Professionally cleaned carbs...still runs bad! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 07-17-2007, 10:14 PM Thread Starter
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Question Professionally cleaned carbs...still runs bad!

So I sent my carbs (not on the bike) out to be cleaned, the float needle wasnt sealing and she would leak gas all over and flood out a cylinder (it took a month!) I got them back last week, put them back on and started her up. The problem no longer exists. I rebuilt the petcock, cleaned out the tank and tried to synch the carbs by sound (no manometer). I have her idling (by sound) better than she ever did in the 8 years we have been together. BUT, she runs like crap on the road unless I rev her waaaay up there. So at 85 MPH she feels smooth and sounds great, but from past idle till 6000 RPM she feels like a slug. She is de-goated, and has HD Dyna pipes....but she ran great with those mods for quite some time before the carbs got gummed up.
The question:
Does this just sound like a typical synch problem that could be fixed with the proper synch tools (manometer etc)
OR
did I get back a dirty carb? I havent had a real ride since May and I am going freakin NUTS!!!!!
I have an appt with the shop on thursday after work for an inspection and a synch... should I keep the appointment?

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away, and you have their shoes!

1994 VN750 Red/Black/Chrome
De-Goated (soon to have Dyna Pipes)
Chrome Diamond Grips
Chrome Coolant Cover
Chrome Tank Trim
Chrome levers
Chrome master cover
Stainless bolt set
Chrome shock nut covers
Chrome aftermarket mirrors (oval)
VROC #5817 (picture of bike at VROC pages)
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post #2 of 18 (permalink) Old 07-18-2007, 09:02 AM
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Someone once told me to sync the carbs by ear, but for the life of me I had no idea what I was listening to. So I built my own manometer and use that now for syncing purposes. Cheaper than a mercury one, cheaper labor (ha!), and if you leave the tubing from one side of the manometer on the exhaust pipe and it melts, it's a $1.00 replacement (not that I've done that or anything...).

Here's the link to the one I built: http://www.powerchutes.com/manometer.asp

Might as well try that yourself before heading back to the shop.

C
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post #3 of 18 (permalink) Old 07-23-2007, 11:20 AM Thread Starter
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well, It turns out I synched it by ear quite well. The mechanic told me I was not off by much at all. But she is still running crappy. he did temperature tests on each cylinder, synched them and rode it. It still runs like its not getting enough fuel at mid RPM's.
Since the carbs were professionally cleaned, I figure that it is not the carbs. But of course they could have done a poor job....see my dilemma?
Anyone know what else could cause the bike to run poorly at mid RPM's? and have no power?

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away, and you have their shoes!

1994 VN750 Red/Black/Chrome
De-Goated (soon to have Dyna Pipes)
Chrome Diamond Grips
Chrome Coolant Cover
Chrome Tank Trim
Chrome levers
Chrome master cover
Stainless bolt set
Chrome shock nut covers
Chrome aftermarket mirrors (oval)
VROC #5817 (picture of bike at VROC pages)
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post #4 of 18 (permalink) Old 07-23-2007, 12:03 PM
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Good job on the ear-sync! Yours must be better-trained than mine (I still can't quit my day job! )

When I was having trouble in the midrange with McKnight, turned out to be my rear coil. Maybe check your ignition coils - make sure the wires are attached properly to the coils themselves, and that the spark plug cap is firmly on each plug. But I found that out by looking for a vacuum leak - reportedly, if you spray WD40 around the carb boots, ducts, etc., if there's a leak, you'll experience an increase in idle. (I just saw sparks by the back of the airbox and realized that the coil was shorting...).

Here's a link to that thread and some of the suggestions. https://www.vn750.com/forum/showthread.php?t=4695

C

Last edited by Crobins365; 07-23-2007 at 12:06 PM. Reason: thread posted
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post #5 of 18 (permalink) Old 07-25-2007, 12:06 PM Thread Starter
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thank you for the response and the compliment!
Anyway, I think you may be on to something...I will definately check the coils and wiring. I just rode through a tank of gas/seafoam. I went 96 miles till the needle read empty. Now thats some crappy gas mileage!

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away, and you have their shoes!

1994 VN750 Red/Black/Chrome
De-Goated (soon to have Dyna Pipes)
Chrome Diamond Grips
Chrome Coolant Cover
Chrome Tank Trim
Chrome levers
Chrome master cover
Stainless bolt set
Chrome shock nut covers
Chrome aftermarket mirrors (oval)
VROC #5817 (picture of bike at VROC pages)
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post #6 of 18 (permalink) Old 07-25-2007, 12:33 PM
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Wow - that's pretty bad! I haven't checked my mileage since I fixed the coil, but I'm hoping it's better than that.

If you read through that thread, you'll pick up (hopefully) that if you're using a substance to check for a vacuum leak...but you are wondering about an electrical problem...use a non-flammable substance. Someone suggested Windex; I used WD40, which I believe could've left me without eyebrows...

In addition to checking for a coil short, jsut make sure that the wires to the coils (the red and the green) are actually attached. They're easy to knock loose, and also easy to forget about reattaching after having bits of the engine off.

C
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post #7 of 18 (permalink) Old 07-26-2007, 12:04 PM Thread Starter
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no vaccuum leak, and no visible short. All wires are attached and in great shape. I took apart the petcock too and it is working properly (with a new diaphragm).
Tonight I will look at the air filters, maybe they are gooped up, I did have them off when I took off the carbs but I did not look them over.....
if no luck then I will assume the carbs are still junked up and bring it back to the shop. This problem began AFTER I had the carbs cleaned. The carbs used to spill gas which was definately fixed, but now it runs poorly...

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away, and you have their shoes!

1994 VN750 Red/Black/Chrome
De-Goated (soon to have Dyna Pipes)
Chrome Diamond Grips
Chrome Coolant Cover
Chrome Tank Trim
Chrome levers
Chrome master cover
Stainless bolt set
Chrome shock nut covers
Chrome aftermarket mirrors (oval)
VROC #5817 (picture of bike at VROC pages)
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post #8 of 18 (permalink) Old 07-26-2007, 12:22 PM
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Quote:
Originally Posted by weasel750 View Post
no vaccuum leak, and no visible short. All wires are attached and in great shape. I took apart the petcock too and it is working properly (with a new diaphragm).
Tonight I will look at the air filters, maybe they are gooped up, I did have them off when I took off the carbs but I did not look them over.....
if no luck then I will assume the carbs are still junked up and bring it back to the shop. This problem began AFTER I had the carbs cleaned. The carbs used to spill gas which was definately fixed, but now it runs poorly...
Hmmm... definitely check the air filters (folks have found that they've crumbled in situ) and the ducts to the airbox; but unless the shop is willing to take care of your carbs gratis, I'd suggest thinking about cleaning 'em yourself (my motto: If I can mess up for free what I can pay a professional to screw up, I think I'll do it myself...).

Can you give a more detailed description of what "running like crap at mid-range" looks and feels like? Like, can you even take the bike to WOT and have it run?

C
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post #9 of 18 (permalink) Old 07-31-2007, 09:44 AM Thread Starter
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running like crap:
It idles like a dream, and even revs nice in the driveway, but put her under a load and I have no power. I can get her up to cruising speed, but it does not have any pull, it kinda "breaks up" and I can tell that it is not running at peak performance. In fact going up a steep hill (that I usually can keep pulling to the top) I cannot even go 55mph! I would not even dream of passing someone on the flats...I worry I wont get around them.
She is in the shop right now waiting for new air filters so they can put her on a dyno.
I just want to ride!!!! this is starting to make me angry.
my wife was riding in a car on the way to drop off the bike, she said my exhaust smelled funny...not like gas from the can but not right.

Before you criticize someone, walk a mile in their shoes. That way when you criticize them, you are a mile away, and you have their shoes!

1994 VN750 Red/Black/Chrome
De-Goated (soon to have Dyna Pipes)
Chrome Diamond Grips
Chrome Coolant Cover
Chrome Tank Trim
Chrome levers
Chrome master cover
Stainless bolt set
Chrome shock nut covers
Chrome aftermarket mirrors (oval)
VROC #5817 (picture of bike at VROC pages)
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post #10 of 18 (permalink) Old 07-31-2007, 10:11 AM
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I was having trouble with McKnight awhile back, and it turned out to be the rear igntiion coil. Changed that out and it was fine. But then I sync'd the carbs and put the engine guard back on last weekend, and it ran like crap - like the kinda crap you're describing - all over again. Changed the plugs, swapped out the coil, still ran like crap (I couldn't even hit 45 mph!). So I pulled the air filter housing units and one of the ducts going to the airbox had come loose at the bottom, in an area where you really can't see it unless you pull the entire housing unit. I'm figuring that duct is perhaps a little "tired" and I probably smacked it a time or two trying to get the engine guard back on. Took it out yesterday, ran great again (65 mph, WOT, no break-up at all).

The thing about vacuum leaks - even small ones - is that it's like trying to drink a Coke with a hole in your straw. Just not enough suction to get fuel into the carbs. Works ok at idle, 'cause there's no airflow, but once you're moving, it gets all messed up. I'm still thinking they did something when they "professionally" cleaned your carbs - either didn't put a gasket in right, or there's a small leak in there somewhere. That's gotta be really frustrating -not just not being able to ride, but having to keep taking the bike in for service.

C
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