- Joined
- Apr 22, 2020
- Messages
- 3,109
First gotta say my P11 motor is not stock, so my observations below will not apply to basic proper P11 restorations.
I have a cNw reed breather on the back of the timing case of my P11. (See **note at the end of this post if wondering why.) I believe the standard installation recommendation with the cNw breather on the back of the crank case was to block off the cam timed breather, so I did even though that is not where I installed the cNw breather. Never had a problem with it on the back of the timing case until I went out and started riding like a teenager and passing cars on mountain roads. Told myself I wouldn't do that again and see if I could extend the tire life, but old habits die hard. Anywho, the cylinder base gasket started to weep a little due to the thrashing, not pour out oil, just a little weep. So because I am not a fan of leaks, I got to thinking maybe I should hook that timed breather up and see if I get better crank case pressure evacuation. I have not had a chance to run the motor up to excessive RPM for any extended period of time, but there was another positive side effect I felt immediately. The motor is about 50% easier to kick over stone cold with the timed breather hooked up. I'm leaving it hooked up because of that feature alone.
Breather plumbing is currently T'd together about 8 inches before entering the oil tank. I plan to find a tight angle Y connector and connect the plumbing together just before the oil tank so there is no chance of any weird backward pressure pulses against the reed valve with the two pressure sources coming together too soon in the plumbing circuit. May not even be a real issue, but still want to do it that way.
Point is having both the breathers hooked up lets the motor breath better if using a breather off the timing case. I will update this thread if I notice any negative performance issues at higher RPM. My motor will wind up higher than is recommended for a stock motor. It still pulls even if not making any additional HP. 85mph in 3rd is 7000 RPM with my gearing and my motor was still pulling before shifting into 4th the day I did that. I don't do that regularly, because I doubt it would last that long doing it, but had to try it once to see how it sounded and felt. Kind of intoxicating, but best avoided on the street.
One thing I have not tried is having only the timed breather hooked up. It might be sufficient for the engine. It was for the motor when it was bone stock.
**Only reason I had installed the cNw breather on the back of the timing case in the first place is because I had a 2S cam in the motor previously that was not designed to support the timed breather.
I have a cNw reed breather on the back of the timing case of my P11. (See **note at the end of this post if wondering why.) I believe the standard installation recommendation with the cNw breather on the back of the crank case was to block off the cam timed breather, so I did even though that is not where I installed the cNw breather. Never had a problem with it on the back of the timing case until I went out and started riding like a teenager and passing cars on mountain roads. Told myself I wouldn't do that again and see if I could extend the tire life, but old habits die hard. Anywho, the cylinder base gasket started to weep a little due to the thrashing, not pour out oil, just a little weep. So because I am not a fan of leaks, I got to thinking maybe I should hook that timed breather up and see if I get better crank case pressure evacuation. I have not had a chance to run the motor up to excessive RPM for any extended period of time, but there was another positive side effect I felt immediately. The motor is about 50% easier to kick over stone cold with the timed breather hooked up. I'm leaving it hooked up because of that feature alone.
Breather plumbing is currently T'd together about 8 inches before entering the oil tank. I plan to find a tight angle Y connector and connect the plumbing together just before the oil tank so there is no chance of any weird backward pressure pulses against the reed valve with the two pressure sources coming together too soon in the plumbing circuit. May not even be a real issue, but still want to do it that way.
Point is having both the breathers hooked up lets the motor breath better if using a breather off the timing case. I will update this thread if I notice any negative performance issues at higher RPM. My motor will wind up higher than is recommended for a stock motor. It still pulls even if not making any additional HP. 85mph in 3rd is 7000 RPM with my gearing and my motor was still pulling before shifting into 4th the day I did that. I don't do that regularly, because I doubt it would last that long doing it, but had to try it once to see how it sounded and felt. Kind of intoxicating, but best avoided on the street.
One thing I have not tried is having only the timed breather hooked up. It might be sufficient for the engine. It was for the motor when it was bone stock.
**Only reason I had installed the cNw breather on the back of the timing case in the first place is because I had a 2S cam in the motor previously that was not designed to support the timed breather.