Building and Flying Related Boards › miniMax, Hi-Max, and AirBike General Discussions
tomshepSeptember 28, 2018, 7:21pm
Friday afternoon and time off for bad behaviour. Have wanted to check the crank clearances and have invested in a Cyclone tester. 0.035mm front and 0.04 rear on a 200 hour crank. There are years left in the engine to my great relief. Version 7 of the fuel computer software looks promising as well and a bit of cleaning and touching up together with a coffee and a good chat with the lads up at the field rounded off a nice afternoon.
Tomorrow the weather looks fine and the day is my own. Looking forward to flying!
AntoniSeptember 28, 2018, 7:44pm
Tom, thanks for the info re prop.
The bearing tester may not be familiar to everyone outside the UK. It is a Dial Test Gauge held in an adaptor which screws into the spark plug hole. The engine is set with the piston nominally at top dead centre. A syringe on the end of a pipe attaches to the adaptor, and is used to create either positive pressure or a slight vacuum in the combustion chamber. The piston moves in response. The total of the conrod little end and big end 'float' is then read off the gauge.
Point is though, the reading is not a linear indicator of bearing wear or remaining life. The indication stays low for most of the life of the two bearings being tested, and then rises relatively sharply toward the end of useful life or the failure of the bearings.
I'd say it is necessary to use it very regularly if constant vigilance of bearing condition is wanted, or just a few times - say 5 engine hours apart - prior to any long water crossing for re-assurance.
Often seen adverts in the UK for aircraft or engines proudly stating very low float measurements. Meaningless.
Max SSDRSeptember 28, 2018, 8:40pm
I managed to pick up a Cylone tester off Ebay! Max came very well documented and that included a graph of crank wear (via the tester). As Antoni says, they stay the same while the crank is 'in life'. My graph showed an initial rise in wear as the new crank bedded in and then stayed fairly static. Can't remember what the readings were that I took but I'll take them again before I start her up. A useful tool nonetheless.