I have a 2014 model Honda BF50D with 540 hrs on the clock.. I have used it often last year and this summer, all fine with no probs.. the boat is at home now for the winter but I start the engine once a month and let it warm up then run at 2000 rpm for 10 mins or so... it is in a big tub of water whilst doing this, I leave it in neutral coz the prop is fitted.
The problem..................
The engine starts perfectly first time, i let it tick over to warm up for 5 mins then set it to around 2000 RPM.... when I did this the other day The motor would run at 2000 RPM for 40 seconds then rev up to 3100 for 5 to 6 seconds and then drop back to 2000 RPM again, and repeat this for 10 mins before I turned it off....
What could be the cause of this fluctuation of RPM all on its own !!!
I dont have a clue where to start looking..
Any sensible suggestions gratefully accepted..
