This past fall, when preparing my bike for winter storage, I pulled the drain plug on the carb float bowl to drain the gas. After filling a small can with gas and not seeing the fuel flow stop, I moved the petcock from On to Prime and then back to On to see if the fuel flow would stop. It did not stop, so just for grins I removed the cap on the petcock vacuum port to see what would happen. The fuel flow stopped, WTF??. Now, instead of a cap, I have attached a hose routed down below the bike, kind of like the vent line on the battery. Everything seems to be working ok for now. I cannot explain why removing the cap from the petcock vacuum port stopped the fuel flow. |
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Title: Re: Question for Petcock Guru's Post by verslagen1 on 08/12/08 at 11:37:54 76692C2F2A6C1A0 wrote:
Apparently your diaphram is whole and you developed abit of vacuum under you capped port keeping the gas on. The problem of 'venting' the cap as you've done, when the diaphram does fail, you'll leave a trail of gas. |
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Title: Re: Question for Petcock Guru's Post by Digger on 08/12/08 at 21:52:27 392A3D3C232E282A217E4F0 wrote:
Ver, Thanks for the info. So, Lazy Man (me) could just take out the four screws on the back of the petcock and replace the diaphragm with a flat Nitrile rubber sheet and bolt 'er back up? This way, I'd not have to remove the petcock from the tank. It's not leaking there now and I see no need to fool with that seal unless I have to. TIA! |
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Title: Re: Question for Petcock Guru's Post by verslagen1 on 08/12/08 at 22:45:07 143937373522500 wrote:
Well you lazy b'tard, at least take the tank off the bike! ;D And take the time to clean out the sand that might be in there. I've thinking of adding a tour tank on the bars. And I'm thinking of converting the petcock to manual. Corking up the vac tap on the carb. take out the diaphram, replace it with a open gasket. And use the vac tap on the back of the petcock to feed in the tour tank. |
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Title: Re: Question for Petcock Guru's Post by serowbot on 08/13/08 at 01:21:50 6D7E6968777A7C7E752A1B0 wrote:
That sounds really trick, but...where's off?... ...actually, I've done the pet-convert, 2 years ago, and I never turn the gas off. I know...if the float needle fails, gas will pour, but I've never had that happen in over 30 years...I like the idea really,... you can go right into the open vac port!...never would have thought of it....If you found a mounting place, higher than the petc0ck, but lower than the top of the gas tank, might it fill right from the tank?...you'd need to vent it. Sorry if this is a highjack.... |
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Title: Re: Question for Petcock Guru's Post by ls650v on 08/13/08 at 03:39:06 7F6C7B7A65686E6C6738090 wrote:
I will take my chances. How many people on the forum have reported gas pouring out of the petcock vacuum port? None that I know of. Better to dump gas on the ground than onto a hot engine. |
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Title: Re: Question for Petcock Guru's Post by verslagen1 on 08/13/08 at 07:22:20 6B7431323771070 wrote:
None because they capped it. And there has been reports of gas dripping into the intake via the vac line. So your decission, your bike. |
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Title: Re: Question for Petcock Guru's Post by verslagen1 on 08/13/08 at 07:24:13 4157405D45505D46320 wrote:
You did plug one of the ports with a set screw didn't you? Off for the tour tank will be a sepparate petcock for it. |
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Title: Re: Question for Petcock Guru's Post by serowbot on 08/13/08 at 07:56:28 Yep, I did,...I was talking about the vac-side spare tank...show us when it's done, o.k.? |
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Title: Re: Question for Petcock Guru's Post by Digger on 08/13/08 at 20:00:19 776473726D6066646F30010 wrote:
Well you lazy b'tard, at least take the tank off the bike! ;D And take the time to clean out the sand that might be in there......[/quote] The tank will already be off, as I will be checking valve clearances and torquing head bolts. I also intend to check the cam chain adjuster on this next maintenance cycle and perhaps install a Verslavy, if required. Now, does anyone know where I can purchase some Nitrile rubber gasket stock? |
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