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Carburator Problem

3K views 12 replies 7 participants last post by  Tom G 
#1 ·
First, I am trying to locate Sfair who was recommended to me by my friend, Red Fish.

Of course, I will humbly accept help from anyone who wishes to contribute.

I have a 2009 Vulcan 500 that I just bought used with only 1,215 miles on it. I immediately had my mechanic check everything on it from brakes to engine to tires (I had him install new Michelin Commanders).

When the job was completed, my mechanic told me that when I backed off the throttle I could expect a short carburetor lag, but that it was nothing unusual.

Upon riding it for a Sunday outing of over 340 miles, I was rather surprised that the carburetor lag was more than just noticeable. In fact, down-shifting to slow the bike resulted in a "Torky" surge.

Yesterday, for 3 hours, my mechanic religiously checked everything including the diaphragms, needle valves, cables, throttle play, gaskets, and much more than I know about. Everything checked out, but the carburetor lag was still there.

The consensus between him and his mechanic partner is that something is happening with the vacuum (hoses probably) that is causing the problem. They are going to consult with the Kawasaki mechanics here in Jacksonville to confirm their suspicions.

Any thoughts on this matter?

I will be gone today till evening but will respond to all messages.

Thank you,

Tom G
 
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#2 ·
Wish I could help, but just want to say stick it out. I will follow this thread with great interest.
The only thing I can offer is the observation that my throttle handgrip would not spring back to the idle position when I eased off the gas. Turns out after much trial and error that I took it to my mechanic and he found that the "crampbuster" accessory that allows my palm pressure to help hold the throttle open was straddling the stationary rear end of the handgrip and thus not allowing it to return...Duuuuh on me I know, but I am pushing 80, so at least I have an excuse.
 
#3 ·
You need to narrow down the problem.
Is the throttle physically sticking? It should snap back shut firmly when you release the grip. If not, focus on the grip, throttle cables, etc.
Is there a vacuum leak? You can check for this with a visual inspection first. There are only two vacuum lines on the bike: one from the left side carb to the fuel valve, the other to the emissions system. For diagnostic purposes, you could cap each of those off and switch the fuel selector to Prime. If that hasn't solved the issue, try an unlit propane torch. Open the gas valve and slowly move it around the engine. A vacuum leak will suck the gas in and cause an increase in RPM.


Honest (and unsolicited) opinion? I'd question the ability of your mechanics based on their suggestions and their need to contact a Kawasaki mechanic. Whatever this is, it's a generic engine issue, not something specific to a Kawasaki motorcycle.
 
#5 ·
I am assuming by what you mean by "carb lag" is that the engine takes a while to slow to idle speed.
Follow fastpakr" advice except for the propane bit. Not very safe if you should have a high tension spark leak somewhere.
Instead, fill a squirt bottle with soapy water and spray around carb boots and carb. If you see bubbles getting pulled in, you have found a vacuum leak.
 
#6 ·
Thanks Fastpakr,

Checking for a vacuum leak is the next step; my two mechanics also suggested that next, and agree with you on that. And, true it is a generic engine issue, but asking others who might have experienced this problem is not a negative thing. They just happen to know the mechanic at the near-by Kawasaki dealer.

I will keep you & the forum updated.

Tom G
 
#7 ·
Hey Bokobob,

Thanks for replying, and I see you use the "Age Card" now and then.

Well, I'm 78 and 80 just around the corner for me too..

My new motto is: "Pushing 80 Is Exercise Enough".

Feel free to use it when appropriate.

Tom G
 
#9 ·
an '09 with just 1200 miles

i'll likely be blown off....but I'd suggest a valve clearance check which "the book" calls for at 600 miles...aka the first service. Highly doubtful a check was actually done.

the EX have a habit of being found with tight valves at alarmingly low mileages (my experience more with the EX variant)

Did the mechanics consider them? or blow a valve check off?

Frankly, I'd start on the inside and work outwards.

PS.... are the carbs equipped with a "jet kit" or stock jetting?
 
#11 ·
Carburetor Problem Solved

After my guys spent another few hours cleaning the carbs, checking the hoses for leaks, float valves, “O” rings etc., and searching for any possible glitch, and came up with NOTHING; one of ‘em decided to adjust the Air/Gas valves to a setting differently than the books says.

Not sure what the book says, but I think it said 1 to 2 turns. Finally, they turned the fuel (maybe both) 4 turns out, and the bike started and ran like a Swiss wristwatch.


I am not a mechanic, but these two fellows are people I trust. And, when they refused to give up and started experimenting; then
when the bike started to run perfectly I figured the manual might have been wrong.

Oh yes, both carbs had new jet kits installed.

Anyway, the bike runs wonderfully, and i appreciate all the interest, help, & suggestions.

Tom G

P.S. I don't think the valves were inspected, but it seems odd that they would need to be checked at only 600 miles.
 
#12 ·
If your talking about the Idle mixture screws 2 1/2 turns is only a starting point.They should be adjusted with the bike idling warm to the smoothest fastest idle.Do adjustments slowly so carbs have time to adjust to changes. :)
 
#13 ·
Carburetor Problem Solved



Thank you Blaine. I have no doubt that you are Right as that's what happened. As I recall my two mechanics (co-shop owners) did not interpret the Service manual saying that 2 1/2 was the "Starting Point". In the end, I think the screws were turned out about 4 turns or so, which seemed excess, but the bike runs like a Champ.

I didn't ask what exactly the Manual states & my manual was just ordered & is in the mail.

Again, Thanks.

Tom G
 
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