CVT qustions...rattle By Jon C (Read 8,560 times)

[Bashan]

Jon, there's a GY6 cutaway illustration under "tech and tutorials" that shows the gear mechanism for the starter, that might give you an idea of where you're listening. Rich

[Jon C]

I'll post more later, but here is my poor scooter:



Jon

[zugzug]

The last time I heard a engine knocking that bad was years ago on my methanol gocart about 30 secs before the rod came thru the block.
-Zug

Dont run it anymore. You dont want it to come loose and destroy the engine.

[Jon C]

Well, I was only hoping it was something easier. I was in denial. Looks like I'll be doing a rebuild.

[Alleyoop]

Well sure does NOT sound like a bad rod, rods have a KNOCK, KNOCK SOUND and as you give it gas the KNOCK also speeds up. The engine appears to run very smooth. It sounds more like thinney thing are you sure its not your muffler parts inside flying around. Its a constant noise thinney noise. Put the listen device on the Muffler and also on your header pipe and on the valve cover and also by your tranney.
Alleyoop
I would check something in your pipe or muffler first, there is something loose somewhere.

[Jon C]

Maybe there is hope? I'm glad the last post didn't think it was a rod.

Remember, I lost no power and was running fine. Also when I drained the oil, I didn't see any obvious metal shavings. That made me wonder?

In the video I posted earlier, I mostly pointed the camera at the magneto rotor (I think its called). Because to me that is where the most noise was. Others agreed, in fact it is right above the starter.

Here is a video of me hitting the starter with the cover or rotor off...listen for the knock, clatter, or marbles...I don't hear any:

[Jon C]

So, I took the rotor off and there are gouges where the key goes on the rotor. I'm thinking the key got loose and was causing the noise. What is that key called...woodruf, or something?

There was also a ton of dust in there from dirt roads. I can't get pictures now because my camera is having issues, but I will get some.

The key itself looks good, and same with the shaft.

The first thing I'm going to do is get this part:

www.motopartsmax.com/index.php/main_page/product_info/products_id/610

If anyone knows a good place to get this part, let me know. I'll look locally first.

If anyone thinks it is something else, I'd love to hear all opinions.

Jon

[Jon C]

One more thing I should note. I couldn't get the magneto cover off, so when I ran it for a buddy to listen to, the bolt was off and the cover came off on its own.

Now that I think of it, maybe that is why there are gouges in the slot came from?

[runningslow]

Sounds a little like my scooter... right before the motor seized on me. However, when I drained my oil, I found plenty of metal shavings. A magnet helped, but even when I dumped my drain pan into my recycle bottle, it kinda felt like I was panning for gold. Plenty of metal... and I still haven't found the source.

[Jon C]

Apr 19, 2010 10:28:13 GMT -6 runningslow said:

Sounds a little like my scooter... right before the motor seized on me. However, when I drained my oil, I found plenty of metal shavings. A magnet helped, but even when I dumped my drain pan into my recycle bottle, it kinda felt like I was panning for gold. Plenty of metal... and I still haven't found the source.

Yes, I've been following your thread.

I cleaned the magneto rotor and stator, and put it back together. Sounded better, but it is still making some noise mostly at idle. The slot where the woodruff key goes is too chewed up.

Just ordered a new one, so I'll have to wait a few days.

Thanks.

[Jon C]

*Solved*

The rattling noise I was hearing was from a loose magneto rotor. When I took it off, the groove where the Woodruff key goes was all chewed up on one end. I don't have pictures now, but I'll try to get one another time.

I replaced the magneto rotor and it sounds good now. I used lock-tight on it and tightened it good. Sometimes I still hear a rattle when it is at idle, but not much.

I'm not 100% sure yet if I trust it, but I'll post again if I have trouble.

I'm just glad it wasn't internal like I thought it was. That mechanics stethoscope did help me narrow down where the noise was coming from.

Thanks for all the posts in this thread!

Jon

[Bashan]

Great summation Jon, that's how we all learn. I'll file that in tech as a possible cause of engine rattle under a engine diagnosis tutorial we're working on. Thanks, Rich

[Jon C]

I may have spoken too soon...

I've been having trouble getting the right woodruff key. It sounded good for a while, but the rattle came back after a few miles. I ordered the right key from www.scrappydogscooters.com/ and it should get here soon....but....

I notice that when I move the crank shaft back and forth there is some play in there that makes that same rattle noise? Hmmm.

Is it possible that the cam chain is too loose? Should there be any play in the crank shaft?

I am going to try to adjust the cam chain tensioner and see if that play I have goes away.

I didn't want to start a new thread, so hopefully someone will see my last 2 questions. I may try to get a video up of what I'm talking about.

Thanks!

[Bashan]

I speak from having read the Haynes manual a few times, not practical experience other than I used to work on MC's a lot when I was younger. Yes it could be the cam chain, that's why they have the tensioner . If you don't have the procedure for tightening it let me know and I'll get the Haynes out, I am so sick of trying to l Google stuff lately I'm going crosseyed. Why do you say there's crank play, waht are you basing this on? There shouldn't be any from the top of the piston to the crankshaft, I would say that's universal to all internal combustion engines. Rich

[Jon C]

Thanks Bashan, now I don't think it is the cam chain. I tightened it, and nothing changed.

This play is hard to explain, but its like the connecting rod is loose or maybe just some gears that have some play.

Or is this play normal?

The video can explain more. The clanking noise is near the rear wheel. I only used part of the variator to move the shaft. (Yes, I did get a new variator if you notice the broken blades...Don't use a screw driver when removing the nut)!