Clunk when turning engine off

[xjwmx]

I started a thread on this a while back but without a video. Sometimes it will clunk when I turn the engine off and sometimes there's no sound, and other times a kind of a whirr as it turns off. I'm concerned about the clunk but I'm at a loss as to what it could be.

The first example of the clunk sound is at about 1:13. Sometimes it is louder than this, like a bang. Any ideas?

https://drive.google.com/open?id=1P64dMi-qJSnEo4f_knviHNfj0i94dq7Y

 

[Superjet]

I had earphones on and sounds like the starter gear still engaging off and on. Maybe someone else can hear what I am hearing.

 

[TwoManyXS1Bs]

I hear a rapid rattle/clatter on shutdown.
Like steel clattering on aluminum.
Or a handful of ball bearings dropped down a pipe.
Which would be like a bearing that lost its cage.

First quickie test I'd do is:
Remove plugs, points and rotor covers.
Starting at TDC, rotate crank fore/aft and look for pause/delay in camshaft rotation.
Also, listen for tap sounds.
If so, suspect front guide, maybe debonded guide rubber.

On shutdown, spinning things have to stop.
The spinning crank stops, and the camshaft and clutch have to follow suit.

To eliminate half of the clutch, and mainshaft, do it again with the clutch pulled, tranny in any gear. Note any difference. If different, suspect clutch and such. If not, we're back to the front half of the engine.

Another test is to listen for sounds during engine rev-up and rev-down.

Probably best to use mechanics stethoscope during shutdown. Probing the front guide bolts, and the case at the outer cylinder bases (main bearings). Then probe around the rear tensioner. Lastly, the cam bearings...

 

[gggGary]

I'd suspect slight backwards engine rotation from compression with normal sounds of cam chain slack reversal maybe kick start acting is a positive stop? Remember these WON'T roll backward clutch in, in gear.

 

[JRay77]

I'm gonna guess starter and gear engaging assembly. Drain the oil, take the starter out, and plug the hole. Fill it back up with oil and see what happens. When you drain the oil, if you see plastic, excessive metal/shavings that'll help narrow it down. Maybe even check the sump filter for shit. My intentions are never to insult anyone's intelligence. With that said, when I buy a motorcycle, I consider maintenance that'll need to be done. I like to keep gasket sets on hand to prevent downtime. Filters and whatnot too.

 

[Tomterrific]

The starter button grounds the selenoid for the starter motor. If the wire from the start button has the insulation worn to the point it contacts the frame, probably at the steering head, the starter motor will start spinning. Why do I know this? It happened to me on a ride. Found, fixed.

Tom

 

[xjwmx]

First quickie test I'd do is:
Remove plugs, points and rotor covers.
Starting at TDC, rotate crank fore/aft and look for pause/delay in camshaft rotation.
Also, listen for tap sounds.
If so, suspect front guide, maybe debonded guide rubber.

Did this and observed some interesting things. First I turned it CCW and there was a distinct and regular ratcheting sound. Turned it CW and it felt like it was being blocked, and sounded slightly familiar, if you follow...a little like the clunk. Turned it CCW some more, more ratcheting, Then CW and it now turned freely. Then CCW and no more ratcheting sound. At this point all normal both CCW and CW. Front guide is only a couple years old, but I ordered it from...that place. When it was making the ratcheting sound it was harder to turn, like there was a little bit of drag on it like maybe starter motor or some of that gear train. Hope to get it ratcheting again and be more thorough. Was kind of in shock.

Also, the clunk sound happens both in neutral and in gear with clutch pulled.

 

[TwoManyXS1Bs]

Well, that's not good.

I guess the next step is pull the right cover, pull the starter bendix, do the same test.

Was there any camshaft hesitancy during this?

 

[JRay77]

• I've gotten rid of starters and just went kick only. I'm not a starter hater but they do draw a lot of amps. They're heavy. The original wiring to these (if you have it) gets old, brittle and can be hazardous. I just suggest if a person is physically capable, get rid of the sumbitch. Haha!

 

[xjwmx]

Haven't been able to get it back into ratchet sound mode yet doing anything I can do w/o oil in the bike. Need to be able to do this to track down problem more easily when bike is apart. Have another trick up my sleeve. Might have to wait for mosquito coils to come in. Can't find them locally. Going to see if a Swisher Sweet will do the job. Hoping to find snap ring gone off end of started gear boss. Possibility.

I'd suspect slight backwards engine rotation from compression with normal sounds of cam chain slack reversal maybe kick start acting is a positive stop? Remember these WON'T roll backward clutch in, in gear.

That was my first thought, before the ratcheting business. Now am hoping some gear under right cover is loose.
Yours won't roll backward, clutch in, in gear? By clutch in do you me lever not pulled? Clutch should decouple everything.

 

[xjwmx]

You guys have good ears and good intuition. I think the problem is a folded up #2 spring. If it's not THE problem, it's a problem. Just seeing it from the outside so far. Pics to follow, especially if it's as impressive looking as it looks now.



P.S. Yep. The spring was wrapped around the sliding gear and there was actually about an inch of it under the wishbone I had to pull out with pliers. That intermittent ratcheting sound was the sliding gear engaging the flywheel, depending on what the cockeyed spring was doing. The gear would sometmes get cocked and keep the crankshaft from turning backward, which was the clunk. OEM spring seems to be available new for $10. Fortunately nothing looks ground up. So I will replace the spring and hopefully call it fixed. BTW, when you turn the engine off the crank does turn backward one rotation or so.