Tachometer reading about 5x too high

Sorry my poor English

Just got 2009 WR250R with 290 Big bore kit. I can't ride it yet, because of snowy roads. It has many mods (cat, exup, etc deleted) and speedohealer 4.0. I have fixed few problems, mainly electrical because of poorly made connections. I just soldered everything and bike seems working now, without error codes.

Weirdest problem left is that built-in tachometer reads about 5500rpm on idle and 9999rpm when giving slight amount of revs. I haven't found anyone with this problem, so Im pretty much clueless.




Background:
Previous owner bought it about a year ago. Before that, it was sitting in a garage many years. He wanted to be sure everything is ok, so he replaced piston, timing chain, tensioner etc. He also said, he checked the valves. I have that original 250cc block and piston (pristine) and that replaced 290cc piston, which is also in very good condition.

It has just 5600km.

Also, I don't know much about that speedohealer... I just reset it and the test procedure works.

Forgot to add this:

It has aftermarket front cowl+headlamp unit and heated grips, and blinkers.
Heated grips have low and hi settings, only low setting works. Electricity for the heated grips is taken from the parking light (5W) and maybe somewhere else, idk? All those connections look like sh*t, too many connections and too much wire. If I want to sort that mess, I have to remove everything and start over. Don't know, if some of those wires are connected to the instrument panel and if that messes up the tachometer? I don't know much about electronics.

WR290R wrote:

Weirdest problem left is that built-in tachometer reads about 5500rpm on idle and 9999rpm when giving slight amount of revs. I haven't found anyone with this problem, so Im pretty much clueless.

Another member had the same problem recently in this thread, and his bike had numerous other problems as well. He managed to fix almost all mechanical and electrical issues, but he was never able to resolve the tachometer reading high.

Given that your bike seems to have some electrical installation issues, I would suggest removing all these add-ons and see whether the situation improves.

Thanks for your reply and link to that other thread.
My bike is not that bad. Everything is working now. It idles fine. Spark plug have right color. No leaks anymore (exhaust gasket and fuel line had some leaks previously).

I found out there is a flaw in this model which makes speedometer read 3 times too high. I think I have this problem, but easily fixed with Speedohealer. Maybe this issue also affects tachometer? Have anyone noticed, who have this 3x too high speedo issue to check if tacho is also wrong?

WR290R wrote:

I found out there is a flaw in this model which makes speedometer read 3 times too high. I think I have this problem, but easily fixed with Speedohealer. Maybe this issue also affects tachometer?

The previous poster that had the tach 5x problem did not have the speedo 3x problem, so these two issues seem to be unrelated.

You can check whether you have the speedo 3x problem without actually riding the bike: put it on a stand to elevate the rear wheel, start the engine, put it in first gear, and let it run; the speedometer pick up is at the countershaft, so the speedo will show some speed.