Suzuki ay50 overheating

Need some help guys my sons got a suzuki ay50 with a 70cc kit on which is overheating first time it blew the head gasket and I couldn't find a replacement so just bought another 70cc kit got that all fitted I bought a new expansion tank as the cap wouldn't screw on tight I flushed the whole system out with a hose so no blockages and it's still overheating and blew another head gasket well I'm assuming it has coz I took the sparkplug out and when I kicked it over coolant was coming out of the spark plug hole any ideas?

 

water pump has failed not is not coping with the amount of water needed to cycle the closed loop cooling system ?

i would take a look at the water pump buddy if your overheating and blowing top end gaskets a lot

 

Ok I'll check that out. The waterpump does turn when you kick it over but is it possible that when it's running it could be slipping?

 

If it's the belt driven water pump, check the belt, it may be snapped or damaged.

 

I've ordered a new gasket and water pump. Anyone know the torque settings for the head bowls?

 

If they are M6 threaded bolts for the cylinder heads (most scooters are) I'd aim for about 15Nm (about 10 lb ft).

 

So Ivery checked the water pump and doesn't look to bad but I've ordered a new one to be on the safe side. Any other reasons why it might be over heating? I've looked for a valve to let the air out the system but can't find one but there is a bolt on the water pump cover and if you unscrew it coolant will come out could that be where you let the air out?

 

Your radiator will be above the cylinder head so I would remove the thermostat and fill the cylinder side from there. Once that is full, then move on to the radiator and squeeze the hoses to expel air as you fill the radiator. That way you have ensured that there is coolant either side of the thermostat and the majority of the air will be purged out. The rest will get purged out once the thermostat opens and the enging is up to temperature. If you have a header tank, you'll see the air bubble up through the tank.

 

Water pumps not belt driven.
It pushes into three holes on a flywheel behind the right hand engine cover.
If it's leaking it will drip out the bottom of the cover through the drain hole.
There is the possibility that the head has gone, cracked or warped and it's not sealing properly on the gasket on top of the cylinder, allowing water to enter on top of the piston, hence the water you found when you took the plug out.
Quite possible that you have water in the exhaust as well, which would confirm it from what I've found in the past.
I've had 2 of these as projects, loads of fun.
Not the fastest things in the world but still fun.

 

I know that some AY50 Katanas had Morini engines and some had Aprilia engines. The Aprilia version had a belt driven water pump IIRC that looked like a 'ladder belt'. It was similar to the water pump belts on Piaggios.

 

Oh yeah................I'd forgot that they had two engines for that scooter, thanks Merlin.

In that case then I shall add.....................the Morini engined water pump runs off the flywheel......................

 

Ok so I've bought another head gasket and a new water pump used the 2 bolts one on the head and the other at the water pump to release any air in the system my son rode it to school today which is only a mile away and on his way back guess what???? It overheated and blew another head gasket took spark plug out and water came out this scooter has my head battered arghhhhh

 

OK, you need to try this. get a sheet of glass and some fine wet and dry silicon carbide gritpaper. Lightly oil the gritpaper withsomething like WD-40, place it on the glass then take the cylinder head and gently sand the head on the gritpaper with a swirling pattern for a few seconds. Lift the head off, clean off the head and look for any sign of warps - if the head is warped, there will be areas where the head hasn't been sanded.

If that's OK, then remove the thermostat from the engine and check that it opens when you place it in hot water.

Your symptoms lead me to think that if there's no obvious signs of water leaking out under the bike when it's idling, then it can only be going out of the exhaust or be boiling in the cylinder because the thermostat is stuck shut.

 

I think you might be right before I read what you posted I put another gasket on an it lasted about an hour. I've replaced the water pump with a new one and I've put a bigger jet in I've gone from a 72 to a 82 and it was running and sounding fine. So will i sand the head flat or replace it with a new one?

 

Sand it first, if it happens again, replace it.
Had the same happen to me on my katana.

 

I'll give it a go. Got a canny collection of damaged head gaskets now haha they all break in exactly the same place.

 

"Breaking"?
Do they have a black or burnt mark around the break?