G2/9 issue

[nitro1]

Making this post for all upcoming problems I’m finding with this cart I just bought.

The problem I hear is a knocking noise and I no there can be many things to be known but I decided to check the valves first they look pretty even and pretty firm with a very tiny play.

I had bought a new spark plug so once I took out my old one I decided to hit the gas pedal and weird no knocking noise ??? New plug in and the noise is back ? What is my issue

[CP241]

So with no spark plug there’s no knocking but with a spark plug it does knock?

When the spark plug is removed, there’s no compression and no combustion driving the piston back down. It’s unloaded kinda like “driving” with the back end up on jackstands. The wheels are spinning but there’s no real “load” on them.

Something is off inside the engine. My guess is rod knock but that’s just a guess. Video would help.

Or you could just give it to me. I’ll find a home for it

[nitro1]

Maybe when I get tired of repairs on it lol but yes no knock when spark plug is out and knocking when the plug is in

I’ll post a vid when I get a chance to make one

[nitro1]

BTW CP241 the amazon carb with the 120 jet u told me about works great did not have to make any adjustments

[nitro1]

Came across this vid and it sounds like mine

https://youtube.com/shorts/RQgCanTrzo4?feature=share

[CP241]

If yours sounds like that with a deep rotational knocking noise like that, in the Yamaha engine it’s definitely rod knock. Club car has a counterbalance weight that moves up and down like a piston and knocks but the Yamaha has a counterbalance shaft that spins.

I’d pull the engine out and pull it apart if nothing else, to double check everything. It only takes a split second to create a hole in the motor and then it’s no longer rebuildable.

[nitro1]

Here is my cart noise

https://youtube.com/shorts/Wg5NXNzLxV0?feature=share

https://youtube.com/shorts/lBu8VjKbz9s?feature=share

[CP241]

I was actually thinking it sounds like it’s in the clutch in the 2nd video but I’m the first one when you’re real close to the cylinder it’s very loud in the microphone there. I’d say it definitely sounds like it’s inside the engine, at least from my recliner here

It does sound kinda higher pitched than I would expect from a rod knock though. What’s it sound like when it actually runs?

Maybe wrist pin or the counterbalance shaft can tend to wear its journals in the case. I don’t know what that would “sound” like though.

If it were mine, I’d pull the engine and tear it down. See what’s really going on in there. Almost sounds like it might be in the head too but I’ve never heard valves sound like that… seems awfully high but it may just be the video

[nitro1]

When it actually runs it sounds like a steady knock, what would I need to order when I tear this down ?

[CP241]

Never know until you tear it down and see what’s wrong. There’s probably something worn that needs to be replaced. Maybe rod bearings maybe something else.

What kind of compression does it have?

I’d tear it down, and measure everything. I have the repair manual and can email it to you if you need it. Just pm me your email address.

Any parts you need to order plowmans probably has in stock for a quick delivery.