The bouncing needle of the tachometer

Podczas jazdy i na postoju, przy około 2000 obr./min igła przeskakuje, silnik ma normalną moc, a wszystkie świece zapłonowe są brązowe. Co może być przyczyną?


While driving or idling, at approximately 2000 rpm, the needle skips, the engine has normal power, and all the spark plugs are brown. What could be the cause?

You may find using "google translate" or similar so you can post in English will help you reach a much wider audience 
The tacho pulse comes from a "node" crimped connection in the loom for the ignition system. Over time these connections corrode. You could check that



 

Thanks for the tip, I checked the connections and nothing has changed, on Facebook they suggested cleaning the carburetors. I am waiting for new repair kits.

GrzegorzSadoch wrote:

Thanks for the tip, I checked the connections and nothing has changed, on Facebook they suggested cleaning the carburetors. I am waiting for new repair kits.

Is the engine speed fluctuating or is just the tacho "flicking" ? where are your repair kits coming from  (many aftermarket kits aren't great !!!)

I ordered the sets from AliExpress, the rotations do not change.

GrzegorzSadoch wrote:

I ordered the sets from AliExpress, the rotations do not change.

If the engine speed is constant but the tacho is flickering then it's not carb related (it's electrical) and I would try and keep away from cheap carb kit's  !! you will likely create problems you don't have currently 

I received parts for the carburetors, but after disassembling, the filters in cylinders 1 and 4 looked like this. I replaced the jets and filters with new ones, and the problem stopped. I need to do a test run, but the weather doesn't allow it.

I am surprised that the engine ran at all. I hope that you completely disassembled all four carburetors and carefully cleaned every tiny passageway. I would also take apart and clean the entire fuel system. If any of that goo is in the fuel tank, fuel valve or fuel hose, it will get back into your newly cleaned carburetors.

Also, I hope the parts you got from Aliexpress are useable. Proper high quality parts are essential for these old carburetors to work as they were designed. Keyster and Jets R Us seem to be the most reliable sources these days.

I did a test drive of about 50km, smooth ride without jerking, the needle is not jumping, I think it will be fine - thanks and best regards.