Kawasaki Vulcan Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
408 Posts
Discussion Starter #1
After searching through old threads to no avail, I wanted to see if the off idle hesitation when cold can be cured by some method other than installing a fuel processor? Has anyone been able to successfully remedy this problem without shelling out the cash for something that I really don't need?
 

·
Registered
Joined
·
11,747 Posts
Some questions:

1. What year is the bike?
2. How many miles?
3. How long have you owned?
4. Did the problem just start overnight?
5. Any aftermarket mods...pipes, etc?
6. When you say "cold", how cold?
7. Is it just a slight stumble or a big sag?
8. Any other driveability issues?
9. Any other problems, no matter how unrelated?
10. Any recent work?
 

·
Registered
Joined
·
408 Posts
Discussion Starter #3
2008 VN2000LT, owned since new 2/2010,6200 miles currently, problem has existed since new, can't tell if it's bugging me more than it used to or it's getting worse. Zero mods except for the luggage rack. Cold as in the engine is getting up to temperature, within the first 5 or so minutes after cold starting regardless of ambient temperature. Seems like a big sag, as if turning the ignition off for just shy of 1sec. Only happens with partial (0% - 15%) throttle application. No other drivability issue, just random rattles, most of which I know where they're coming from and why. No recent work, but have been riding less this year than previous years, doesn't change if the gas in the tank is a month old or a day old.
 

·
Registered
Joined
·
11,747 Posts
1. If you feed the throttle gently, does it do it?
2. If you take off faster does it do it?
3. Does it do it in all gears?
 

·
Registered
Joined
·
574 Posts
If you are talking about when you blip the throttle while not under load, my 2011 Nomad has done this since new. I've gotten "some" of it out by playing around with my PCV, but still haven't perfected it.

I'm also going to do the Thunder Gasket soon, since I may have an intake leak contributing to this.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #6
It seems to not do it when feeding the throttle slowly, but when maneuvering out of the driveway, the slight throttle applications need to be pretty quick at times. Seems to do it if I take off faster, as I still have to go through this throttle plate angle/load situation, unless I were to just hold the engine speed over 2000rpm or so until it was warm enough for the symptom to disappear. Don't know if it does it in all gears, in neutral for sure, and in first, but after that, the engine is usually spinning fast enough to keep the problem at bay. It seems directly proportional to slight but quick throttle application from high idle while still warming. I can't say definitively when it stops but it's not too long after getting moving and I've always let it warm up for at least 3 minutes before taking off.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #8
That's exactly what it feels like, just not sure why the symptom would go away after the engine builds a little temperature. If I let the bike sit and idle for like 10 minutes after a cold start, it doesn't do it, usually just within the first 5 or so minutes.
 

·
Registered
Joined
·
11,747 Posts
Could be that when the actuator is cold, there is a bind somewhere that goes away once the engine heat gets to it.
 

·
Registered
Joined
·
2,967 Posts
My 2008 VN2K does the same thing if I try to blip/crank the throttle before it is good and warm.

The idle speed hasn't been turned down?
 

·
Registered
Joined
·
408 Posts
Discussion Starter #11
The idle speed after complete warm up is between 860rpm - 880rpm which is within spec, but it does this most noticeably when the engine is still running at high idle. I haven't confirmed the high idle speed, but it sounds good and much the same as every other VN2000 I've run across. It's most frustrating because I have to drive the bike as if it will die at any second, which it hasn't yet, but I have gotten it to stall while trying to replicate the problem for further diagnosis.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #12
I'll remove the air filter to see if I can identify any delay or binding with the sub-throttle linkage or actuator.
 

·
Registered
Joined
·
2,967 Posts
I suspect it's something in the fuel mapping (probably on a leaner point than the bike is ready for at that point, would be my guess), but if you find something with the sub throttle I'd sure be interested to hear about it.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #14
I suspect a fueling issue as more than one person has mentioned curing the "stumble" with the addition of a power commander. I really don't want to go that route as I don't need any more power, and certainly don't want to be burning any more fuel than I am already.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #16
Well I finally got a little time to do some more research on my problem. After turning the ignition on, the sub-throttle (pre-throttle) goes through it's homing sequence and remains completely open. Starting the engine cold leaves the pre-throttle wide open on high idle where the symptom is most prevalent, and does so with very slight throttle angles, less than 5 degrees. After warming up, the pre-throttle closes almost completely, the symptom becomes much less noticeable to the point where the engine cannot be killed by manipulating the throttle, and the pre-throttle begins to open as needed based on primary throttle application and engine speed (and probably load too). Given what I have discovered, this is clearly a function of the way the fuel management was programmed when the engine is cold.
 

·
Registered
Joined
·
408 Posts
Discussion Starter #17
Forgot to mention, I saw no pre-throttle linkage, given the limited disassembly I performed. It appears to be a direct drive stepper motor, much like the full drive by wire throttles on most new cars and more and more new motorcycles.
 
1 - 17 of 17 Posts
Top