My Sq 4 keeps giving me trouble. I'm beginning to believe she has something against me.
After blowing the Otto head gaskets, I am using copper ones as I couldn't find new Ottos.
After reassembling the head and torquing everything properly, she started easily, did the first heat cycle in the garage and retorqued again. Most nuts had lost some torque - maybe a flat had to be turned. Then I went off for the first ride. She ran perfectly for about 20 miles, engine running very smoothly, but then after a run where maybe I pushed her too hard, I felt a loss of power followed by a change in tone, and the gasket had blown again. After getting back and cooling down, there was indeed a noticeable torque loss on most nuts.
So the head came off again and I started anew. Triple checked everything and one thing I noticed was that the holes on the gaskets for the head bolts were catching on some of the bolts maybe preventing the gasket from laying completely flat. I opened up the holes a bit and checked gaskets would fit completely flat, everything spotlessly clean, gaskets anealed, and everything reassembled, retorqued, valve gaps set, etc.
The first start was again easy, and I let her idle for about 10 min before shutting off. The next day torque was rechecked, and this time only one or two nuts needed a slight tightening and a slight adjustment on the valve gaps. Already a good sign. Second heat cycle and this time only one nut had to be tightened a tiny bit. Valve gaps rechecked, but no adjustment was necessary So today I wanted to go for the first ride, just around the block and taking it very easy, and this is when the new troubles started.
She was much harder to start, but she did, however she didn't seem to want to idle when I pushed the bi starter in. As I put her into gear and tried to drive off, she didn't want to go and wanted to stall. I managed to take off eventually, but the engine did not pick up and died after a bit. Restarting was then uncharacteristicaly harder and I barely managed to go up and down the road. She had no power, the engine wouldn't pick up, ran erratically and wanted to stall. Playing with the bi starter in and out, did not really make it better or worse. Parked in neutral in front of the garage she would idle, but not as steadily as before, and strated dying if the bi starter was pushed all the way in. I rechecked the pilot screw, but it was where it always had been at about two turns out. I could keep the engine running, but only with a bit of throttle or the bi-started a bit out.
So it seems to me like the symptoms of:
1. Not enough petrol
2. timing off or not advancing
3. valve timing
Fuel flow from the tank seems fine - checked. I will check the carburetter again as it was on and off several times to get to those two impossible nuts under the manifold. Maybe some debris got in there. And also a look at the petrol tap. Before you ask the petrol tank is half full.
The timing seems strange as I didn't touch the distributor or anything that could affect the timing. Unless the advance mechanism stopped working for some reason, but this seems unlikely. I do get a good fat spark on all 4 plugs.
As far as valve timing, the only thing I can think of would be the tappets. If during assembly I did something wrong and one is not sitting properly on its guide cup. But if it was so, would she even start and idle?
Anyway, maybe you have some other ideas and suggestions. Hopefully I'm just missing something stupid.