Stihl KM85 help

[Old WoodChip]

Ok I know this is an easy one for you guys, I have cured many hickups but this one has me stuck and I need to get it running right to finish off a hedge urgent.

 

My problem is my pole hedge cutter will start as normal, runs ok when cold then seems like it is being starved of fuel then gets a burst then staves then another short burst if you get what I mean. It is a constant fiddle with the throttle just to keep it running.

New plug new air filter and took the carb off and thoroughly cleaned that, taking apart washing and blowing out with airline. thinking this would work as it always has done, this time I am stuck.

 

Any ideas please:thumbup1: (not ideas like buying a new one:001_tt2:)

 

Thanks

[Jonesie]

Check for a split in the fuel line inside the tank and that the fuel filter isn't blocked.

[Old WoodChip]

Many thanks Jonesie, I think the filter is pretty new I would have changed it but the pipe is worth looking at, will do first light in the morning.

Thanks again ;-)

[Old WoodChip]

Took trhe pipe out & checked it all over, filter is new but emptied the tank to see how dirty it was but very clean.

Put is all back together and started as normal, great until you go to let it tick over and need to keep blipping the throttle to keep it running, even after adjusting the carb? with the tickover screw all the way it it still wont run on its own.

Arr your thinking the low mixture, I know! as you know there is only limited adjustment on the H needle which was ok, but the L needle was set as best I could to stop it cutting out.

Thinking back this is why I took the carb off and sprayed & blew it all out a few weeks ago, it ran nicely then at first but soon went back to the old ways.

Anyway, hedge was finished but now I have to sort out the motor, any ideas would be most welcome

Thanks

[spudulike]

Could be a blocked muffler or blocked spark arrestor - my brother had a Husqvarna pole cutter and had to split the muffler, remove the baffle plate, get it red hot to get rid of the carbon then opened up the holes and reasembled - has worked fine for a couple of years unlike the dealer who "fixed" it before me!

 

I usually strip the carb, check the orientation of the gaskets - often re-assembled in incorrect order, check the gauze filter in the top pumping section of the carb & clean, remove the H&L screw and blast some cleaner down the holes and re-assemble. It is worth pressure checking the carb, it is possible the needle valve is leaking. Also check the impulse line, if the pumping action of the crank to the carb is intermittant, it can cause some problems. Worth checking for carbon build up on the exhaust port and tightness of carb to cylinder.

 

There - that should keep you busy:thumbup:

Spud