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Roidfingers
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« on: February 17, 2017, 03:19:43 PM » |
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What could be causing my rpms to hang up? When I release the throttle it snaps back to close position but rpms are very slow to return back to idle. I'm having a problem with a possible leak at #5 air cut valve. Could this cause this? Any other thoughts???
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Lyle Laun
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« Reply #1 on: February 17, 2017, 04:00:12 PM » |
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Your air Leak on your intake is causing that
Lyle...
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Get out & Ride !!
97 Red/White Standard dressed as Tourer
98 Black "Rat Rod" Standard
99 Green/Silver Interstate
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Roidfingers
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« Reply #2 on: February 17, 2017, 04:26:41 PM » |
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Specifically the air cut valve?
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gordonv
Member
Posts: 5762
VRCC # 31419
Richmond BC
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« Reply #3 on: February 17, 2017, 05:24:21 PM » |
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I lost my bike before I could fix mine, but he is saying the carb intake tubes into the cylinder head. The O-rings.
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1999 Black with custom paint IS   |
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98valk
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« Reply #4 on: February 17, 2017, 05:30:17 PM » |
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a vacuum leak causes the rpms to hang and then drop.
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C 10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp
"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
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WintrSol
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« Reply #6 on: February 17, 2017, 06:13:19 PM » |
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Any vacuum leak can cause this, and, yes, if the diaphragm in the cut-off valve is failing, it can leak into the vacuum port. A pinhole in the piston diaphragm can also create a vacuum leak.
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98 Honda Valkyrie GL1500CT Tourer
Photo of my FIL Jack, in honor of his WWII service
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Roidfingers
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« Reply #7 on: February 17, 2017, 07:39:09 PM » |
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piston diaghram as the one in the top of the carb? where the large spring is. ? So I guess since I've changed all lines on carbs except air cut valves and piston diaghrams then I should pull carb bank again and slowly go from there?
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Harryc
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« Reply #8 on: February 18, 2017, 03:34:48 AM » |
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The Vacuum slide diaphragms can be removed with the carb bank in place. You'd have to remove the choke linkages on both sides to get to the screws though.
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Roidfingers
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« Reply #9 on: February 18, 2017, 05:02:20 AM » |
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I have ordered some 7mm hose to replace all the hoses on the cut valves. I guess I should check them with my mighty vac also. How do these come off the carbs? Or can they be checked while still attached? Also will pull and inspect the main jet diaphrams. Is there a way to test these? I will also replace all the intake o-rings and when reinstalling the bank be sure everything is sealed up tight?
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WintrSol
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« Reply #10 on: February 18, 2017, 07:01:09 AM » |
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If you have a copy of the service manual, look at page 5-10. Once the vacuum line is removed, you can get to a screw that holds the valve in place. But, if your vacuum source holds a tight vacuum, you can just slide the hose off, and connect your vacuum source, and check to see that it holds.
The piston vacuum diaphragm, AFIK, is checked with a bright light that will reveal any holes.
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98 Honda Valkyrie GL1500CT Tourer
Photo of my FIL Jack, in honor of his WWII service
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Roidfingers
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« Reply #11 on: February 18, 2017, 11:30:26 AM » |
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So plug my mighty vac to either end of the hose ? And pump it up?
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WintrSol
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« Reply #12 on: February 18, 2017, 05:43:53 PM » |
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There is a short length of hose from a vacuum port to the air cutoff valve; I suppose you can connect the vacuum port to your pump to test it, or directly connect your pump to the valve. The manual says that, if you take the valve off the carb, you can see it working when vacuum is applied.
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98 Honda Valkyrie GL1500CT Tourer
Photo of my FIL Jack, in honor of his WWII service
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