Just to answer a few questions.
The oil pump was used and worked fine on my other A10 I only changed it to fit a rev counter to it, so I know the pump is good.
I have swapped PRV's with my other bike so I know thats good as thats done 10'000 miles since I built it.
All of the flexible oil pipes are new and have also been replaced again with new. The rocker feed pipe is also new and has also been replaced with new again. The only time the rocker pipe blew off is when I put my finger over the return in the tank cos it was bursting out all over the place.
On tickover the oil just returns a bit quick but as soon as you blip the throttle is when it spurts like a demon.
So this is my logic.
Firstly the feed must be fine or it would not return like a lunatic it would splutter as the return side of the pump is bigger than the feed anyway.
Now as it insists on pumping out of the breather in the crankcase and its returning like a lunatic then there simply must be too much pressure in the crankcase.
My next thought is the only thing that relieves that pressure in the engine is the PRV. Now if I know the valve itself is good so then my logic tells me that the oil ways from the PRV must be blocked thereby not relieving the pressure.
What else can it be?
There is one tiny oil way from the PRV that is drilled thru the crankcase (its blocked at the front after the drilling) which must be where the PRV directs the oil when it relieves the pressure. I obviously blew this out when I built the engine but all I can think is that when the engine gets warm that this gets blocked or partially blocked causing the problem.
Every other part of the engine barrels, head, rocker box, camshaft etc. except for the crankcases I have used in the past. Obviously the big ends, and bearings are all new but they wont be causing this.
The oil pipes, the first bit from the engine is solid and was well cleaned and there are only a couple of inches of flexible oil pipe (all renewed twice now) the oil tank has been off 3 times and there is no way there is a blockage in there, trust me I have mini brushes etc and made sure that was clear AGAIN. I do not have an oil filter on the return side the oil system is totally standard with no modifications of any type except for the rocker feed being mainly rubber instead of 99% copper pipe but thats not blocked cos if I take the pipe off at the rocker box end the oil comes out quite happily.
In my eyes, obviously I have been trying to cure this on and off for over a year so have done a lot more than I have written on this article, all thats left is a complete engine strip and major inspection of the crankcases.
What choice do I have? If anybody has a better one then I will be more than willing to listen cos its already been line bored etc. so I dont really want to change crankcases if I can avoid it.
For those who think I might be a total thicko (you wont be the first to think it by the way
) I got my first A10, this one as it happens, when I was 16. I am now nearly 64 so not a newbie in anybodies eyes and I can virtually build them in my sleep. Maybe thats where I went wrong on this one, dozed off and put the oil pump on upside down or something, and yes I do know thats impossible. Fitting the oil pump upside down I mean not me dozing off.
The most infuriating thing of the lot is that the damned thing is oil tight, even the rocker box and now I have to strip the damned thing apart
How on earth does one get an A10 oil tight when the pressure is too high? I cant normally get them 100% oil tight when the pressure is normal.