Author Topic: 82 CB650SC Tappet Screw Missing (Read 1399 times)

janich4644 · « **on:** May 24, 2019, 11:29:21 AM »

Took my 82 650SC out for a quick ride yesterday and heard a lot of tapping coming from the top end. I figured it was the valves not being adjusted to spec. I took the covers off and noticed on the inlet of cylinder 2 the tappet screw and nut were missing. Took the cylinder head cover off and found the nut, but no tappet. felt around in all the crevices with a telescopic magnet but no luck. The only place it looks like it could have gone is down the cam chain void.

My question is if I'm to assume it went down the void, what's in the bottom of the void? How do I get to it? Does it just run down to the sump?

Bodi · « **Reply #1 on:** May 24, 2019, 01:14:09 PM »

if it didn't fall into the sump, I think you would have heard a lot of unpleasant noise and have some severe damage to deal with. It could easily fall into the cam chain - and going through the crank sprocket would not be pretty, the primary chain would be worse but it's less accessible to something dropping from above.
I had this happen on a CB77, the tappet and nut were in the sump undamaged. Taught me to torque those nuts down well.

janich4644 · « **Reply #2 on:** May 25, 2019, 06:01:14 AM »

I'm really REALLY hoping that that's the case. I didn't hear any unpleasant noises or anything I felt alarmed by so I'm hoping for the best.

flatlander · « **Reply #3 on:** May 25, 2019, 06:34:43 AM »

remove the oil pan and if you're lucky you'll find it in there.

BenelliSEI · « **Reply #4 on:** May 25, 2019, 03:22:01 PM »

If you don’t find it, install a drain plug with a decent size super magnet built in. I put them on all my bikes and recently found a very worn tappet nut. Weirdly, I instantly checked above, and they were all there. Can only assume it had been there a while.......

janich4644 · « **Reply #5 on:** May 25, 2019, 03:35:38 PM »

I haven't even heard of that! Will look into picking one up.

Hearing that it's most likely in the oil pan makes me feel easier about the whole situation. I'll probably have time to dig into it on Monday.

BenelliSEI · « **Reply #6 on:** May 26, 2019, 07:21:06 AM »

Definitely pull the pan and look for it! Not something you want floating around...... you can buy drain plugs with magnetic ends, I just buy a small stack of barrel shaped “super magnets” on line. Drill the same size hole in the drain bolt and drop it in. Drip some red Loctite in first, just to be sure, but they are so strong they are almost impossible to get out!

janich4644 · « **Reply #7 on:** May 27, 2019, 02:00:15 PM »

Bad news. Did not find the screw inside the oil pan today. Anyone have any next steps?
Good news, I did not find anything else in my oil pan besides oil

robvangulik · « **Reply #8 on:** May 27, 2019, 02:35:42 PM »

Hold your phone (or a camera) inside the crankcase and take some pics of the places under the crank you can't see from the outside.

janich4644 · « **Reply #9 on:** May 27, 2019, 02:44:09 PM »

Quote from: robvangulik on May 27, 2019, 02:35:42 PM

Hold your phone (or a camera) inside the crankcase and take some pics of the places under the crank you can't see from the outside.

That's a great idea. I'll take some pics and upload them when I can.

janich4644 · « **Reply #10 on:** May 28, 2019, 08:29:39 AM »

After letting all of the oil drop out over night after removing the pan, I was able to stick my head under there. Had some good flashlights, but I'm still unable to see any sign of the screw. Are there any panels on the side of the engine casing that I can remove to get a better view?

There is a potential that it went out with my last oil change this Spring. If that's the case I'll probably drive myself mad looking for it.

flatlander · « **Reply #11 on:** May 28, 2019, 09:12:18 AM »

did you look everywhere, really everywhere, in the cavity around the valve/spring? it could also be hiding in there.
i wouldn't risk running the engine with a loose item in there but since you changed the oil before finding it, i don't think you can do much more than search really thoroughly and then pray that it's no longer there.

janich4644 · « **Reply #12 on:** May 28, 2019, 09:31:01 AM »

Yeah, I checked in all of the cavities around the spring as well as the cavities around the cam with a magnet. There's also no weird resistance when manually turning the engine.

DaveBarbier · « **Reply #13 on:** May 28, 2019, 09:54:18 AM »

This might help. This is my ‘82 650 and as you can see there are plenty of places for something to get stuck in. Both are shots of the lower case.

DaveBarbier · « **Reply #14 on:** May 29, 2019, 03:17:21 AM »

I for one, think a tappet screw would be noticed coming out in an oil change. And it would have to be in the right orientation to come out with the flow of oil. I’m going out on a limb saying it’s still in there.

janich4644 · « **Reply #15 on:** May 29, 2019, 04:33:37 AM »

Thanks for the pics Dave. And yeah I agree. I think I would have seen it if it had come out. I'll be spending a few days fishing for it with magnets and see what happens. I have no experience taking an engine out or breaking one down so I'm really hoping I'm able to find it.

DaveBarbier · « **Reply #16 on:** May 29, 2019, 04:37:22 AM »

Endoscopes are pretty cheap nowadays. I have one that uses my phone as a display. It has magnet attachments and hook attachments and a light. I bet one would work pretty well for this.

janich4644 · « **Reply #17 on:** May 29, 2019, 04:58:29 AM »

I didn't realize they were so cheap now. I'll definitely be picking one up.

russ · « **Reply #18 on:** May 29, 2019, 05:53:45 AM »

mine fell out after cycle x did the motor, ken helped me in saying the valve cover can be removed without removing the motor on my 750 and with kens help i found it resting inside the head yaaaa.

janich4644 · « **Reply #19 on:** May 29, 2019, 05:57:22 AM »

Quote from: russ on May 29, 2019, 05:53:45 AM

mine fell out after cycle x did the motor, ken helped me in saying the valve cover can be removed without removing the motor on my 750 and with kens help i found it resting inside the head yaaaa.

Luckily the valve cover can be removed with the engine still in place in the 650SC too. I was really surprised that the tappet wasn't resting in there. At least the nut was sitting in there.

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Author Topic: 82 CB650SC Tappet Screw Missing (Read 1399 times)