hugomez wrote:Hi Lars and Lasse,
Just back from the test of the wire from ignition to coil. Result: right cylinder didn't start.
As Lars say, with this I think I have test all electric options, because swapping parts and replacing others there is no one component assigned to the right cylinder that I have not been tested. Nevertheless I will have another closer look to all wires to see if I am missing something that I still didn't test from there.
Lars, because was confirmed that the problem was not the carburetors, I have put again the twin 18mm on it. The 22mm drop some fuel after the test (maybe because the float bowl not been 100% straight), so I feel more comfortable doing the next test with the actual components I will have in the future on the bike.
The fuel tap (petcock) is fixed. At least this is what I think after adding two new fibre washers. Tomorrow morning I will know for sure. The problem with the "hard to turn" handle is now clear. The solution is to unscrew a bit two small screws that compress a piece of metal that is a bit curve. As more tight it is, the curve metal start to get flat and making pressure, and as more pressure, the harder is to turn the handle. I set in a way that was soft to turn, the handle, however fuel was coming out from there, so I tight it again. At the moment I do not mind anymore if the handle is hard, as long as there is no leak.
What to do next?, Going to the bar with some friends now. Tomorrow we will see.
OK, makes sense to use the correct carburetors. But now you know the problem is definitely not there, so you can turn your attention to other areas.
I agree with Arthur that the some sort of crankshaft seal problems is the most likely source of the problem. A problem with pistons or cylinders, for example, is very unlikely to improve when the cylinder finally starts to fire. But a crankshaft seal could leak in one direction (under vacuum for example) and start to seal better once the cylinder starts firing. It is conceivable at least.
If you want to test the crankcase for that type of leak under both pressure and vacuum conditions, I could lend you my test kit with the Mityvac pump which I wrote about in another thread. In that test you put the piston in the bottom position (transfer ports open), and block off the intake and exhaust ports on that cylinder. Then you connect the pump to the spark plug hole, pump up pressure and see if it holds. Then you switch to vacuum and pump up vacuum and see if that also holds over a period of time. I have the adapters and plugs needed to use the Mityvac kit on a Rumi engine.
I would be happy to send it to you if you think it would be useful to do such a test.