Carb Sync and shaved ears and decel cable - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 15 (permalink) Old 07-23-2013, 12:47 AM Thread Starter
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Carb Sync and shaved ears and decel cable

Just finished the Ear shave, looks freaking amazing. Bike starts up good, just got a new Glass Mat battery, now I want to sync the carbs. I build a manometer, not according to the versus but to this website instead:

http://www.obairlann.net/reaper/moto...manometer.html

Looks good, easy enough to build. I tried it once, and the Rear cylinder carb sucked all the water through like a straw. Obviously they are way off.

I didn't have enough time to adjust them yet, but they are set to 2.5 turns on each side. Anyone have some advice to keep that from happening this next time?

Also, it takes a few seconds to decelerate at an idle. Obviously it's because I didn't connect the decel cable, but I don't understand why it's even necessary. The throttle snaps closed as soon as I let it go. Can someone explain this to me?

Last thing, I promise. While doing the ear shave, I deleted some emissions crap, and left some hoses unplugged, and it doesn't seem to change a thing. Firstly, the Red and Blue ports on the gas tank are just unplugged now, is that ok, plugging them in while running seems to have no change. And on the T shaped splitter, I left one of the vacuum lines open. I attached a hose to it and fed it to be accessible outside the bike, so I could play with it. Plugging that with my thumb makes the bike idle higher and die on acceleration.

Whew, sorry for the long post. I can take pictures if necessary.

Thanks
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post #2 of 15 (permalink) Old 07-23-2013, 09:50 AM
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Quote:
Looks good, easy enough to build. I tried it once, and the Rear cylinder carb sucked all the water through like a straw. Obviously they are way off.

I didn't have enough time to adjust them yet, but they are set to 2.5 turns on each side. Anyone have some advice to keep that from happening this next time?
I did not view the Link, but use 15W or 20W oil....NOT water.

Quote:
Also, it takes a few seconds to decelerate at an idle. Obviously it's because I didn't connect the decel cable, but I don't understand why it's even necessary. The throttle snaps closed as soon as I let it go. Can someone explain this to me?
I have similar issues...believe it to be deteriorated "Enrichners" / Decelerator Valves ...Air Valves in need of replacement.


'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!

Last edited by WilliamTech; 07-23-2013 at 10:57 AM.
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post #3 of 15 (permalink) Old 07-23-2013, 09:58 AM
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If your throttle is closing but your idle is slow to return then it sounds like you have an air leak around your carb boots?

The 2.5 turns you are speaking about is the AF ratio screw, and it's not used for syncing.

I sent $30 on a sync tool off ebay that works without fluid etc.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #4 of 15 (permalink) Old 07-23-2013, 10:12 AM
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Originally Posted by AlienBacon View Post
Rear cylinder carb sucked all the water through like a straw.
Thanks
another indication of an air leak somewhere.. front cylinder most likely by that statement.

that device will respond exactly like you described if you have good vacuum on one side, and piss poor on other (either very low, air leak, or not connected to proper vacuum port)
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post #5 of 15 (permalink) Old 07-23-2013, 11:06 AM
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Timed out on me- lost my whole post.

Get it close with a single vacuum gauge first. Aggravating.
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post #6 of 15 (permalink) Old 07-25-2013, 04:42 AM Thread Starter
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Thanks everyone. Yea, the air/fuel mix screws are what I was talking about. I feel like a fool for mistaking it.

The boots WERE leaking. I readjusted them, and idle drops right down. I never did re connect the decel cable. Tell me, is it even necessary?

Haven't done the manometer test yet, will do when I find a 7mm wrench >_>

Back to Air/Fuel. I tried adjusting it by setting idle to 1000 rpm, then rotating screw out on a carb, until idle drops, then back in a bit. Thing is, when I turn the screw in either direction, on either carb. There is no change!
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post #7 of 15 (permalink) Old 07-25-2013, 05:40 AM
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Doing and having exactly the same thing

Ill write when i have time today. I am synching and my idle and throttle is all kinds of whacked

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post #8 of 15 (permalink) Old 07-25-2013, 07:07 AM
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Originally Posted by AlienBacon View Post
Thanks everyone. Yea, the air/fuel mix screws are what I was talking about. I feel like a fool for mistaking it.

The boots WERE leaking. I readjusted them, and idle drops right down. I never did re connect the decel cable. Tell me, is it even necessary?
It's a safety thing. You can run without it fine. But think about it like this...what if you are out on a back road in the middle of nowhere at dusk and the single throttle cable you have breaks? Uh oh. If you have both of them, you can swap that broken one with the other and keep on riding.

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Haven't done the manometer test yet, will do when I find a 7mm wrench >_>
I got mine in a set from Harbor Freight. I think they were like $5 for 6 metric wrenches.

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Originally Posted by AlienBacon View Post
Back to Air/Fuel. I tried adjusting it by setting idle to 1000 rpm, then rotating screw out on a carb, until idle drops, then back in a bit. Thing is, when I turn the screw in either direction, on either carb. There is no change!
Are you turning the air/fuel mix screw on the carb or the big black knob on the left side? The knob is the idle adjustment.

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Leave it to me to NOT be fond of something then end up banging it.
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post #9 of 15 (permalink) Old 07-25-2013, 08:14 AM
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Ok, at work so now I have time to type :-]

So my bike has an annoying buzz at 3500 RPM on up to at least 5k (haven't really been any faster because I'm afraid the thing will fall apart on me). It was suggested to do a carb synch. So I first started with the dual gauges. I just didn't get warm fuzzies from the dials. So I built my own manometer and I'll post some pics here soon. I used two stroke oil for my liquid.

When I first hooked it up, the rear carb was just about sucking the stuck up the hose immediately so I started loosening the bolt - counter clockwise. It's a bitch getting to the thing with any sort of normal tool. I go at it from the right side although others have said the left. So the result was that I did in fact get the two columns of liquid pretty close to even at idle but after the first ride the idle is at about 1500-2000rpm and will not go down unless I put pressure on the throttle to PUSH it down.

Part of the carb synch was to loosen your throttle so that the carbs are totally shut off by the throttle- for lack of a better way of saying it. I can only guess that I screwed something up. So my idle screw no longer does anything -it does not LOOK broken. I have looosened that up pretty much all the way trying to get the idle down. I think the problem is that now I have to adjust the throttle cables at the carbs. I have no idea how to do this.

I am also going to check the carb boots and I am assuming that it is the rubber that connects the carbs to the cylinder head.

As for the new bike owner Alien guy - I had lots of engine cutting off problems until I cleaned as many electrical connections and grounds using a dremel as I could get my hands on. Cleaning the switch UNDER the key fixed ALL of my shutting off problems - it's black and two screws gets it off after you remove the headlight bucket.

So anyway, that's where I am with this carb synch business. It's fun but the girlfriend is getting really annoyed that I spend so much time on the bike but the maybe I should get a new girlfriend

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post #10 of 15 (permalink) Old 07-25-2013, 08:25 AM
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Quote:
Originally Posted by Goofyfoot2001 View Post
So anyway, that's where I am with this carb synch business. It's fun but the girlfriend is getting really annoyed that I spend so much time on the bike but the maybe I should get a new girlfriend
She'll live with it..... then make up for it (spend a lot of time) during the winter (off season).
.

.

.

...or I forgot, that is season we perform a tear-down & repaint on our bikes !

LOL

LOL


'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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