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Author Topic: gv250 efi engine compression reading?  (Read 383 times)

shana467

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gv250 efi engine compression reading?
« on: June 13, 2017, 10:15:15 PM »

Does anyone know what the engine compression readings are for 2010 Hyosung Gv 250 efi. My bike will not start so I have to take these readings from a cold engine. Besides attaching the gauge to each engine and hitting the start button, is there anything thing else i need to do to get accurate reading?
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mrcrum

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Re: gv250 efi engine compression reading?
« Reply #1 on: August 17, 2017, 02:00:14 AM »

My sons reads about 145 psi for each cylinder.  I would cycle it at least 5 times to get a more accurate reading.  If you find you have low compression you can remove the gauge and squirt a little oil into the cylinder.  If the compression goes up considerably, you can assume it's probably the rings.  If not remove the valve covers and check to see that the valves are coming all the way back up after the cam lobe goes by to see if you might have a bent valve.  Then you can remove the carbs and exhaust and squirt some oil on top of the exhaust valves and then the intake valves and see if that raises the compression.  The only thing I can think of after that is to remove the head to figure out the problem.  If you have good compression you're left with fuel or spark.
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Dojy_biker

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Re: gv250 efi engine compression reading?
« Reply #2 on: August 18, 2017, 12:57:47 AM »

in general you want 120psi or higher for decent running without problems

110 is a bit low but may still run

90 and below just wont work well or at all
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Joss

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Re: gv250 efi engine compression reading?
« Reply #3 on: August 18, 2017, 08:09:18 AM »

in general you want 120psi or higher for decent running without problems

110 is a bit low but may still run

90 and below just wont work well or at all

Thats exactly how I determine too.
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mrcrum

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Re: gv250 efi engine compression reading?
« Reply #4 on: August 20, 2017, 03:51:43 PM »

That sounds about right.  His friends Husky would only start with the foot crank and not the starter.  It turned out to be that his compression was about 90 psi and new rings and a cylinder hone fixed it so I'd agree.
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