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Gas Yamaha Gas Yamaha Golf Cars; G1 through "The Drive" and U-Max Utility Vehicles |
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11-22-2009, 08:56 PM | #1 |
Not Yet Wild
Join Date: Oct 2009
Posts: 18
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New G2 Project
I have started working on a second project - a 1989 G2 gas cart. I got the cart out of a barn where it had been sitting for about the last 6 years or more. The engine had no compression, so I put the piston at tdc and filled the cylinder with PB Blaster. It didn't drain down so I assumed the ring wasn't stuck. Next I pulled the valve cover and found a stuck valve. More PB Blaster and then I adjusted the rocker arm tight enough to make the valve move up and down when I turned the engine over by hand. I left it sit over night and then re-adjusted the valve. Re-checked compression and now its at 155 psi.
Changed the oil, put in some fresh gas and after some cranking got the engine to fire and start running. Now that its running, the primary clutch has a broken weight and split dust cover. So I take parts from the old clutch off the G8 (http://www.buggiesgonewild.com/gas-y...yamaha-g8.html) and this one to try to come up with a working clutch. I tried to get the whole clutch off, but didn't have any success getting the inner sheave off the crank. I'm open to suggestions as to how to do this. I re-installed the newly rebuilt primary and put the old belt on and took it for a spin around the barn yard. Surprisingly enough got 12 mph out of it. Since things seemed to be going well, I adjusted the governor spring all the way and increased the mph to 15. Now the not so good news. When its running, sometimes it will want to backfire and the rpm's don't want to come up. If I stop and back up, then go forward it seems to want to go a little better. I'm wondering if the primary may be binding causing the decreased rpm's. Also when the cart is in neutral and running, I can see the whole clutch moving slightly in and out away from crank case. Could this be early signs of a crank bearing failure? How much play if any is acceptable? If it is the crank bearings, how difficult are they to replace? Thanks in advance for your help. |
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11-23-2009, 03:05 PM | #2 |
Admin
Join Date: Dec 2006
Location: TN
Posts: 101,826
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Re: New G2 Project
Sounds like a good cart. Get us some pic's if you can. You may just be having a problem with the throttle adjustment. Backfiring usually is from the throttle on the carb not closing all the way when you let off the gas. You'll probably need a puller for the rear sheave if it seized. I've used a steering wheel puller on mine before and you can pick those up at any local auto parts store.
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11-23-2009, 04:27 PM | #3 |
Gone Wild
Join Date: Nov 2009
Location: Kentucky
Posts: 287
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Re: New G2 Project
it sounds like the crank bearing, similar to one of my g2's that had been sitting for more than a year. ended up now in the process of a complete rebuild. you'll need a sheave puller if its pressed on the shaft tight, i used a regular auto pulley puller i had laying around.
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11-23-2009, 09:33 PM | #4 |
Not Yet Wild
Join Date: Oct 2009
Posts: 18
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Re: New G2 Project
Thanks for the input. If it is the crank bearing, I hope it's the one on the clutch side. It looks like that would be the easier one to replace. I'm not sure I'd have the ability to change the one on the fan side.
I also see that there is a nut and lock washer on the fan side of the crank. Could it be possible that this nut needs to be tightened? The movement of the crankshaft is side to side about a 1/16". I need to get the inner sheave off first in order to try and see whats going on. |
11-25-2009, 07:14 AM | #5 |
Not Yet Wild
Join Date: Oct 2009
Posts: 18
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Re: New G2 Project
I took the time yesterday and pulled the engine out of the cart. Was finally able to get the inner sheave off. I drained the oil and took the crank case cover off. Sure enough the clutch side bearing is o.k. The fan side bearing is the one starting to go. Here is where I need help. I have never rebuilt a 4 cycle engine before. Can I remove the crank without taking the head off? I found marks on the camshaft gear that line up with the crank gear, but couldn't locate and marks on the counter balance gear. Am I correct in assuming that the counter balance needs to be in time with the rest of the motor. I am also concerned about the connecting rod bearings since the crank was moving back and forth.
If anyone has any pics or info on how I can do this, I would greatly appreciate the help. Thanks |
11-26-2009, 01:36 PM | #6 | |
Kid no more!!
Join Date: Feb 2007
Location: Bradford, Ontario, Canada
Posts: 750
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Re: New G2 Project
Quote:
I took a look through my stash of pics and this should help expain how to line them up. On the crank you will only see one indicating mark, that one you line up with the mark on the cam gear. Now the balancer shaft, has a mark on it as well. With the 2 other marks lined up, line up the balancer shaft so that the mark is pointing towards the middle of the crank. Some of the yamaha cranks just didnt have 2 indicating marks on the crank gear.. well the ones that ive seen.. Supposively in the rebuild manual these 2 marked cranks existed. lol Dont forget to prelube the crank bearings and such when you put the engine back together, this will help pervent a dry start and seize the motor. |
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11-26-2009, 02:28 PM | #7 | |
Admin
Join Date: Dec 2006
Location: TN
Posts: 101,826
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Re: New G2 Project
Quote:
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11-26-2009, 02:32 PM | #8 |
Kid no more!!
Join Date: Feb 2007
Location: Bradford, Ontario, Canada
Posts: 750
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Re: New G2 Project
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11-26-2009, 02:40 PM | #9 |
Admin
Join Date: Dec 2006
Location: TN
Posts: 101,826
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Re: New G2 Project
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11-26-2009, 03:00 PM | #10 |
Not Yet Wild
Join Date: Oct 2009
Posts: 18
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Re: New G2 Project
Thanks for the pic and the explanation Monster. Do I have to pull the head before I remove the cam shaft or can I just adjust the valves loose enough to remove the push rods?
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