Author Topic: GX390.... again...  (Read 8974 times)

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Offline Tom Price

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GX390.... again...
« on: April 19, 2011, 10:35:00 am »
Ok, The motor is together and installed and I was not there when my buddy fired it last night but he called to say that they had it running and then shut it off.  Then it got hard to pull and backfired so hard throught the carb it blew the choke butterfly out of it.  Going to look tonight but just looking for some possibilities to look for... timing, valve's not adjusted right?  These are very new to me so I'm still learning as I go but you have to somehow.
#5 Tom Price
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Offline Squidd

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Re: GX390.... again...
« Reply #1 on: April 19, 2011, 10:49:31 am »
Flywheel key
Randy Stys
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Offline Tom Price

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Re: GX390.... again...
« Reply #2 on: April 19, 2011, 11:36:26 am »
Flywheel key

Thinking that too.  Since I have never messed with an OHV till now I'm wondering if I adjusted the valves wrong possibly...
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Offline Squidd

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Re: GX390.... again...
« Reply #3 on: April 19, 2011, 12:01:04 pm »
Usually when it runs...and then it don't....something changed moved or broke...

If it was out of adjustment, it never would have started or run well to begin with..
Randy Stys
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Offline Jeremy_Conley

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Re: GX390.... again...
« Reply #4 on: April 19, 2011, 12:50:03 pm »
I have to agree with squidd on this one, sounds like the flywheel key. Mine turned over so hard last year that it would actually rip the pull cord out of your hands and send ya to the first aid kit, lol...
Conley Mowersports
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Offline Tom Price

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Re: GX390.... again...
« Reply #5 on: April 19, 2011, 03:57:44 pm »
I have to agree with squidd on this one, sounds like the flywheel key. Mine turned over so hard last year that it would actually rip the pull cord out of your hands and send ya to the first aid kit, lol...

Did you have problems with yours shearing flywheel keys?  He said it was a you know what to start lol
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Offline amr5080

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Re: GX390.... again...
« Reply #6 on: April 19, 2011, 05:20:02 pm »
Check the rocker arms. I had a similar issue and one of the arms was broke...
Aaron Rupert
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Offline Jeremy_Conley

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Re: GX390.... again...
« Reply #7 on: April 20, 2011, 01:37:38 am »
I never had any issues with the key, not sure why it was so hard to pull. Actually I just put mine back together last weekend and had a similar issue. It started fine the first time then I shut it off and re-adjusted the valves then it wouldn't start and back fired. Ended up being the intake valve was to tight and holding the valve open pushing the fuel back out of carb.
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Offline Tom Price

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Re: GX390.... again...
« Reply #8 on: April 20, 2011, 01:22:34 pm »
I never had any issues with the key, not sure why it was so hard to pull. Actually I just put mine back together last weekend and had a similar issue. It started fine the first time then I shut it off and re-adjusted the valves then it wouldn't start and back fired. Ended up being the intake valve was to tight and holding the valve open pushing the fuel back out of carb.

What kind of lash do you run?  Is it a stock cam?  AGK says .004 on the lash so thats what I set it at.
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Offline Jeremy_Conley

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Re: GX390.... again...
« Reply #9 on: April 22, 2011, 01:31:36 am »
Stock cam. I run mine at 3 on intake and 5 on exhaust
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Offline GRUBDIGGER

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Re: GX390.... again...
« Reply #10 on: April 22, 2011, 04:19:51 pm »
.004 ON BOTH AND RECHECK THE LASH. IF OK, THEN CHECK THE FLYWHEEL KEY. IF THATS ALL GOOD CHECK TO SEE IF 1 OF THE VALVE SEATS FELL OUT.
JOHN HERRING
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