Silver Century 75 stopping during run
Posted: Tue Oct 24, 2017 10:36 am
Hello everybody,
I'm new on this forum and would like to know if anyone has an idea on what might be the problem with my ESC 2231 AAO Silver Century 75. I bought it two months ago, cleaned the carb, fresh fuel in the tank and off we went. It was performing well except that very little cooling water was coming out of the cylinder. It would, though, run well for long periods. Lastly there would come no water anymore but a sort of steam so I decided to give the Seagull a thorough service. Stripped it down totally except the crankcase, crankshaft and con-rod, as there was no evident play anywhere in these parts. The waterways in the cylinder were all full of rust etc, cleaned them out as good as I could. The cylinder bore, piston and rings were almost as new, honing marks could still be seen in the bore. As I had no new head gasket I heated the old one cherry red and dipped it into water to get it soft again. Done this countless times on other copper and aluminium gaskets, has worked well. Checked the straightness of head and cylinder top. Used instant gasket sealer on both sides of head gasket, but only for the waterways, not on top surface of the cylinder liner itself. I have bad experiences on using it there, from other engines. Assembled the whole thing, started first pull as it always does. After running it warm for a couple of times i re-tightened the head bolts, done this twice. Everything seems to be fine. Cooling water flow is good even at tick-over.
Now the problem: after running it om my boat for 30 to 40 minutes it stops. It doesn't stop in a way that the spark would die out, suddenly, like in half a second, it stops in a way that takes from one to two seconds, if you understand what I mean. Difficult to describe.
If I immediately after the stop turn myself to the engine, pull the rope (has a recoil starter) it starts first pull and works for 10 minutes. Good compression felt on the rope. Then stop, start, runs in 10 min periods as long as I want to. I have the opinion that if the fault would be an electric one, it would start only after cooling down. (the ESC has pointless ignition)
I have tried with another tank, from a moped,hanging from a lenght of tubing with petrol cap removed. Same symptoms, no help. Have cleaned the carb several times and tried an in-line filter on the petrol hose.
Have tried other plugs with different heat ranges.
Head gasket? As mentioned I softened it and have re-tightened the head bolts. Tried spraying a soapy solution all over the engine to find out if there was a leak. No bubbles visible. Leaking into the water jacket? I attached a piece of hose to the water outlet, other end to a clean 10 liters water can, covered the mouth of the can with a rag so that just a little air could get out. Run it long enough to half-fill the can, stopped and sniffed but no smell of exhaust fumes could be felt. Kept the water in the can for a week, no oily deposits would float, as there would be if exhaust fumes from a leaking head gasket would go into the cooling water.
The symptoms are the same if running at half throttle.
Could it be the pointless ignition module? Why does it re-start, then, without cooling? If there would be a leak in the crankcase that would appear after 30 minutes running why does it re-start? I mean, after stopping and re-start there's only five seconds.
Also remember that it was working well with the waterways all clogged. What have I done wrong with the re-build?
In my opinion a two-stroke needs fuel, air, top-end and crankcase compression plus a good spark for running. These are all there.
Regards,
Janne Petersen
Helsinki, Finland
I'm new on this forum and would like to know if anyone has an idea on what might be the problem with my ESC 2231 AAO Silver Century 75. I bought it two months ago, cleaned the carb, fresh fuel in the tank and off we went. It was performing well except that very little cooling water was coming out of the cylinder. It would, though, run well for long periods. Lastly there would come no water anymore but a sort of steam so I decided to give the Seagull a thorough service. Stripped it down totally except the crankcase, crankshaft and con-rod, as there was no evident play anywhere in these parts. The waterways in the cylinder were all full of rust etc, cleaned them out as good as I could. The cylinder bore, piston and rings were almost as new, honing marks could still be seen in the bore. As I had no new head gasket I heated the old one cherry red and dipped it into water to get it soft again. Done this countless times on other copper and aluminium gaskets, has worked well. Checked the straightness of head and cylinder top. Used instant gasket sealer on both sides of head gasket, but only for the waterways, not on top surface of the cylinder liner itself. I have bad experiences on using it there, from other engines. Assembled the whole thing, started first pull as it always does. After running it warm for a couple of times i re-tightened the head bolts, done this twice. Everything seems to be fine. Cooling water flow is good even at tick-over.
Now the problem: after running it om my boat for 30 to 40 minutes it stops. It doesn't stop in a way that the spark would die out, suddenly, like in half a second, it stops in a way that takes from one to two seconds, if you understand what I mean. Difficult to describe.
If I immediately after the stop turn myself to the engine, pull the rope (has a recoil starter) it starts first pull and works for 10 minutes. Good compression felt on the rope. Then stop, start, runs in 10 min periods as long as I want to. I have the opinion that if the fault would be an electric one, it would start only after cooling down. (the ESC has pointless ignition)
I have tried with another tank, from a moped,hanging from a lenght of tubing with petrol cap removed. Same symptoms, no help. Have cleaned the carb several times and tried an in-line filter on the petrol hose.
Have tried other plugs with different heat ranges.
Head gasket? As mentioned I softened it and have re-tightened the head bolts. Tried spraying a soapy solution all over the engine to find out if there was a leak. No bubbles visible. Leaking into the water jacket? I attached a piece of hose to the water outlet, other end to a clean 10 liters water can, covered the mouth of the can with a rag so that just a little air could get out. Run it long enough to half-fill the can, stopped and sniffed but no smell of exhaust fumes could be felt. Kept the water in the can for a week, no oily deposits would float, as there would be if exhaust fumes from a leaking head gasket would go into the cooling water.
The symptoms are the same if running at half throttle.
Could it be the pointless ignition module? Why does it re-start, then, without cooling? If there would be a leak in the crankcase that would appear after 30 minutes running why does it re-start? I mean, after stopping and re-start there's only five seconds.
Also remember that it was working well with the waterways all clogged. What have I done wrong with the re-build?
In my opinion a two-stroke needs fuel, air, top-end and crankcase compression plus a good spark for running. These are all there.
Regards,
Janne Petersen
Helsinki, Finland