Another dodgy machine

[topchippyles]

2 hours ago, Stere said:

Sounds like something that Scot window cleaning bloke would do. 🙂

 

Or maybe he would use a recip saw

That was one clown of a bloke 🤪

[Deafhead]

16 hours ago, spudulike said:

Allen Scythe even....good call though! The Grim Reaper of long grass.

I've still got muscles on my muscles from using those years ago.

Edited July 2, 2021 by Deafhead

[Jack.P]

I cleaned and adjusted the carb on this then ran it for 5 hrs non stop .it worked better for the first 2 hrs then the speeds kept changing again and it got more shakey after a while .seems to go from fast then too slow which then makes it hard to start ,i was going to change the carb but not for nearly 100 quid for a Stihl one 

also couldn’t work out how the high and low works with no turn screw? Only the LA can be adjusted ,seems very daft

Edited July 5, 2021 by Jack.P

[spudulike]

The carb should have an adjustable H and L screw. I have just looked at the KM91 IPL on the L&S website and it has the three normal screws.

The symptoms you have would appear to be lack of fuel. in this instance, if the diaphragms and carb gauze strainer are OK, I would check the fuel line, change the fuel filter and if the same, rev it up, turn the H screw anticlockwise until the engine is stifled and then turn it in again until it nearly cleans up but doesn't scream.

Put some pics up, the adjustment screws will probably be tamper proof hex type.

[Jack.P]

54 minutes ago, spudulike said:

The carb should have an adjustable H and L screw. I have just looked at the KM91 IPL on the L&S website and it has the three normal screws.

The symptoms you have would appear to be lack of fuel. in this instance, if the diaphragms and carb gauze strainer are OK, I would check the fuel line, change the fuel filter and if the same, rev it up, turn the H screw anticlockwise until the engine is stifled and then turn it in again until it nearly cleans up but doesn't scream.

Put some pics up, the adjustment screws will probably be tamper proof hex type.

Just looked it does have a small hex type unlike chainsaws /hedge cutters .it had me confused as only a screwdriver came with it but it probably would have been done when serviced at shop .had read to loosely tighten both the H and L screw then undo both 1 and a quarter turn? I adjusted the idle when it warmed up so the cutting head was only just slowly turning on idle then after a few hours it then spins on full speed 

I got the most power out of a cheap machine once having them both set to the highest,it still lasted along time before the piston broke in 2 

[spudulike]

Probably Stihl Hexagonal screws, just get the correct driver and turn the H screw out 1/4 turn and try that for starters. It often brings the engine to life.

I am taking it the unit is faltering flat out and the idle is OK?

[Jack.P]

1 hour ago, spudulike said:

Probably Stihl Hexagonal screws, just get the correct driver and turn the H screw out 1/4 turn and try that for starters. It often brings the engine to life.

I am taking it the unit is faltering flat out and the idle is OK?

Thanks for the pointers , have set the idle a few times only to find it then goes back to going too fast .when its run for long periods flat out it seems much more of a problem

Did run better for the first 2 hours though after cleaning the carb

 

[Khriss]

10 hours ago, Jack.P said:

Thanks for the pointers , have set the idle a few times only to find it then goes back to going too fast .when its run for long periods flat out it seems much more of a problem

Did run better for the first 2 hours though after cleaning the carb

 

This is starting to sound like an air leak somewhere 🤔  K

[Jack.P]

9 hours ago, Khriss said:

This is starting to sound like an air leak somewhere 🤔  K

Possibly ,i was back on the job today and  ran it for another 6 hrs .sometimes it runs better for no apparent reason. there was some thicker matted grass which it bogged down a bit with but not too bad other than that .it runs better with a few squirts of carb cleaner through the air intake 

[spudulike]

I am taking that this machine is perhaps 1-2 years old, on a machine this age, an air leak is very unusual.

 

The unstable idle, first thing I would check when the revs increase and won't go back to the idle first set is that the carb is shutting off as it should. Yo may be releasing the throttle lever but the cable may be routed incorrectly and holding the carb open. I do this by pushing on the arm the cable is connected to so the carb throttle valve is pushed completely shut as you may have some issue with the cable that holds it open. If the revs drop back to normal, you have found your issue.

 

If the revs still race, it may be a lean L screw, sometimes when they are set a bit lean, the idle becomes a bit unstable - manufacturers like them lean as they can certify their equipment as EPA compliant! 

Much comes back to getting the carb set by someone who knows what they are doing, 1/4 turn out on the L and H screw may sort your issues. A lean L screw will make it more difficult to start, be more unstable on idle and may bog if you give it a fistful of revs from idle. A lean H screw may make the engine falter and bog instead of revving out cleanly.

 

How is your air filter? If it is a bit blocked, this can give some issues. The carb colour can give you some interesting info. If the machine is low hours, it is unlikely to have any serious issues. One KM94 I did had your symptoms and a new fuel filter fixed it after a carb tune did very little!