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04-22-2016, 06:30 PM | #1 |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Yamaha G2 Compression
I recently brought a Yamaha G2 and it runs good but when I did the compression test. It showing between 85 - 90.
I haven't done the oil test yet to see if it the ring or valve but I am wondering after I do the oil test and it the rings, should I just rebuild the cylinder and ring only or do the whole rebuild? Whole kits seem to cost close to 300 bucks so I am not sure if it worth doing full rebuild or just piston/ring only or value only . Feedback? Thank you Bill |
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04-22-2016, 06:53 PM | #2 |
Over This Interview Is...
Join Date: Jun 2012
Location: AZ
Posts: 17,449
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Re: Yamaha G2 Compression
85-90 psi should run like total crap. I kinda suspect the gauge. Try it on something else.
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04-22-2016, 07:22 PM | #3 | |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
Quote:
This is my first gas golf cart so maybe I could be wrong about it running good. I don't have other gas golf cart to compare how it runs and being Deaf doesn't help either but I had a hearing person listen to it and he thought engine sound okay. I saw little black smoke coming out of exhaust but previous owner said that normal after being in storage for so long. Anyway ...... I squirted some oil in it and it jumped close to 120 psi so it mean worn rings or piston. And the valves are probably okay. (I hope) Spark plug (photo below) came out all black tipped which imply to me that oil got to it. Now ...... I probably could get away just replacing piston and ring since it still have compression at 90 psi mean I could still could purchase and stay with standard size piston and ring? Or should I go rebuild the whole thing? I am not sure if it worth spending 300+ dollars for the rebuild kits Feedback??? Thank you Bill |
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04-22-2016, 07:24 PM | #4 |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
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04-22-2016, 07:30 PM | #5 |
Sometime's............
Join Date: Oct 2007
Location: Tacoma Washington
Posts: 11,868
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Re: Yamaha G2 Compression
Did you do the test at "wide open throttle"? Do the throttle cables open the throttle shaft to "wide open throttle? Was the battery fully charged and cranking the engine over fast? Are the valves adjusted to spec and not stuck partially open? Do you see any oil/dirt around the cylinder cooling fins? Sorry, but these questions must be asked for correct compression testing.
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04-22-2016, 08:14 PM | #6 | |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
Quote:
Now the second gauge tested at 145 to 150 psi and when I squirt oil in it, it jumped to 160 psi What you think? worn rings still? Bill |
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04-22-2016, 08:20 PM | #7 | |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
Quote:
I have not checked the valves specs since I don't have a gasket replacement for the valves cover (I think it leaking around the cover anyway) but I did step on the gas petal all the way down. Battery is somewhat new. When I went to check the cart out, the first battery in it wasn't cranking the engine so the previous owner pulled out a battery from his truck and said he just brought it a month ago (it still shiny and no gas/oil/dirt on it) then I was able to test drive it. He let me have his battery when I brought it from him. But I haven't read up yet but I do notice there 2-3 second delay between pressing the petal down and the starter to start spinning. Sometime it wouldn't spin so I release the petal and press it again then it would start spinning again. Not sure if that normal or something need fixing/replacing. Anyhow I went and swapped out the gauge It reading at 145-150 psi and with oil it jump to 160 psi. Still bad rings? Bill |
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04-22-2016, 08:36 PM | #8 | |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
Quote:
I went back and removed the air filter tubing off the carb. Then did a test again using my hand to hold the throttle wide open. It still reading at 150 psi. I can't see the cylinder cooling fins very well (my flashlight batteries dead) but it have oil all over the engine which I think the valve cover is leaking oil. When I pulled the air filter off the carb, I notice oil in the air filter tubing as well and some oil inside the carb mouth so maybe black smoke is coming from the oil overflow going back into the carb? What you think? I have not drain the oil yet (which I should have done first thing) but I haven't run it much either just did a test drive and then drove it off the trailer into my garage afterward it sat there since then. Thank you for feedback Bill |
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04-22-2016, 08:41 PM | #9 |
Gone Wild
Join Date: Apr 2016
Location: Springfield, MO
Posts: 195
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Re: Yamaha G2 Compression
My service book said minimum is 142 psi and max is 199 psi.
Is it worth the trouble to get more psi out of it? More torque for hill climbing right? Bill |
04-22-2016, 08:58 PM | #10 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,433
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Re: Yamaha G2 Compression
Up to you, doubt it would change power output much. I think new they were 180 or 185, the G9 was little less, newer carts are less yet. I would say consider putting a clone in, you get twice the power and a new engine. Its some work installing it but once its done you will be impressed.
The oil ring goes first on these often, so they still run but burn oil. If they get a lot of blowby they will puke it into the airbox. However it should not oil the filter unless the oil was overfilled. You can never put more than 1 qt in these, you should change oil and put 1 qt in and check the stick on level ground, then never put more than what the stick shows with 1 qt. If you don't have too much oil and it is puking oil into the airbox, it likely has a lot of blowby. They will get a film of oil in there normally, but not oil in the bottom. You can ring them but like with anything it is a bandaid fix, while a new bore is like new. If it is weak on hills check the drive belt, it should be over 1" wide. They are 1 3/16 new and they run best with a newer one far as power. |
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