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Joined: Apr 2011
Posts: 5
Novice
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hey fellas,i got this victa mower a few years back and it has slowly been getting more gutless ,its one of those corvette mowers with the honda 4 stroke,i think i may have dusted it although it doesn't blow smoke ,any way what sort of compression should these have ,i put my trusty and accurate gauge in it and 75 psi is the best i can manage after about half a dozen pulls on the starter cord
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Joined: Oct 2010
Posts: 1,819 Likes: 6
Junior Technician
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Not sure what decompression system a Honda has but i am pretty sure that how well it works will be directly related to the valve clearances being set correctly. 75psi sounds reasonable for a motor with a decompressor.
I also seem to recall something about hondas needing the Govenor system adjusted.
If you got it a 'few years back' and it has not seen a service person that knows what they are doing in all that time, of any mower would expect what you describe.
The govenor info could be found on here, im sure someone who knows will post up. The valve clearances are straight forward, if you own a trusty Compression guage im sure you are more than capable of Googling the clearances and getting some tools out.
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Joined: Jan 2009
Posts: 6,926 Likes: 10
Pushrod Honda preferrer
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You haven't told us what the Honda model number for your engine is. Your pressure reading is almost exactly in the center of the range of values specified for a GXV120, the engine used on the HR194 for example. However if you have a side valve Honda, which does not have a decompressor, this has no relevance. If your engine is overhead valve and it does not blow blue smoke, it sounds as if it does not have a serious problem with loss of compression. The first thing to check if you believe it is losing power, is the adjustment of the governor. If the governor friction clamp has slipped the engine will not be achieving its proper maximum speed or power. Adjusting the governor to ensure it delivers its proper maximum speed is a specified service operation from the owner manual, required once each year. You can find out how to do it from this thread: https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=32261#Post32261You should also adjust the tappets once each year.
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Joe Carroll
Unregistered
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I would lay money on it being a gcv160. I am not sure what the compression reading should be, but he sure to have correct tappet adjustment or you will lose pressure there, make sure your plug and air filter are clean and then maybe worry about more full on procedures.
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Joined: Jan 2009
Posts: 6,926 Likes: 10
Pushrod Honda preferrer
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Good point Joe, some Hondas seem to have a propensity to clog their air filters rather quickly, and that will cause loss of power (as well as rich running and high fuel consumption). Also, if it is a GCV160 (160 cc Over-Head Camshaft) there is a chance it has slipped its rubber timing belt, which would cause a sudden severe loss of power. The specified compression pressure for the GCV160 is 71 psi, the same as the GXV120, so you still do not seem to have a problem in that area. This is Honda's troubleshooting chart for loss of power: ![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/01/full-2772-4802-honda_gcv160_diagnostic.jpg) Since your compression is OK, piston and valve seat problems are relatively unlikely - I suggest you check the other items listed first. Here is the abbreviated workshop manual for the GCV160: http://www.honda-engines-eu.com/en/images/992.pdf
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Joined: Apr 2011
Posts: 5
Novice
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Yeah sorry fellas,never got a chance to get back to it today but its the overhead valve job with the plastic cam and rubber timming belt ,thanks for the advise so far will get into tomorrow after i do a few hours cutting on the ride on
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Joined: Apr 2011
Posts: 5
Novice
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Joined: Apr 2011
Posts: 5
Novice
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Thanks fellas ,i finally got a chance to work on it the other day and yeap it seams to run heaps better after resetting the gov ,just got another Q ,what sort of RPMs should this thing be turning at with no load at full throttle?
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Joined: Jan 2009
Posts: 6,926 Likes: 10
Pushrod Honda preferrer
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The maximum HP speed for your engine is 3,600 RPM but Honda specifies that 3,000 RPM is the "rated speed", so that will be the highest speed your governor allows. There are safety, as well as engine life, issues in running an 18" rotary mower above 3,000 RPM. This is an industry standard and is based on blade tip speed. Direct drive rotary mowers with a larger cutting diameter will be rated at, and limited to, lower speeds than 3,000 RPM.
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Joined: Apr 2011
Posts: 5
Novice
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Thanks grumpy ,good to know,will throw the tach on her and see
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