adw

Ok, some clarification needed, the s pipe as you call it, which connection on the purge bulb, long or short? when you depress the bulb does it push easily? does the bulb re inflate normally?

Take the purge bulb out, depress it, whilst depressed stick your thumb on the short connector, let the purge go, it should not re inflate.

If you do a vac test on the purge connector and fuel is down out then is it not just an issue with the bulb itself??

As I made complete dogs dinner of this I will explain a bit better, if you have a remote purge bulb it will have two connections on the back, a long connection which is the pressure side, and a short connection which is the suction side, so when the bulb is depressed a pressure is caused, as the bulb re inflates it creates a suction, there will also be a non return valve in the bulb so as to stop pressure down the suction side, there may also be a non return valve in the carb, so the short suction connector goes to the carb, this will be the connection closest to the metering side of the carb, this will draw fuel from the metering chamber into the bulb, when the bulb is depressed the fuel in the bulb is sent back to the fuel tank. so back to the original question why does it not purge, fuel filter in the tank blocked fuel screen in the carb blocked fuel hose kinked or split purge bulb faulty, non return valve stuck, or pin hole in bulb pipes incorrectly connected inlet needle stuck non return valve in main jet faulty metering diaphragm split.

Sorry NOT going to hold vacuum.

That is the purge connection so it’s going to hold a vacuum , the purge bulb pulls fuel from here, into the bulb and pushes back to tank, the carb has a compensator not an accelerator pump.

No problem fitting a non g flywheel, so as been said you may have sheared the flywheel key again, when you say rebuild what other parts have you fitted?

As a Briggs master technician ( I can see your impressed Steve ) you use a leak down tester to check valve leakage, cylinder and piston wear etc. check it out it’s a good bit of kit.

Leak down test will give you a good idea of the health of the engine internals.

So here we have good and bad.

Sorry I got the carb settings round the wrong way, L = 1 3/4 and H = 1 1/4 sorry I had a moment. I can take some pictures of the cylinder and manifold if it helps.

You can look from the r/h side between the covers, you will see the the back of the cylinder, you should not see a gap where the manifold is not fitting tight to the cylinder, just measure the distance between x torq ports on the original cylinder and compare with the new one, the impulse tube runs from the top of the carb to a connection on the inlet manifold.

The K760 is very bullet proof so there has to be some fairly obvious wrong with it, so to start, look at where the alloy inlet manifold connects to the back of the cylinder, it hooks under a plate on the back of the cylinder, there should be no gaps here it should fit and seal firmly on the cylinder, next make sure the impulse hose is connected, next have you fitted a genuine metering diaphragm? the after market ones do not have the additional hole to feed the compensator, next the rubber gasket between carb and air filter box, is it in good condition and aligned correctly? next did you fit the piston the right way round? this is very important as this saw has a ex torque cylinder, next if this is an after market cylinder make sure you have the correct inlet manifold because the cylinder ports were widened on the latter cylinder, carb settings are L 11/4 H1 3/4

I must confess I have not seen many big end bearings, plenty of main bearings though, these saws really suffer with the flywheel side seal leaking like a hole in a bucket, could this have been a factor in this failure?

The Husqvarna back pack blowers are from zenoah Japan, good engines but as with all this type of machine, cables and plastic shoot wear and tear, can’t really comment on the Stihl machines.