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Gas Yamaha Gas Yamaha Golf Cars; G1 through "The Drive" and U-Max Utility Vehicles |
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02-17-2012, 12:50 AM | #1 |
Not Yet Wild
Join Date: Jan 2012
Posts: 4
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Yamaha G1 with bad bearing, seal, and piston rings.
We've had this golf cart for years on a dusty horse ranch and finally drove it into the ground. When the cart finally stopped running the compression was 0 PSI and puffs of smoke could be seen escaping from behind the clutch when the engine was turned over. We took the engine off and broke it apart to see what we needed to replace and here's what we've found:
The clutch side seal was completely worn out. Upon removal of the clutch part of the seal fell off. When we removed the cylinder head and cylinder we found half of the top cylinder ring was actually missing and there were some small score marks on the side of the piston. When we pulled the case halves apart I was shocked to see the reason for the clutch side seal going out was the bearing was missing half the cage and the jagged edge had cut it up. My current plan is to replace the two main crank bearings, get an oversize piston and rings, have the cylinder machined (assuming it's not scored beyond repair, which it doesn't seem to be), replace the seals and gasket, put it back together and see what happens. Does this seem like the right thing to do? I'd love to get a complete rebuild kit and replace the crank and cylinder head at the same time, but we're short on money at the moment. Any ideas, suggestions and/or comments are greatly appreciated. :D |
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02-17-2012, 07:02 AM | #2 |
Searching for The Way
Join Date: Oct 2009
Location: Medina, Ohio (NEOHIO)
Posts: 11,441
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Sounds like you are on the right track. The only thing that will determine if you need a new crank is if you have a lot of lateral movement on that connecting rod. Move it from side to side and see if it has slop. I'm guessing it probably does. If so, you'll need a crank and rod kit. If it feels tight you can give it a try. But judging on the condition of the rest, you might just plan to put a crank in it.
The crank is actually two pieces, pressed together under the connecting rod. They come pressed together with a new bearing and connecting rod ready to go. I would not advice trying to pull the crankshaft apart to remove the rod unless you have access to the proper tooling required. Check the service manual for procedure on this. I found a crank kit for around $160 online. Good luck. |
02-17-2012, 09:53 AM | #3 |
Not Yet Wild
Join Date: Jan 2012
Posts: 4
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Thanks. I just went out to take a look at the crank. If I move the top of the rod back and forth like a lever there is about 1/16th of an inch of movement. There isn't a whole lot of back and forth movement where the con rod attaches to the crank, but there is movement. I can check the play with a shim gauge if there's some kind of tolerance for it.
As far as trying to pull the crank apart, if I need a new one any way, I'd probably try it just because I have nothing to lose. Is there a service manual online for this engine? |
02-17-2012, 11:26 AM | #4 |
Searching for The Way
Join Date: Oct 2009
Location: Medina, Ohio (NEOHIO)
Posts: 11,441
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
I had to buy a manual, it was like $50 but money well spent. Take your time and do it right, do it once. That's what my grandpa used to say lol
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02-17-2012, 11:58 AM | #5 |
Not Yet Wild
Join Date: Jan 2012
Posts: 4
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
hehe, I like the saying, "do it right or do it twice."
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02-17-2012, 03:23 PM | #6 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,445
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
You can cut the head some for a little more power, they are very low compression....while you have it apart. Make sure the muffler is not plugged.
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02-17-2012, 03:51 PM | #7 |
Not Yet Wild
Join Date: Jan 2012
Posts: 4
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Thanks, I look into cutting the head, how much can be removed and how much of a difference will it make? The cart has been rich and smoking for a few years. It took it a looong time to finally break down. The muffler at one point was shooting sparks (not good on a dry pasture). My guess is that it is clogged. Is BBQing it a good idea? My friend who owns the golf cart is pretty larry of that.
I took the torn apart engine to a local 2 stroke engine mechanic who was familiar with the g1 engine today. He told me the play on the con rod was well within reason and that he's put them back together with even worse play (There isn't much lateral movement). He also gave me some ideas for lifting the cart using 4-6 inches of square tube attached to the struts to lift them up. I think that's something we're going to do. I should post some images. |
02-17-2012, 04:07 PM | #8 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,445
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Usually the muffler gets full of 2 stroke oil over time and short trips, because it stays cold. So if you run it hard for a while it will burn in there and smoke a lot, then spark too. If you run it hard or longer time often it will keep muffler clean and not do this. Some carts get old and oil in there dries out and will not burn, those they put in fire (BBQ) to make it burn out. I used to hold cart on floor and drive around with no governor or clamp on the gov, when it started to smoke I would hold it on the floor and keep hitting the brakes to slow down once in a while. It would smoke a lot, I mean a lot like clouds that hid homes lol. After 10 min it would turn blue and stop. If dark then I'd see sparks and muffler was really hot. I would then take it easy and just drive around normal so it could cool off some. I did this at a GC once in a while the cart would run poorly and not climb hills, they would hold it out for me to service lol. I was a kid and it was lots of fun.
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02-22-2012, 01:14 PM | #9 | |
Getting Wild
Join Date: Feb 2012
Location: Ontario Canada
Posts: 106
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Quote:
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02-22-2012, 03:05 PM | #10 |
Getting Wild
Join Date: Sep 2011
Location: Fairfield Ohio
Posts: 81
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Re: Yamaha G1 with bad bearing, seal, and piston rings.
Mine is .075mm over on the cylinder an I had .030 taken off the head. I don't know how it ran before I got it because it was the same as yours but it runs real good now. I'm very happy with it.
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