Rev counter suddenly reading very inaccurate

[28hodge]

Last rode at oulton, bike and rev counter was reading fine, started it a couple times since and 99% sure it was again reading fine, checked the valve clearances yesterday and swapped a shim, over, started up to warm through to do oil and filter change, and its reading about 7.5k on tickover, and I can blip it on the stands and it'll read at 16 its not tho its ticking over as normal at prob around 3.5k.

Anything I can check to see what's going on, got a spare cdi so could try that?

Any pointers?

[28hodge]

Changed the cdi no different! Cleaned the earth up on the front coil too still no change, annoying thin is I ain't touched it since finishing the last race at oulton at the start if June, doing the clearances oil and filter shouldn't have affected anything!!!!

[28hodge]

Tried a different battery, no change either, also looked at the earth at the back of the clocks, seemed fine took it out and gave it a clean up still no change! Anybody got a spare pair of clocks I can try I sold my spares as I was running outta room!!

[28hodge]

Spent all afternoon checking connections and changing things out and got no change, clocks are reading x2 all the time, think i have got a tacho coming to me which i can swap in but seems strage that mine has suddenly gone duff!!

All other gauges seem ok, i say all other, its a track bike so it only has the rev counter which is playing silly buggers and the temp gauge, but thats working ok!!

Anybody else had a tacho go duff? dont want to buy one an d then wait for it to arrive only to find out thats its not the problem!! i need it up and running for Donington with Bemsee on the 27th/28th

[KennonNC29]

I read somewhere on the fb vfr400 group that someone had the same issue was actually something to do with when the oil was changed some of the crud was messing up the sensor for revvs, think after riding abit more it cleared up

[28hodge]

Hmmm it started doing it before I changed the oil, I did the valve clearances and swapped a shim as I had a tight exhaust valve, then fired it up to warm the engine to drop the oil and that's when I noticed the gauge had gone duff.

It's a track only bike and I change the oil every 3rd day in track or 3rd race weekend so the oil doesn't get that crappy, but I'm kinda hoping it'll clear itself, but got a spare rev counter on the way.

Hoping that will solve it but if not I'm at a loss as nothing is standing out at the minute being wrong!!

[CMSMJ1]

Something must have changed mate... got to be a loose connection or someone has swapped an RVF tacho in..

[28hodge]

Yeah it's sods law it happens right when I am pushed for time to methodically work through it and suss it out, need it up and running ready for bemsee at donington. Hopefully changing the tacho will sort it, if not multimeter and continuity testing I guess!!!

Great, electrics, my favourite!!!

[28hodge]

So I got a spare tacho and went to fit it this morning. Before doing anything I thought I'd start it and see if the tacho was still playing up, so fired it up and ..............................











The tacho now reads correct again!!!

Not a clue!

[CMSMJ1]

Win

Love electrical faults.