Fine Tuning the bike - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 15 (permalink) Old 10-18-2006, 10:13 PM Thread Starter
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Fine Tuning the bike

Ok,I put the carbs back in.Ouch! Anyway,I was so proud that I did it myself,as the Kaw dealer wanted $500.00 to do it.I found a ripped vac shutoff diaphram on the rear carb and also plugged jets.I cleaned everything and put it all back according to the book. I prayed,then started the bike.It started right up! It sounded meatier, but off sync.I took it for a short ride and know that it needs to be sync'd.I adjusted to pilot screws to about 2 1/4 turns out.I am now trying to get the sync screw somewhere in the vicinity of correctness.If it's way out of sync,will it be hard to make it idle right? Am I close to adjusting the pilot screws right? By the way,the Kaw dealership here in Hutchinson,Kansas,wants $90.00 just to sync the carbs! You guys and gals are the best,as you are owners and savy about our vn750's.Steve
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post #2 of 15 (permalink) Old 10-18-2006, 11:01 PM
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See crobins365's post on how she did hers. You will need to build or borrow a manometer. The cheap version is about $2 or so to build. That's how Cindy did hers. You can't sync the carbs by ear. The expensive route is to buy a manometer for min $50 or so. It's an easy procedure but you'll most likely end up shutting the bike down to adjust the sync screw as it's difficult to get to when the carbs are at idle.

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post #3 of 15 (permalink) Old 10-18-2006, 11:16 PM Thread Starter
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Will the bike idle rough when not in sync?
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post #4 of 15 (permalink) Old 10-30-2006, 04:55 PM
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I'd say so, especially if it's badly out of sync. If it's close, you'd need a manometer to tell. Clogged pilot circuitry in the carbs will also cause rough idle, but since you had the carbs off, I'm sure you cleaned them up good.

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post #5 of 15 (permalink) Old 10-30-2006, 06:15 PM
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Hey mendez, you didn't by any chance take pictures did ya? I've been thinking about re-jetting myself....
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post #6 of 15 (permalink) Old 10-30-2006, 11:09 PM
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Mendez 90 bucks is a bit steep.. but the norm.. Up here in Olathe.. any dealer wants over $100. I borrowed a manometer mercury style from a friend of a friend for my kz1000 OMG it was like someone flipped a switch.. When they are in synch it just runs soooooo much better of course that is a 4 cylinder. For a two it should matter also.

too bad I didnt have a set for ya to borrow.. I am heading out west this weekend for opening weekend hunting.
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post #7 of 15 (permalink) Old 10-31-2006, 02:22 AM
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you can make your own manometer with tubing a meter stick and oil..

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post #8 of 15 (permalink) Old 10-31-2006, 03:28 AM
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When you're through, you can dump the stick and use the rest as an enema. Make sure the oil is mineral or canola oil, though!

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post #9 of 15 (permalink) Old 10-31-2006, 08:30 AM
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Hey, Mendez!

Here's a link on the web for a $1.55 carb sync tool - (sorry - it doesn't appear to be a hot link). Works like a charm. The gist of it is that you're using 12 feet of pvc tubing against a yard stick (6 extra feet allows for the connections to the carbs), and then using a light oil (I used final drive oil in mine - fill so that the top of the oil is around 26" on each side) as your "barometer." Pull the vac hoses off the carbs, hook the manometer tubes (one to each carb) and turn the engine on. A higher draw in one tube means that carb has a higher vacuum - the carb adjusting screw (down by the throttle cables) adjusts *only* the rear carb (your goal is to adjust the rear carb so the vac is equal to the front carb).

If you need more info on how to actually do the syncing, just holler. A few of us have blundered our way through the process (some with a vacuum pump, others (like moi) without), and it *really* makes a difference in the bike's performance.


Last edited by Crobins365; 10-31-2006 at 08:33 AM.
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post #10 of 15 (permalink) Old 01-18-2007, 09:43 PM Thread Starter
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I made my own manometer and made it look really fancy.The problem that I encountered, was that one carb, I think the rear carb,tried to suck the oil out of the tube.I was lost then.
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