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Hi all, I purchased this about two years ago and it has about fours hours use on it (dont like getting it dirty!), when i first got it new the engine sounded like it was missing, the Stihl dealer said all the four mix engines sounded like that and got another one out and sure enough it was the same but it does seam to have a good bit of power but when running it sounds like a old engine missing a lot, just wondered if this is really normal?, to the problem, using the hedge trimmer attachment and been using it for about twenty minuites and half a tank of fuel and it just cut out, started up again but cut out straight away, then it would not start. I left it for about ten minuites then opened the fuel tank cap and it sounded like there was a vacume of some sort, put the cap back on and away it went no problem, any ideas?. Also i have a old Hs74 hedge trimmer that i have a problem on but i posted it in the small engine and mower repair under Stihl hs 74 wont start, if anyone has any ideas on any of them i would love to hear them.

Has not cut out again but i have ordered the kit to set the valve clearance.

Set the valve clearances, one had a bit more clearance than other, while i was at it cleaned plug and checked air filter. All fine now, also now there is much less resistance when u pull the rope starter which i think is as it should be.

I Have heard lots of people say about the strange sound of the 4-mix engines. I'm sure yours is normal.

Clean the gas tank cap it needs to vent

(( racing is the only sport that you need two balls ))

Thanks for the replys, checked the fuel cap and it is ok, has not cut out since i did the valves. When i adjusted the valves i noticed the exhaust was rusty in places and it has not had much use. I am going to remove the exhaust and paint it, anyone have any tips on this?

Bootsy said:

Thanks for the replys, checked the fuel cap and it is ok, has not cut out since i did the valves. When i adjusted the valves i noticed the exhaust was rusty in places and it has not had much use. I am going to remove the exhaust and paint it, anyone have any tips on this?

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Don't paint it just will cause more problems later :thumbdown:

Carscw said:

Clean the gas tank cap it needs to vent

(( racing is the only sport that you need two balls ))

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This fuel tank has a pressure in it normally, there is/was a recall on the 4mix fuel caps, Stihl dealer needs the model and S/N to file a claim.
Was mowing a while back on a hot day and both my FS 90 Kombi trimmer and BR 600 back blower went into vapor lock during operation, must be a common characteristic of 4Mix engines and 10% ethanol mixed gasoline. Had to get out my 2 stroke backup units to finish the job.
Mad Mackie in CT

Hi all, thanks for the replys, after i adjusted the valves it has been fine but i cant see why adjusting the valves would of sorted it. A very good friend of mine has a Landscaping company and had to clear a very large area so i lent him my engine unit and it was used in 30 degrees for a long time and it was fine, he has 3 km130`s and 2 km90`s with all the bits to go on them. It was on his recomendation i bought mine. He also has a custome made hedge trimmer for the combi`s that is the Stihl hedge cutter with a very short shaft so when its attached to the motor its not that much longer than a normal hedge trimmer, I really like that and will try to talk him in to getting me one.

Spoke to soon, using it for about a hour and the tank got to about half full and it cut out, would not restart until i removed the fuel cap then replaced it, i contacted Stihl and asked if there was a recall on the fuel caps on this model but was told no, also asked about vapour lock but was told that the 4 mix engines dont have that problem. Phoned my dealer and asked him the same but he said the same as Stihl. It seams to me it is some thing to do with the fuel cap so was thinking of (if it fits) putting my fuel cap from my Hs74 on it and give it a try. What do you think?