A few Extra Cranks and a High Idle a Minute Later

Happened for the second time yesterday.

2007 VFR with 3700 miles.

First time. I had her up on the center stand and washed the bike. I then lubricated the chain and also adjusted the tension of the chain as well. While on the center stand, I started the bike. It cranked for about 2 seconds or twice as long as a normal start for a better idea.

After 30 seconds, I backed out of the driveway and finally gave it some throttle as I went up the alley. It didn't take off as I expected. This could be normal as I am used to my carburated CB750 wanting to take of itself on cooler mornings with choke.

I turn right at the end of the alley and shift from 1st, to 2nd, and then clutch disengage, downshift as I come to a stop. Idle was MUCH higher now and seemed to stay the same as it was in gear before slowing down, probably 3 to 4K. Still had a loss of power when the clutch engaged at this RPM. I took it home. Let it sit for a bit as I went inside the house, come out to troubleshoot and it runs fine.

It has been about a month and it did the same thing this morning on a usual start up on the side stand. No wash, no center stand action. Just a morning like the mornings before.

As soon as I heard the longer start, I got a gut feeling it would behave the same way. I let it warm up for a tad bit longer too. Sure enough at the end of the street, Idle went up again. This time I gave it a little more throttle and everything was fine for the rest of the ride.

Thought it may be a vacuum leak but that doesn't explain the longer crank required to start. Fuel pump primed each time as well.

Has anyone else every experienced this? I assume I will again in about a month or so. I never experienced this on my 03.

 

Nobody? Some new findings. Since summer is long gone and mornings are much colder, I have experienced the high idle a few times. All of which occurred while starting to ride after no more than a minute to warm up. The extra cranks to start hasn't happened since my original post but the high idle has.

 

I would take a look at this guy:
[video=youtube;k4oVVbzTvVo]https://www.youtube.com/watch?v=k4oVVbzTvVo[/video]

 

Sensor starting to fail ?

 

The random high idle has been traced to a faulty fast idle wax unit. Replacing that seems to have fixed the problem in reported cases. Might want to consider replacing that, $40 + 1-2hours labor and it's pretty easy to do yourself.

 

Engraym

I had a very similar experience. Mainly in cooler weather. I started looking at the cooling system, and it was filthy with scale and slime. Lots of parts corroded. Replaced all hoses, water joints and thermo, including thermo housing. Was all happy, summer came and went, as soon as the weather started to dip into single figures (c), 4k idle again. Throttle body off again and replaced wax unit also....now all good!

I may have been able to clean up the old wax unit, as it was way clogged with the same scale and shit as the rest of the system was. The part is cheap enough, so I'm happy I just changed it. I've been through a full winter (in oz) now with no screaming idle.

I hope this is the cure for you mate, as I can relate to how frustrating/embarrassing it is. I would ride 50km to work, stop at the gate for ID check, with the bike screaming at 4k. I was getting some funny looks from the gate guards, I would just tell them that the bike hated the cold more than I did.

Best of luck with it, cheers
Ant.