More old Hayterette. Carb.

[Potash123 26]

Obviously these always need a new diaphragm after a while. I split the carb from the tank. The diaphragm is crap ( part no 391681 ). There are two springs on this set up Model 92908. There are two plastic feeds that go into the

depths of the tank. They have hexagon intakes which appear to be made for a spanner. I need to thoroughly clean the carb, so do these plastic pipes detach from the carb. I need to locate any jets, pilot, main

etc. This Hayter runs if I pour clean fuel down the intake, then cuts out. Many thanks.

[Wristpin 400]

Those pick up pipes do pull out but so long as the fine mesh on the end of each one is not blocked it's not usually necessary to do so.

The only jet fits from the outside at right angles to the venturi , on older carbs the body of the jet screws in and on later ones it's a push fit held in place by a rubber washer and shaped metal washer washer.

When refitting the carb to the tank it is necessary to pre tension the diaphragm by leaving all the carb retaining  screws slightly loose and having hooked the diaphragm rod into the crank on the choke shaft, hold the choke butterfly open while tightening the screws. When the choke is released it should move smoothly to fully closed.

This is better explained with illustrations in the appropriate BS manual.

[Potash123 26]

Hi lads. I have fitted the new diaphragm as per the above, no issues fitting it. I am still not getting any fuel through to the combustion chamber at all, the plug is dry as a bone. I know the engine runs

as I poured petrol down the carb. This only worked once only, but it did run fine for a minute. Obviously a blockage somewhere ? Help please.

[Stormin 4,458]

  Not sure if this will help, but a neighbour was having trouble with his strimmer. Would only run for a minute or two, and only after priming it. I had a look at it for him and found the pick up and primer return pipes had come adrift and were lying in the tank bottom.

[Potash123 26]

Well I have soaked the carb in an ultra sonic bath, changed the diaphragm, spring etc. All assembled and I am back to square one. I have a spark, but absolutely no fuel getting to the combustion chamber. Bearing in mind this did start once by pouring fuel down the carb, this only happened once and I have tried several times. I am wondering if I have no suction on the inlet side ( worn out bore ) come you experts. 

Regards Colin

[Wristpin 400]

Tip the machine back on the handle bars and put a weight on them.

Disconnect and ground the plug lead  and then with a glove on bounce the disc against compression in the opposite direction to  the way it runs  (ie clockwise) . This fools the decompressor profile on the cam into allowing full compression.  You should get s pronounced bounce not just a soggy  stop .

No bounce?  remove the head and inspect the bore and if you have access to bore measuring gauges, measure and compare with the figures in the appropriate Briggs manual. Obviously this is best done on a dismantled engine but in-situ will give you a rough idea. If you have a set of new rings you can poke them down the bore and compare end gaps against spec.

Might just be valves.   Check gaps, remove, inspect and if necessary reface, recut the seats, lap and set gaps.