Rob, Thank you. After spotting a tiny hole in the diaphragm I temporarily sealed it pending the delivery of the new one and the issue of rough running above certain RPM value seems to have gone away. I really hope that things work the way you described because that would probably mean the put our finger on the root of the problem. I also intend to conduct an experiment once the new diaphragm is here. I want to deliberately puncture the old diaphragm and see if the the problem comes back again.
Best regards Jarek On Sun, 17 Nov 2019 at 09:12, Rob Thompson <[email protected]> wrote: > Hi Jarek, > The vacuum from the engine holds the piston up when you apply power. > If there is a hole, the piston will sit lower or if the hole is big enough > won't lift at all! > Either way you will get a restricted fuel/air flow to those two cylinders > and they will be out of balance with the other side. > A small hole = rough running. A big hole = very rough running. > > regards > Rob > > Rob Thompson > 0429 493 828 > > > > On Sun, Nov 17, 2019 at 6:56 PM Jarek Steliga <[email protected]> > wrote: > >> Greg, >> >> Thank you. This means that I was wrong in squarely blaming a tiny little >> (barely visible) hole which I detected for the engine at times not being >> able to rev up beyond 2000 RMP. I simply thought the diaphragm kept the >> piston up for as long as the revs were higher and stayed there. My >> detective work is back to square one. >> >> >> Regards >> Jarek >> >> >> >> On Sat, 16 Nov 2019 at 22:49, Greg Wilson <[email protected]> wrote: >> >>> The diaphragm helps lifts the needle when you accelerate. Failed or >>> porous diaphragm will cause a lull in acceleration. I.e. If you slowly >>> increase the throttle very slowly you should still get full revs. >>> >>> Ditto if you don’t lubricate the centre tube, which can cause the carby >>> cylinder to bind when it’s lifting. >>> >>> My understanding anyway. >>> >>> >>> >>> >>> Greg Wilson >>> >>> >>> >>> >>> ---- On Sun, 17 Nov 2019 06:02:55 +1100 Jarek Steliga< >>> [email protected]> wrote ---- >>> >>> >>> >>> Hello, >>> >>> In case some of you had this problem, what were the symptoms? >>> >>> Thank you in anticipation >>> >>> Regards >>> Jarek >>> >>> >>> >>>
