Air Cut Valve Spring Question - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 10 (permalink) Old 07-15-2009, 02:08 PM Thread Starter
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Air Cut Valve Spring Question

I have two set's of carbs for a 95 VN 750, both have been opened up by previous owners and both came from different people. When I opened up the carbs to clean them out, I noticed on the air cut valve I have two different length springs. On both sets of carbs I have a long spring and a short spring in the air cut valves, on both sets the springs were on opposite sides. Looking at Ron Ayers, it shows both springs are the same part number hence should be the same length. I have the right springs since I have two short (about 3.4 inch) and two long (about 2 inch). Which ones are the right ones to use in the valves? Is there any reason why there would be 2 different size springs installed?
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post #2 of 10 (permalink) Old 07-15-2009, 02:41 PM
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The wider, longer, thinner springs (about 2 inches, thin metal, really flexible) should sit on top of the plastic housing (which sits on top of the needle) in the diaphragm of the piston. The short, thicker springs sit on the diaphragm of the coasting enrichener valve (you have to hold the cover on pretty strongly to get that first screw in - those are some serious springs!). There should not be two springs installed on the same part anywhere in the carbs.

C
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post #3 of 10 (permalink) Old 07-15-2009, 03:18 PM Thread Starter
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Correction: The short springs that I have that came out of the air cut valve are about 3/4 inch long, the long ones are about 2 inches long.

I thought I was clear but maybe not. I'm working on what Kawi calls the air cut valve. This is the valve on the side of the carb where the idle adjuster is bolted to on the Lt side. Maybe what you are calling the coasting enrichener valve though I don't know it by that name. The Kawi part number is 92081-1891. I have the springs in place for the needle valve and know they are right. I have two different size springs in the Air Cut Valve. From what I gather from your post it sounds like the correct spring would be the longer one.

Last edited by AceMcgyver; 07-15-2009 at 03:21 PM.
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post #4 of 10 (permalink) Old 07-15-2009, 05:23 PM
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In the manual it's called a coasting richener diaphram. As cindy said, the long springs go in the vacuum piston assembly and the short springs go to the coasting richener diaphram/air cut valve.


85 VN700 "Old Yella"

REBUILT ENGINE
CUSTOM PAINT
VANCE & HINES CRUZERS
EAR SHAVED AND RE-JETTED W/K&N'S
DUNLOP ELITE K591 FRONT & REAR
VOLTMETER
SYNTHETIC BRAKE FLUID
SYNTHETIC OIL & GEAR LUBE
PLEXISTAR 2 WINDSHIELD
SPLINES LUBED
ACCT'S GREASED W/TOC SPRINGS
COASTERD
LEATHER SADDLE BAGS
LEATHER TOOL AND ROLL BAG
PICKUP COILS GAPPED AT .018"
NGK CAP, WIRES, IRIDUMS
BARNETT FRICTION PLATES & SPRINGS
CUSTOM GRIPS, MIRRORS, LEVERS
ORIGINAL STATOR & R/R 14.5v
DEKA MF AGM ETX15L

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post #5 of 10 (permalink) Old 07-15-2009, 06:14 PM Thread Starter
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OK, I,m getting confused a little. This isn't a spring mix up issue with what I have. I have a mismatch in springs for the coasting richener diaphram within the same carb set. I know the springs that go on top of the needle valve and they are in position and correct. I have two sets of carbs for a total of 4 individual carbs. What I'm trying to convey is that on dissassembly, I found two different length springs in the coasting richener diaphram for each set of carb assemblies that I have.

When I took the carbs apart to clean them, one carb set had a long spring on the front carb coasting richener diaphram and a short spring on the rear carb coasting richener diaphram. On the other carb set the long and short springs were reversed.

Ron Ayers shows the same part number for both so I assume the springs should be the same length within the same carb set.

Between both sets of carbs I have two short - about 3/4" long, and two long - about 2" long springs that were previously in the coasting richener valves. I'm trying to figure out what spring length should be in there.

From what I gather from Crobins365 post, it looks like the longer of the two choices that I have is the correct one. The shorter one barely contacts the cap when I put it on and has very light pressure on the diaphram. The longer one takes some pressure to put the cap on. The reason I want to be sure that it's the larger spring, is that it seems to be a lot of pressure for the diaphram.
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post #6 of 10 (permalink) Old 07-15-2009, 08:01 PM
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As long as you have the correct springs in the piston Diaphram assembly then YES! use the longer springs for the enrichener/cut out.


85 VN700 "Old Yella"

REBUILT ENGINE
CUSTOM PAINT
VANCE & HINES CRUZERS
EAR SHAVED AND RE-JETTED W/K&N'S
DUNLOP ELITE K591 FRONT & REAR
VOLTMETER
SYNTHETIC BRAKE FLUID
SYNTHETIC OIL & GEAR LUBE
PLEXISTAR 2 WINDSHIELD
SPLINES LUBED
ACCT'S GREASED W/TOC SPRINGS
COASTERD
LEATHER SADDLE BAGS
LEATHER TOOL AND ROLL BAG
PICKUP COILS GAPPED AT .018"
NGK CAP, WIRES, IRIDUMS
BARNETT FRICTION PLATES & SPRINGS
CUSTOM GRIPS, MIRRORS, LEVERS
ORIGINAL STATOR & R/R 14.5v
DEKA MF AGM ETX15L

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post #7 of 10 (permalink) Old 07-15-2009, 09:00 PM
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https://www.vn750.com/photopost/showp...o=2603&cat=671

See if this helps sort out the confusion - this is the spring from the coasting enrichener diaphragm. The screws and cover are there for scale - do you have something that looks like this? It is heavy duty and seems like it's too strong for that little part - but it is the correct spring.

C
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post #8 of 10 (permalink) Old 07-16-2009, 12:40 AM Thread Starter
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That's it Cindy, thanks for the pic, that's what I'm calling the longer spring and is an exact match for what I have. OK so I'm going back with the longer springs, that sure does seem like a lot of pressure on that little diaphram though.

Now the question is where did the shorter springs come from? Is there anything else in the carb assemblies where a 3/4 inch length spring of that diamater is used? I assume they ended up there becasue somebody else has been into the carbs but I don't see anything missing from anywhere.
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post #9 of 10 (permalink) Old 07-16-2009, 08:03 AM
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Quote:
Originally Posted by AceMcgyver View Post
That's it Cindy, thanks for the pic, that's what I'm calling the longer spring and is an exact match for what I have. OK so I'm going back with the longer springs, that sure does seem like a lot of pressure on that little diaphram though.

Now the question is where did the shorter springs come from? Is there anything else in the carb assemblies where a 3/4 inch length spring of that diamater is used? I assume they ended up there becasue somebody else has been into the carbs but I don't see anything missing from anywhere.
At that diameter there really shouldn't be anything else in there. Each air/fuel screw has a very small-diameter spring in it; and there are the small, tight springs that go on both the idle adjust and the sync screw...but, again, those are small diameter ones. Oh, and another spring about the same size on the end of the idle adjust itself - but these are all really small. Hang onto 'em, but sounds like they're "extras."

C
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post #10 of 10 (permalink) Old 07-16-2009, 11:20 AM Thread Starter
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That's what I'm seeing also. All the springs that should be on the carbs are present and in the correct position, on the newer set of carbs the tamper plugs haven't even been removed for the idle screws yet. It's a mystery to me, I'll hang on to them though. Thanks for the help.
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