Kawasaki Vulcan Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter #1
My bike has developed a dead spot or almost like it cuts out for a split second under aggressive acceleration just off the closed throttle position. Makes no difference what gear I'm in, or what speed. If I let off the throttle, then hit it rapidly from a closed throttle position it has this symptom.

If I ride "non-aggressively" and just slowly/ smoothly roll onto the throttle I don't notice, however if I "nail it" I get this annoying symptom.

Anyone else experienced this, or have ideas what is causing it?
 

·
Registered
Joined
·
364 Posts
Are there deposits in the throttle body preventing the butterflies from moving freely?
If so, a good cleaning might fix the problem.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #4
I took the right side dog bowl off and the throttle plates looked clean and move free.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #5
What RPM.... 1700 or 2200 Are the temps up past center? Fan on?

Not sure what you are asking...
The fan does not come on when I'm going down the road, my temp (on a warm day) is usually near center.
 

·
Registered
Joined
·
547 Posts
The ecu goes into safe mod at some point and I had a stumble when this would occur. Might be gas related as well. You running 89, 91 or 92. Mine did it for a bit then it disappered. Mostly at 1700 rpm.
 

·
Registered
Joined
·
3,887 Posts
Mine had a stumble to it at low rpms, under 2200 or so when I had a speedometer correcter on it. After removing it, I have not had the stumble since. This is on a 2012 Voyager. I have a Gman fuel controller and drilled baffles from my stock pipes. I did have a Thunder stock air kit on for a couple years but removed it last spring and went back to stock intake.
 

·
Registered
Joined
·
701 Posts
The stumble can be fixed by getting the ecu flashed by Ivan. Look him up here you will se what I'm talking about. It's the best money you can spend on your bike!!
 

·
Registered
Joined
·
33 Posts
Discussion Starter #9
I like what I've read about Ivan's ecu flash except I have a hard time always finding 91 octane fuel. Most of the fuel around here is 87 only. I know that Kawi recommends always using 91 and I do every time I can, but not always an option on the road. My bike did not have this stumble for the first 20K miles or more, but at some point it began to do it enough that I now notice it. Currently have about 34K miles.
 

·
Registered
Joined
·
1,192 Posts
stumbles like this are caused by closed throttle position then you open throttle and it stumbles, it's not by rpm's but rather by throttle position. I think what's happening is the motor stumbles from less fuel after throttle is completely closed then opened again, the fix might be to get the ecu to add more fuel in one of the pots, I don't know which pot is which on fuel injections but the motor does not care if its carb or fuel injected, a lean condition just off throttle is a lean condition so you're going to need a powercommander or whatever they are called and flash the pot to increase fuel for that throttle pot# position
 

·
Registered
Joined
·
1,192 Posts
and speaking of 91 octane, find out what compression ration your motor has, if it's under 10:1 then do not use 91 octane, use 87 regular, 10:1 compression ratio is the dividing line between regular gas and upping it to next level.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #12
and speaking of 91 octane, find out what compression ration your motor has, if it's under 10:1 then do not use 91 octane, use 87 regular, 10:1 compression ratio is the dividing line between regular gas and upping it to next level.
I miss spoke, Kawi recommends 90 not 91 octane in the owners manual. After a quick search on the web, the 1700 engine is 9.5:1.
Although 87 octane has always agreed with my bike (never noticed any pinging) but if I decide to have Ivan's ECU flash done to correct the air fuel and timing... I've heard others state that they have had detonation occur under heavy load if not using at least the recommended octane fuel.

I think you are right about this issue most likely being caused by a lean air fuel mix at that throttle position where it is happening (just after rapidly opening form full closed) since it is fairly well documented that Kawasaki designed it to be very lean for EPA requirements. I may have made the condition worse by changing the factory exhaust to a Vance and Hines 2 into 1 system?
 

·
Registered
Joined
·
1,192 Posts
the 1700 engine is 9.5:1

that takes regular 87 octane because it's under 10:1
 

·
Registered
Joined
·
388 Posts
the 1700 engine is 9.5:1

that takes regular 87 octane because it's under 10:1
Compression ratio is not the only determining factor in what is needed for octane. I have seen 11:1 engines that run perfectly fine on 87, and I have seen 9:1 engines that needed 91.
 

·
Registered
Joined
·
669 Posts
1700 engines require premium fuel, the octane is not so important. I've discovered our ratings here are different to yours, so after the flash 91NZ octane pings, but 95NZ octane is problem free. Pre flash, I ran 91 just fine with a fuel controller, pre fuel controller, I had to use 95. Ivan told me to do my research... only 95 is premium, 91 is regular.
 

·
Registered
Joined
·
388 Posts
1700 engines require premium fuel, the octane is not so important. I've discovered our ratings here are different to yours, so after the flash 91NZ octane pings, but 95NZ octane is problem free. Pre flash, I ran 91 just fine with a fuel controller, pre fuel controller, I had to use 95. Ivan told me to do my research... only 95 is premium, 91 is regular.
Octane ratings differ between New Zealand and the U.S., which is why 91 is regular over there while it is premium here. I would guess that the octane rating over there goes by the higher number while over here, it is the average of the two numbers.
 
1 - 16 of 16 Posts
Top