Help please

[jpandflissy]

Hi guys,
New to the forum as I have just bought a 1993 VFR400 NC30 (import).
Have been riding an Aprilia RSV-R Mille and bought this for my wife as a first bike, but using it more and more for myself :D
Can you help.
I have 2 problems.
1st, when on the power it feels like it is missing from about 7k upwards with little/no power, would it be a jetting issue? ie running too lean?
Secondly and perhaps more strangly when riding on the motroway last week I was flat out and looked down to see the temp gauge off the scale? I backed off the power and the gauge went straight down (less than 1 second) then bakc on the power and back up through the red, off the power back down again.
Would it be an electrical issue, an air lock? any ideas and help would be great.
Thanks and happy riding

[CMSMJ1]

Howdo, and welcome!

The temp gauge - got to be an earthing fault I reckon. Check they are all clean and tight - I had the exact issue with a sweeping temp needle and the earth by the left hand front engine mount was loose. Nipped it up and it was all peachy.

this might cure your running issues too..

let us know!

MARK

[wullvfr]

yeah second that........other causes for the temp gauge to play up is if the cooling system has a air pocket in it but usually the gauge doesnt play up as bad as that........ :D

[Neosophist]

The earth for the temp-gauge is located near the front coils, you'll see it if you lift the tank off, make sure it is clean and securley fastened down.

If it was an air-lock it wouldn't go back down so quickly. However:-

To purge the system of air, run the bike on it's sidestand with the cap off, when the stat opens snap the throttle to 5000rpm a few times and switch the bike off, allow it to cool and top off with coolant as necessary, then replace the rad cap.

[jpandflissy]

Thanks guys, may well be an earth problem. Took the left crash boobin off (the one with the earth) and found it was just siting in there as the last bright spark managed to strip the thread on it, going to heli-coil it and try again.#
Then drain and bleed the system and see what happens.
Will let you know when it goes back together. Thanks once again