2012 VFR800 "hopping"

[AndrewM]

G'day guys and gals,

 

I have a 2012 VFR800 and it is hopping at low speed (0-60kph) with revs 1-4k. It's not missing - where the revs would drop slightly, this is gaining maybe 200-300 revs. It's not constant but will do it maybe 2,3 or 4 times every minute or so, but not like clockwork, but enough to be a real problem. Very tricky around some roundabouts! I don't notice it at higher revs/speed - maybe because the difference is a smaller proportion of the actual revs??? I'm guessing really.

 

I thought it was water in the tank so I've run through probably three tanks now with 200ml of methylated spirits (which is basically ethanol) mixed in. The metho allows the water to mix with the petrol in smaller drop forms which are able to be burnt in the chamber. There are some good Youtubes on it. And I emptied the tank first (by lifting the front of it) to remove water as much as I could (didn't actually see any come out) and the inside looked clean. It seemed to help but the symptom (hopping) has now come back. Having diagnosed it a bit better now I would have thought water would cause it to miss (less revs), not gain revs so unlikely that was it.

 

Does anyone have any ideas?

 

Also, anyone know of a top shelf VFR mechanic in the Northern rivers of NSW or SE Queensland (Coffs Harbour to Brisbane)?

Thanks in advance.

[Grum]

First thought is maybe the Starter Valves need checking and Synching.

How long have you had the bike? How long have you noticed the issue?

 

Its interesting you mention an increase of 200-300rpm as this is about the RPM increase you get when you release the clutch when in gear to assist in take off. So, is it happening when clutch is released?

 

Are you seeing any Fi light codes flashing? How many K's has the bike done?

[eNiMaLx]

Dirty air filter? Dirty fuel injectors? Something wrong with the spark plugs?

Replacing the air filter is easy. For dirty fuel injectors I recommend running half a bottle of seafoam per full tank of gas. You'll have to get down and dirty to check your spark plugs. I recommend doing it on an empty gas of tank, and you don't need to remove the gas tank as you can remove the swinging bolts and swing it all the way to the rear of the bike while resting it on something soft and securing it with rope. Re-use torque is 1/8-1/4 turn after it seats and the replacement spec is if a 1 mm feeler gauge fits in there.