Sudden momentary RPM surge when cold

This has happened a few times recently.

Bike: 2006 VFR800A
Mileage: 169,000 km ( about 105K miles)
Well maintained
New Stator Approx 10K km ago (May 2012)
rectifier X2 85615 km (July 2009)

On a cold start, I immediately get on and away I go. Come to a stop nearby and as I gently roll on the throttle, the RPM. suddenly jump, to what seems like about 8K rpm or even higher very momentarily then returns to normal. First couple times I thought it was just me getting used again to the heavier gloves, but it happened again this morning and I was wearing summer gloves.

I don't let the bike warm up. Just start, jump on and go. This happens within a minute or so, the first time I stop then resume on the throttle. This problem then disappears. It runs very well otherwise at all speeds and rpms.

No codes light up at start up either.

Scares the shit out of me.

Anyone with any ideas before I take it in to someone and lay down copious quantities of money?

 

The wax unit....maybe do you have PCIII might want to reload the map.

 

What is a wax unit? No PCIII.

 

Check this out

http://vfrworld.com/forums/mechanic...dle-wax-unit-starter-valve-synchronizing.html

 

Stuke replied to this but for some reason it did not show up on here.

So in answer to his questions
1. no
2. yes
3. possibly, I will check that out
4. I don't think so but I will check
5. You mean fuel injector cleaner?

 

Yeah, I'd go with #3. IMHO

Seriously though, the wax unit usually only drives the revs up to 4k and is not momentary.

My first guess would be the TPS is on its way out, but it's strange that it only happens when cold. That means it's going to be hard to duplicate, for troubleshooting.

 

Thanks for that. So. I dug into the TPS a bit. What I have found out on the incredibly accurate internet, is that there should be an error code by the FI light flashing 8 times. No such thing has surfaced yet on my bike. Maybe that is to come yet. Going out for an early morning ride today and it is cold here so I will watch more closely for exactly what happens.

 

It is beginning to look like the bike goes into the shop for this fix. Seems a little over my head technically speaking. But that will be later. Wheels go to Kelowna next weekend for powder-coating first. On my way down to the US right now to pick up some angles valve stems for the wheels in a few minutes.

 

The code only gets set for a certain specified error. This is often an open, or a short circuit. In your case, it would probably just look like you were a squid needlessly revving your engine to 8k.

Unless the snag can be duplicated by the tech, you might as well spend your money on more beer, so you can at least get some enjoyment out pissing your money away.

In the mean time, it wouldn't hurt to check the tps and map sensor connectors for cleanliness and maybe do the tests from the service manual.

 

That is exactly what it looks and sounds like. Right on. I went out this morning to pick up something in the US and tried to see if it would do it again. Temps here this morning were 6c and I started and rode it right away. Wouldn't you know it, no problems noted. That sux.

Your point about the beer is very well taken and appreciated. So long as it is not Budweiser or Blue. Canadian is not much better.

 

OK who nicked the "like" button :spy:?

Even so I'll drink to that idea - its freezing cold, its snowing:smow: and the bike is abandoned in the garage - so I guess it time to christen The Mcallan.

Cheers




SkiMad

 

Which would you like me to have. The Mcallan 12 or the Mcallan Estate Reserve.

 

Have some Scotch chill and keep on riding Randy