# sthil hs80



## madmower (Feb 6, 2007)

hi had this hedge trimmer brought in it will run fine in all directions till hot then
it splutters or will not rev at all? i have cleaned the carb put new gaskets either side of the carb i have checked for intermittent spark when hot this is ok
i am at a loss as to what the problem is?
any help greatly appreciated
bill


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## geogrubb (Jul 28, 2006)

Sounds like the spark arrestor could be clogged. Remove the muffler and clean the spark arrestor, hopefuly that will take care of it. Have a good one. Geo


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## pyro_maniac69 (Aug 12, 2007)

check you rocmpression, if its low enough when the motor is getting hot, its expanding enough to lose enough compression that it doesn't have enough to run anymore


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## hankster (Jan 1, 1998)

Could also be a faulty ign. module that is intermittent when hot.


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## madmower (Feb 6, 2007)

hi 
i tried the mufler it was cloged up a bit this i hope will clear up the problem but why would this only afect the hedge trimmer when hot?
i have also checked the ignition this is ok i have been told it may be a crank case leak causing the problem now have to see if it come back with the same fault?

bill


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## pyro_maniac69 (Aug 12, 2007)

what do you have for compression?


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## madmower (Feb 6, 2007)

110 to 140 psi
bill


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## pyro_maniac69 (Aug 12, 2007)

any scratches in the cylinder?


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## repair_guy (May 9, 2004)

Your hedge trimmer has an electronic ignition modual in it.And as hankster had indected, intermittent to no spark at all when hot is a Symptom cauced by the ignition coil going bad.And this is the only warning the engine will give before it quits working all together.Nothing else will causes this.


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## madmower (Feb 6, 2007)

the engine runs fine it dos not cut out when hot it will tick over fine just will not rev up espcaly if you tilt it so the muffeler is pinting down there is not a problen with it cutting out just not reving when hot also if i apply choke it will rev up when hot? THE CARB HAS HAD A FULL REBULD AND NEW GASKETS
i am at a loss as to what the problem is? posably crank case leak?

bill


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## repair_guy (May 9, 2004)

madmower said:


> the engine runs fine it dos not cut out when hot it will tick over fine just will not rev up espcaly if you tilt it so the muffeler is pinting down there is not a problen with it cutting out just not reving when hot also if i apply choke it will rev up when hot? THE CARB HAS HAD A FULL REBULD AND NEW GASKETS
> i am at a loss as to what the problem is? posably crank case leak?
> 
> bill


I it was the oil seals around the crankshaft it would be running wide open uncontrollably all the time, or wouldn’t crank at all. Depending on the wear of the seals.Sounds to me that since you can apply choke and it straightens out,plus if you tilt if towards the muffler that you have a fuel delivery problem.there is also a carb. diaphragm problem.May be one n the same.All of these 2-cycle carb.kits comes with enough parts to rebuild 2 or 3 types of the some model carubretor.Are you sure that when you rebuilt the carb.that you put the right fuel pump diaphragm in it.Did it match the old one,(with all the holes in the same places)?Is there any holes in the carb. body balcked by the diaphragm?And was the gasket and diaphragm put in in the right order?If so maybe you should soak the carb.in chem-dip for 30 or 40 minutes or so where the holes will all be eaten out clear


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## madmower (Feb 6, 2007)

sorry repair guy if i afened you and thank all of you for your help with this problem 

all the carb parts were mached like for like the carb was put in a ultrasonic cleaning tank for 1/2 hour the gaskets were orignal sthil parts there is no damage to the piston on either side muffler or inlet not a mark
but there do seam to be a slight weap of gray grase from just under the carb this is what made me think it was a crank case leak but as you guys are the pros i am only a learner trying to pick up some advice on how to fix this problem i will strip the carb down agin and re check all the diaphrams / gaskets just to make shore i have not made a mistake i will also put the carb body back in the ultrasonic tank and give this anothor go

hope this will sort out the problem as sthil uk can not help?

bill


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## repair_guy (May 9, 2004)

No you didn't afened me.Was just trying to get the font bigger ,as us older people could read easer.sorry......When I found out that I got it too big I couldn't change it.

Have a good day and I hope that you fix the problem


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## geogrubb (Jul 28, 2006)

Madmower;
You mention a full rebuild, if you replaced the metering arm I would suggest using the original(unless very worn) it has the proper height setting, this could be affecting the volume of fuel available to the engine. I am not familiar with Ultrasonic cleaners so I will suggest soaking the carb in a good bath type cleaner such as NAPA mac 6402 and then blowing out all holes, cracks and crevases with brake parts cleaner(it doesn't leave residue). Have a good one. Geo


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## madmower (Feb 6, 2007)

i have been to a local dealer and got a carb off a machine in good working order same problem works fine when cold but when hot will tick over but will not rev till i give it choke?

not even the dealer can help he has sugested getting the machine presure / vacuum tested

bill


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