Hi All!
So last week we got the mighty 750 'Atom' running. Not very well, but the bloody thing ran which we were absolutely elated by. Video here, please excuse the lossy sound compression:
https://www.dropbox.com/s/ztr1yomlxab37s...1.mp4?dl=0
Bad Compression
So talking of compression, fast forward to this week; The father and I were bolting the clutch onto the engine tonight. All was going swimmingly until we started torquing the bolts on the clutch. When moving the engine to get prime wrench access, i noticed a distinct 'hissing' noise when the engine was under compression. As soon as the hissing noise stopped (~3 seconds) the compression was no longer there. Leakage...
We then performed a plugs-out, 12v starter, cold compression test. I know they're supposed to be performed warm, but wanted some indication of a fault. The results in PSI: 65, 65, 65, 70. Damn. We tried adding a spoonful of oil, and the readings came up +5 PSI. I presume a freshly built engine should be in the 90~110PSI region?
The engine was fully re-built around 35 years ago with +040 pistons and has been in storage ever since. I did notice that the cylinder bores were a little glossy but had faith that it would just work. Do you guys think it needs a full overhaul again?
Coolant Leakage
I also tried a simple water loop to ensure the engine was water tight and boy did it fail! Literally all 3 coolant manifold bolts/nut leaked! Is there any magic cure to this short of PTFE tape on the threads?
Many thanks for any input!
So last week we got the mighty 750 'Atom' running. Not very well, but the bloody thing ran which we were absolutely elated by. Video here, please excuse the lossy sound compression:
https://www.dropbox.com/s/ztr1yomlxab37s...1.mp4?dl=0
Bad Compression
So talking of compression, fast forward to this week; The father and I were bolting the clutch onto the engine tonight. All was going swimmingly until we started torquing the bolts on the clutch. When moving the engine to get prime wrench access, i noticed a distinct 'hissing' noise when the engine was under compression. As soon as the hissing noise stopped (~3 seconds) the compression was no longer there. Leakage...
We then performed a plugs-out, 12v starter, cold compression test. I know they're supposed to be performed warm, but wanted some indication of a fault. The results in PSI: 65, 65, 65, 70. Damn. We tried adding a spoonful of oil, and the readings came up +5 PSI. I presume a freshly built engine should be in the 90~110PSI region?
The engine was fully re-built around 35 years ago with +040 pistons and has been in storage ever since. I did notice that the cylinder bores were a little glossy but had faith that it would just work. Do you guys think it needs a full overhaul again?
Coolant Leakage
I also tried a simple water loop to ensure the engine was water tight and boy did it fail! Literally all 3 coolant manifold bolts/nut leaked! Is there any magic cure to this short of PTFE tape on the threads?
Many thanks for any input!