Author Topic: Husqvarna 120 Mark II bogs down and stops when revving  (Read 125 times)

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Offline klrman

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Husqvarna 120 Mark II bogs down and stops when revving
« on: September 10, 2020, 01:00:24 pm »
Husqvarna 120 Mark II all of a sudden won't rev after starting.  Idles fine but when I rev it the motor bogs down and then cuts out and after it cuts out I need to let it rest 10 minutes or so as it won't fire up again.  Replaced ignition coil, carburetor, spark plug, air filter, fuel filter and still the same problem.   So far I have not spent any money with replacing these parts except for fuel and air filter as I have another 120 mark II as backup and kept swapping parts in hopes I can locate the problem.  Adjusting the high and low rpm doesn't make any difference either.  Anything I could try or may have missed?  It's only one year old and has been great otherwise.    I use Amsoil SABER professinal oil and never had a problem with this oil in all my other chainsaws over the years.

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Offline Spike60

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #1 on: September 11, 2020, 06:50:35 am »
Sounds like a carb issue. Those carbs are notorious for going bad like that, so don't discount the possibility that the carb from the parts saw is also bad. Next thing I'd try is to take one of them apart and try cleaning it.
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Offline klrman

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #2 on: September 11, 2020, 01:37:22 pm »
Put the carb back on the original saw and it works perfect so it's not a carb issue.  Even threw a new carb on today and still the same problem, it's really hard to figure this one out, I'm really stumped and doesn't matter how long I search for, I can't seem to find any answer.

Offline Spike60

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #3 on: September 12, 2020, 05:09:44 am »
If you've confirmed the carb is OK, then you might have an air leak down low somewhere. Might take a can of carb spray or brake clean and try to find it by spraying it down by the crank and intake boot areas. Also a good idea to check the fuel line for a leak.
Husqvarna-Jonsered

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Offline klrman

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #4 on: September 12, 2020, 12:27:35 pm »
I replaced the fuel lines yesterday evening even though I could not see any holes or cracks, but the problem still persists.  The intake boot looks ok but I'll give it a closer look just in case thanks.   The strange thing is that sometimes it will run fine for about 2 minutes before bogging down when revving.  I even disconnected the two fuel lines that go to the prime bulb to bypass it and connect the hose directly to the carb as I never need the prime bubble for starting but that didn't make any difference either.  What I noticed today is that when it ran for about 2 minutes, smoke started coming out of the exhaust, so I checked the exhaust baffle and it's all clear so no problem there either. 

Offline Cut4fun .

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #5 on: September 13, 2020, 07:40:57 am »
Did you ever pull the muffler for a peek at piston and rings? 

Any type of pressure test yet or redneck checks for air leaks yet like mention above with starter fluid etc?  Will kill it instantly if you spray over a air leak.  Crank seals, etc etc check them all.
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Offline klrman

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #6 on: September 13, 2020, 12:43:16 pm »
Piston and rings look fine but I never did a pressure test, don't even know how so I am looking at a youtube video how to do that and will try it.  Any tips or pointers?

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Re: Husqvarna 120 Mark II bogs down and stops when revving
« Reply #7 on: September 14, 2020, 08:12:33 am »
You can just try the redneck spray way or get more into it with rubber block offs.  http://chainsawrepair.createaforum.com/stickys-of-how-to-basics/pressure-testing/msg44138/#msg44138
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