Changing Valves

[Ktrilla]

I have a Yamaha G9 that likely needs an engine rebuild. Before I do that, I am thinking I’ll check out the Valves. Do I need a special tool for that engine or can I likely go to an Autozone to get a tool to compress the springs. Any advice or guidance would be appreciate. Thanks!

[cgtech]

The springs arent very strong, it's easy to press them down with pliers & remove the keepers.

[Ktrilla]

Thanks!

I am going to dig into the maintenance manual. But if you are willing to share your perspective, is it a pretty easy process to change out the valves? I have never done it...

For reference, the cart sat idle for years. I think it was rolled over based on the body damage. When I started working on it the engine was sputtering and no real power. I opened up the valve area and found that the valve was off the rocker. I was able to get that back on and now it runs great but smokes like crazy. Everyone says (and for good reason) it’s a piston ring. But given that the valve was screwed up, i want to rule out a simple fix before I try to change the piston rings.

[Jammy]

Originally Posted by Ktrilla

I opened up the valve area and found that the valve was off the rocker. I was able to get that back on and now it runs great but smokes like crazy.

I am not sure why it is smoking and you can do a compression test to assist in troubleshooting the problem Also a leak down test may help.

As for valves...try setting them to 0.004 on both intake and exhaust when on the TDC of compression stroke!

Good luck.

[cgtech]

Originally Posted by Jammy

I am not sure why it is smoking and you can do a compression test to assist in troubleshooting the problem Also a leak down test may help.

As for valves...try setting them to 0.004 on both intake and exhaust when on the TDC of compression stroke!

Good luck.

These G2/G9 carts are known for oil rings wearing out after 30+ years, but the compression rings are still ok, so it wont have a terrible compression test score, will drive with ok power, and smoke like crazy.

[cgtech]

Originally Posted by Ktrilla

Thanks!

I am going to dig into the maintenance manual. But if you are willing to share your perspective, is it a pretty easy process to change out the valves? I have never done it...

For reference, the cart sat idle for years. I think it was rolled over based on the body damage. When I started working on it the engine was sputtering and no real power. I opened up the valve area and found that the valve was off the rocker. I was able to get that back on and now it runs great but smokes like crazy. Everyone says (and for good reason) it’s a piston ring. But given that the valve was screwed up, i want to rule out a simple fix before I try to change the piston rings.

It's not too bad, but I personally wouldnt bother changing the valves, (maybe the intake valve stem seal, which is pretty easy, none used on exhaust). I've seen so many old ones with worn out rings, (I've owned 2 smokers myself & 5 total), I quit with the bandaids, and just kept oil in it until I got rid of it. These were free carts, with huge amounts of hours on them & poor condition bodies too, so I wasnt sinking money into them. I just gave them to friends & family to use however they chose, with the info of what could be done to them.

I've rebuilt some & have worked for a yamaha dealer for 13 yr.