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Question: Have you had any issues with the stock petcock?

No        no issues so far on my bike
Yes          petcock issues took place
Fixed   I fixed hoses/rebuilt petcock
Replaced          I went with a Raptor
My bike was less 10 years old
My bike was 10 to 20 years old
My bike was over 20 years old
Overheating damage done to bike


« Last Modified by: Oldfeller--FSO on: 10/11/10 at 08:32:46 »

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Issues with stock vacuum actuated petcock (Read 1272 times)
Routy
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Re: Issues with stock vacuum actuated petcock
Reply #15 - 10/12/10 at 07:39:38
 
Thats the answer IMO.
I will always defend the vacuum petcock. It is after all, a saftey feature that I believe worth some maintenence every few years if needed.
I went down on gravel a while back,.....took me a few mintutes to regroup,....after a couple seconds the engine quit running, and I didn't have gasoline running all over hot exhaust either.
6,000 miles....no problem yet. If and when it does give me a problem, I will fix it, just as I would any other problem caused by deterioration. In the meantime, "prime" was put there for a reason.
justin_o_guy2 wrote on 10/12/10 at 04:13:20:
I guess what Ill do is try to remember to put it on prime if Im gonna be askin for max fuel delivery.

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Rich
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Routy
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Re: Issues with stock vacuum actuated petcock
Reply #16 - 10/12/10 at 07:56:38
 
Quote:
THEORY
Have we just explained the (not so rare) sudden onset of oil consumption issues, the more occasional piston/rings suddenly getting mangled up and the very rare holed piston and popped off valve tulip head?
------------------------------------------------------------------------
Heres another theory..........
Once the fuel level gets low enough to start to cause lean/heat damage, the engine is coughing and sputtering, which can be define as "the fire is out!" and where there ain't no fire, there ain't no heat, and where there ain't no heat, there ain't no damage ! Shocked Roll Eyes

Hey, one theory is as good as tnother Wink

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Rich
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bill67
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Re: Issues with stock vacuum actuated petcock
Reply #17 - 10/12/10 at 08:20:46
 
Routy wrote on 10/12/10 at 07:39:38:
Thats the answer IMO.
I will always defend the vacuum petcock. It is after all, a saftey feature that I believe worth some maintenence every few years if needed.
I went down on gravel a while back,.....took me a few mintutes to regroup,....after a couple seconds the engine quit running, and I didn't have gasoline running all over hot exhaust either.
6,000 miles....no problem yet. If and when it does give me a problem, I will fix it, just as I would any other problem caused by deterioration. In the meantime, "prime" was put there for a reason.
justin_o_guy2 wrote on 10/12/10 at 04:13:20:
I guess what Ill do is try to remember to put it on prime if Im gonna be askin for max fuel delivery.


+1 If mine went bad I would replace it with another stock one,Never had one go bad in 39 years.
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william h krumpen
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Re: Issues with stock vacuum actuated petcock
Reply #18 - 10/12/10 at 09:06:14
 
Routy wrote on 10/12/10 at 07:56:38:
Heres another theory..........
Once the fuel level gets low enough to start to cause lean/heat damage, the engine is coughing and sputtering, which can be define as "the fire is out!" and where there ain't no fire, there ain't no heat, and where there ain't no heat, there ain't no damage ! Shocked Roll Eyes

Being a long time wicker in a environment that allows mandates higher speeds, I perhaps have more opertunity to experience a sputter due to a low bowl level more than most.  So yes, it does happen and the 1st impulse is to flip it to prime.
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ralfyguy
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Re: Issues with stock vacuum actuated petcock
Reply #19 - 10/12/10 at 09:18:21
 
I ran it 30 miles the other day with passenger, mostly on full throttle the whole time. I didn't get a stutter or anything. But the issue is that the handle is so hard to turn anymore, it almost requires a pair of pliers. I am afraid it will break off soon. As soon as I get in some moolah I will order me a new one. Mine is an '06 btw.
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bill67
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Re: Issues with stock vacuum actuated petcock
Reply #20 - 10/12/10 at 09:39:15
 
Their all hard to turn you should turn it once in a while or it will get harder.
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william h krumpen
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Re: Issues with stock vacuum actuated petcock
Reply #21 - 10/12/10 at 10:02:37
 

Routy,

If the bowl just ran quickly empty then your "fire is out, no heat" theory would work out.  However, if because of the low input rate the bowl runs lower and lower and lower fuel level for a goodly period of time before the sputter stop then you ran a hotter engine due to an unusually lean fuel mix during that period of time.

Piston rings sticking and minor pistion/cylinder scuffing are something we see occasionally and "sudden onset" of oil consumption is noted as a common enough thing with these engines.  Give them 15,000-20,000 miles and we seem to pick that up on the majority of these engines.  But we all seem to note it "just starts one day" and "it happens when you go faster".


=======================


Here's what I am pulling out of the polling data we have gotten so far.

About half of us ride in a fashion that allows the petcock to show itself.
(yes, if you putt around you may never see the issue)

It isn't a time related (ditto mileage related) thing so much as an inherent to the design thing.  This surprised me.  I expected age and deterioration to be the cause of onset, but all the newer bikes showing up in the poll say otherwise.

It is a bigger issue (number-wise) than I thought it would be.


======================


This causes the question "Does 10% Ethanol gas play in this effect?"  We are running something for fuel these days that is 1) less efficient (requires a higher gas flow rate at high speeds) and 2) something that may affect the flexibility of the diaphragm over time.

The bike wasn't designed or spec'd for ethanol gas -- it didn't exist back then.

The petcock "getting too stiff to turn" is another indication of something making the original petcock design get cranky and start to malfunction.  The Raptors turn fairly easily but then again you turn them on and off every day.


We have a petcock issue, it affects about half of us ...




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ralfyguy
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Re: Issues with stock vacuum actuated petcock
Reply #22 - 10/12/10 at 10:28:21
 
Another thing that I can't explain: Back almost three years ago when I bought the bike used, whenever I ran outta gas and switched to reserve and then went to gas up, it took about exactly 2 gallons to fill up. This equaled about 100 miles. Now I run outta gas after about 80 miles, and whenever I fill it up it only takes 1.8 gallons. Had the whole thing out several times and disassembled, put it back together. No dirt or anything in there, but I still run out of gas after 1.8 gallons/80 miles. I put a new vacuum hose on it, and didn't make a difference. I suspect that the diaphragm is too stiff for the vacuum as I don't have any gas in the vacuum line either. Also back in the day when I ran outta gas it was a more sudden shut off, the engine just cut out completely all the sudden. Now it is more like starting to stumble a little at a time and getting more and more, worse when the throttle is opened more. Would still idle, but not accelerate hard.

What do you think?
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Re: Issues with stock vacuum actuated petcock
Reply #23 - 10/12/10 at 10:34:39
 

Got me, I dunno.

Raptors "jest work", they cut out all the symptom confusion crap associated with the vacuum actuated petcock system
(which can flat drive you nuts trying to figure out what's going on sometimes).

I am content flipping a manual petcock on and off, but I understand some folks being reluctant to lose the automatic cut off feature.  They want the reassurance.

We have no guarantee of having enough full open throttle vacuum to move some other vacuum type valve reliably (lack of suck at high speed IS the root issue with the existing petcock after all) so for those that must have a cut off I give you the $20-$22 relatively low cost 12 volt actuated electrical shut off valve ...

http://www.opentip.com/product_info.php?ref=8955&products_id=1747898&affiliat...



These things also get used in RV's and they have some higher capacity models at about the same price, so look here too and go down to the bottom of the page to see the rest of them.

http://www.twinsrecreation.com/br79-afc11112.html
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ralfyguy
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Re: Issues with stock vacuum actuated petcock
Reply #24 - 10/12/10 at 10:48:21
 
That's a nice idea. If I still had my machinist shop, I would machine a flange to bolt that valve on the tank and wire it up. NICE!
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Re: Issues with stock vacuum actuated petcock
Reply #25 - 10/12/10 at 11:00:37
 

Those are 1/8 standard nipple fittings, so it is small enough to be supported by the fuel line loop and simply tucked away under the tank/seat junction.  Steal the "on" power from just about any constantly on electrical function.  It draws .75 of one amp for power so it wouldn't stress anything or require you to re-fuse the function you stole the power from.

What's funny to me is the stock vac petcock from Suzuki costs a lot more than a raptor and one of these ...

Cheesy
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bill67
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Re: Issues with stock vacuum actuated petcock
Reply #26 - 10/12/10 at 11:17:08
 
I love my pet thingy just the way it is Grin
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william h krumpen
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Re: Issues with stock vacuum actuated petcock
Reply #27 - 10/12/10 at 11:24:18
 
Seeing as the failure rate is nearly 50% within the first ten years, virtually certain eventually,... and failure causes a massive fuel leak,... and this fuel leak occurs while you are running...
I say, it's not a very safe, safety feature... Huh...

If I'm gonna' have a fuel leak,...
I'd rather have it when I go down, or parked,... than while I'm rollin'...
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Ludicrous Speed !... ... Huh...
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Re: Issues with stock vacuum actuated petcock
Reply #28 - 10/12/10 at 12:34:32
 

Splitting the diaphragm and puking lots of fuel down the vac hose is only one  (1)  of the many many petcock failure modes.

(yeah, it's the flashiest of the lot as having raw gas puke all over your airbox certainly gets your attention, especially if you have a loose spark taking a hard corner, etc).  

There are MANY more failure modes associated with low fuel flow, jest about half the newbie "it won't run right" questions we get wind up having something to do with an ill petcock.  

I wonder how many jets got changed when the issue was really low bowl fuel levels ....
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Re: Issues with stock vacuum actuated petcock
Reply #29 - 10/12/10 at 19:28:38
 
Oldfeller, I think I'd be a little careful with the poll numbers. As of this writing the poll shows 83 votes, and per your request those who voted YES voted more than once. The forum has over 13000 members, most of whom are presumably inactive. 83 votes from 13000 members isn't a very high percentage reporting, which in itself may make the numbers suspect. And if this group is like many others, only those who have problems feel strongly enough to even vote.

Also, the electric fuel control valve looks like a good idea, except there might be a problem with setting up a Reserve system. One problem is that the fuel tank has only one hole. Another is that in a get-off the valve isn't likely to be shut off unless there is also a bank angle sensor.

10% ethanol gas has existed at least since the late '70s, when they called it "gasohol." I have used it since 1978, at least. The first vacuum petcock I owned was on a 1983 Suzuki Tempter, which ran with no petcock troubles for the 14000 miles I owned it (using gasohol a good part of the time). The Savage hit the road in 1985, somewhat after gasohol came into use. I have to assume Suzuki knew about it, and I would presume they designed their machinery to accept it.
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Eschew obfuscation.

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