TC-102 has been working fine for 8 x 30 min trips since buying it and yet last week it wouldn't run under any power. It has started fine when cold each day, revved out OK in neutral, ran at idle OK for 5 mins, has plenty of water flow, but stalls when put in gear at ANY throttle. It is then hard to start hot, won't idle well, won't rev out in neutral, and won't run in gear.
I've checked for gearbox fouling, tried a new plug, new HT lead and connectors, fresh fuel at many ratios, checked points, cleaned out tank, carbie and fuel lines. It has good spark cold and hot - but no guts when fuel and spark ignite. Must be low compression I figure.
So I am now about to embark on a complete strip and rebuild. What areas causing a power loss should I be on the look out for? Leaking crankcase seal, leaking crank bearings, cracked head, crook piston and rings, anything else???
A 102 with no power when warm
Moderators: John@sos, charlesp, Charles uk, RickUK, Petergalileo
Ok, an update.
Got the power head all stripped down to the last piece (in about 1 hour with a shifter, 2 spanners, screwdriver, hammer!
I love their simplicity.... and no rusted-in bolts 
). But before removing the barrel from the crankcase there seemed to be compression leakage by the rings into the exhaust port
I also found the following:
Slightly sloppy big end
Slightly worn little end
Slightly worn rings (what should their end gap be in the cylinder before replacement?).
Slightly coked piston and combustion chamber but nothing too bad to have caused a problem.
Slightly sloppy crank bearings. May have been leaking out of casing.
Coil wire insulation worn through where it enters the points housing and was very close to shorting, but that would be odd only to partially short and only when warm.
Drive housing threaded studs may have allowed leaking from the crankcase, so will locktight upon reassembly.
Slightly pitted points contacts.
No cracks in block or head.
Hmmmmm, but I'm not sure not any one thing or the sum of all things found amounts to conclusive indications of the problem.
I will test the coil, fix the uninsulated wire and then reasseble to see if I may have fixed the problem. ?!?!?! Perhaps the mere THREAT of a major renovation may resolve such errant behaviours.
Got the power head all stripped down to the last piece (in about 1 hour with a shifter, 2 spanners, screwdriver, hammer!
I love their simplicity.... and no rusted-in bolts ). But before removing the barrel from the crankcase there seemed to be compression leakage by the rings into the exhaust port I also found the following:
Slightly sloppy big end
Slightly worn little end
Slightly worn rings (what should their end gap be in the cylinder before replacement?).
Slightly coked piston and combustion chamber but nothing too bad to have caused a problem.
Slightly sloppy crank bearings. May have been leaking out of casing.
Coil wire insulation worn through where it enters the points housing and was very close to shorting, but that would be odd only to partially short and only when warm.
Drive housing threaded studs may have allowed leaking from the crankcase, so will locktight upon reassembly.
Slightly pitted points contacts.
No cracks in block or head.
Hmmmmm, but I'm not sure not any one thing or the sum of all things found amounts to conclusive indications of the problem.
I will test the coil, fix the uninsulated wire and then reasseble to see if I may have fixed the problem. ?!?!?! Perhaps the mere THREAT of a major renovation may resolve such errant behaviours.
Threats can work well on Seagulls, especially when accompanied by abusive language. They do not work, however, on my M**in*r 3.3. If I utter the slightest hint of a threat something else breaks...
Seriously though, are you confident about the fuel and the filters?
Does the thing start up again after a few minutes?
Seriously though, are you confident about the fuel and the filters?
Does the thing start up again after a few minutes?
hi
Are you shure, there is nothing wrong in your gearbox, a lot of resistence here will heat up the engine. There is not a fishing line behind the prop ? what if you put in forward without a prop.?
Charles, I believe it is vital that we properly understand the personalities and idiosyncracies (note the derivation from the word idiot) of our machinery and that, yes, some motors do respond well to abuse and others act perversely to it.
I had previously used fresh fuel, drained and cleaned all fuel lines and blown out jets. The problem is I do not truly know which carbie jets are in fact in there - the early 10:1 or the later 25:1. Even after I got them out this morning. They are both so scratched from someone else's attempts that number are invisible. So I will buy a new set of 25:1 and then I will know I can run at 15 or 20:1 with safety and efficiency.
Erik, I did check the gearbox in and out of gear and no drag is there. Gear oil is fine and new anyway. And besides, this problem manifested one day after no even being out again. Came home with power, next week no power. Still a mystery.
But I've wanted to completely strip and inspect it since buying it anyway. I always like to know exactly what is inside the machines I run. And you never know what you might find that is ABOUT to breakdown - vis a vie the worn wire from my coil.
I had previously used fresh fuel, drained and cleaned all fuel lines and blown out jets. The problem is I do not truly know which carbie jets are in fact in there - the early 10:1 or the later 25:1. Even after I got them out this morning. They are both so scratched from someone else's attempts that number are invisible. So I will buy a new set of 25:1 and then I will know I can run at 15 or 20:1 with safety and efficiency.
Erik, I did check the gearbox in and out of gear and no drag is there. Gear oil is fine and new anyway. And besides, this problem manifested one day after no even being out again. Came home with power, next week no power. Still a mystery.
But I've wanted to completely strip and inspect it since buying it anyway. I always like to know exactly what is inside the machines I run. And you never know what you might find that is ABOUT to breakdown - vis a vie the worn wire from my coil.
102
Hi Swami.
Perhaps there is one change you made, you probably filled gasoline on, are you sure about the mixture, allthough I repaired motors for many years, never a Seagull, but I have read somewhere, on SOS, that one of the reasons for the big amount of oil, was to keep the cranck bearings "tight" , so if you run with less oil, you could get air in/out there, which means you wil run on an even leaner air/gasolin mix, and get a poor compression. And result is less power. But I really don't believe it, as you can start the engine. That's normally not the case.
Allso the oil is getting thinner when warm.
Perhaps there is one change you made, you probably filled gasoline on, are you sure about the mixture, allthough I repaired motors for many years, never a Seagull, but I have read somewhere, on SOS, that one of the reasons for the big amount of oil, was to keep the cranck bearings "tight" , so if you run with less oil, you could get air in/out there, which means you wil run on an even leaner air/gasolin mix, and get a poor compression. And result is less power. But I really don't believe it, as you can start the engine. That's normally not the case.
Allso the oil is getting thinner when warm.
Erik, In fact I merely started it with the same tank full I left it with after last stopping it, only 5 days before!
While stripping I found:
* - I suspect the crank case was leaking a bit through the bolt holding the outlet flange to the driveshaft
* - The float bowl was on the wrong side of the carbie to what the manual says it should be
* - The power jet was butchered and crooked
* - A worn points-to-coil wire in several places which was very close to earthing out
* - The coil axle wasn't properly fixed to its mounting magnets or properly earthed
* - There was a tiny insulator missing from the points plate pivot
So, I suspect it was most probably poor sparking all along, although it looked like it had a good spark with the plug out for a few pulls, with all those wiring probs it must have had a weak spark under load.
We shall see ...................
It doesn't run at all now as it is fully in pieces! In a day or two it will all be back together and better - I hope.charlesp wrote:How long does the motor run for before it stops? And does it fade away, does it misfire and then stop, or does it just cut out? When it runs does it run at full throttle?
While stripping I found:
* - I suspect the crank case was leaking a bit through the bolt holding the outlet flange to the driveshaft
* - The float bowl was on the wrong side of the carbie to what the manual says it should be
* - The power jet was butchered and crooked
* - A worn points-to-coil wire in several places which was very close to earthing out
* - The coil axle wasn't properly fixed to its mounting magnets or properly earthed
* - There was a tiny insulator missing from the points plate pivot
So, I suspect it was most probably poor sparking all along, although it looked like it had a good spark with the plug out for a few pulls, with all those wiring probs it must have had a weak spark under load.
We shall see ...................
why
why didn't you mension all that from the start?Swami wrote:Erik, In fact I merely started it with the same tank full I left it with after last stopping it, only 5 days before!
It doesn't run at all now as it is fully in pieces! In a day or two it will all be back together and better - I hope.charlesp wrote:How long does the motor run for before it stops? And does it fade away, does it misfire and then stop, or does it just cut out? When it runs does it run at full throttle?
While stripping I found:
* - I suspect the crank case was leaking a bit through the bolt holding the outlet flange to the driveshaft
* - The float bowl was on the wrong side of the carbie to what the manual says it should be
* - The power jet was butchered and crooked
* - A worn points-to-coil wire in several places which was very close to earthing out
* - The coil axle wasn't properly fixed to its mounting magnets or properly earthed
* - There was a tiny insulator missing from the points plate pivot
So, I suspect it was most probably poor sparking all along, although it looked like it had a good spark with the plug out for a few pulls, with all those wiring probs it must have had a weak spark under load.
We shall see ...................
Erik, I could only mention what I knew and/or suspected at the time! After dismantling it, I found some things I suspected and other things I had not previously known or suspected. But before doing that I had checked and discounted all the obvious PRE-dismantle possibilities like fuel and spark plug and HT lead and gearbox fouling - as my first post says.
And .... it had been starting and running fine on 16:1 fuel for 2 weeks anyway (I used 16:1 because I was unsure if the carbie jets were 10:1 or 25:1. 16:1 is half the difference!)
"Knowledge before conjecture"
Swami.
And .... it had been starting and running fine on 16:1 fuel for 2 weeks anyway (I used 16:1 because I was unsure if the carbie jets were 10:1 or 25:1. 16:1 is half the difference!)
"Knowledge before conjecture"
Swami.
just kiddingSwami wrote:Erik, I could only mention what I knew and/or suspected at the time! After dismantling it, I found some things I suspected and other things I had not previously known or suspected. But before doing that I had checked and discounted all the obvious PRE-dismantle possibilities like fuel and spark plug and HT lead and gearbox fouling - as my first post says.
And .... it had been starting and running fine on 16:1 fuel for 2 weeks anyway (I used 16:1 because I was unsure if the carbie jets were 10:1 or 25:1. 16:1 is half the difference!)
"Knowledge before conjecture"
Swami.