Author Topic: Noise from valve springs CB550k1 (Read 2312 times)

saxamaphone · « **on:** June 13, 2015, 10:41:50 AM »

Hi guys, I'm finishing putting my 550k1 engine back to gather after putting on new rings, honing the cylinders and lapping valves. The engine is in the frame but I haven't started it yet. I had missed the slot in the lower case for the cam chain tensioner so I had to take things apart and put it back together again.

When turning the crank there's a noise coming from the valve springs and I can see the valves pop up at the same time. I had thought the sound was because of the miscued cam chain tensioner but now that that's fixed it's still there. There was no sign of valve and piston contact when I had the head off to move the tensioner.
It only happens with the cam cover installed.

I'm certain the valve/cam timing is correct as per the manual, installed the cam cover with rubber bands, and I've adjusted the valves correctly as well. I still have the cam chain tensioner backed off.

Any ideas on what this is? Overlapped valves?

Here's two examples of the sound. It seems to be happening with all the valves. It's just before the valve starts coming back up. In the first video it happens at 12 sec.

It happens at 7 sec in this one.

toolguy · « **Reply #1 on:** June 13, 2015, 11:59:04 AM »

This is all a wild ass guess but. .
is the noise right when the piston is at TDC and closest to the valve??. . Back off the adjustment for the rocker you are listening to which will decrease the piston to valve timing. . . .if the noise goes away, you probably have piston valve interference.. Might want to recheck the cam timing. . with 1-4 at TDC are you sure the notch was at the 3 o'clock position? {Can also be on the 9 o'clock position with #4 at TDC}

Other thing to try, Can you feel the valve pop up when you here the click, or do you just hear the noise?
If it pops up the valve shaft is binding for some reason in the guide. . If you hear it and just feel a slight 'bump' I'd guess the valve is hitting the pistons. Still the same avenue to investigate, pull the cam cover and check cam timing

Just a guess but, what could be happening is the piston comes up, touches the valve that is still open because of incorrect timing and binds the valve stem sideways in the guide. . then as you continue to turn the crank and the piston starts to travel downward, it releases the binding and the valve pops up the rest of the way. . if this is the case, you'll want to check that the valves didn't bend. .

saxamaphone · « **Reply #2 on:** June 14, 2015, 12:16:15 AM »

Hey toolguy, thanks for your reply. I didn't try backing off the rocker yet but I was thinking that the valves were making contact with the pistons as well. I just took the cam cover off and the timing's right though. I had the tensioner installed incorrectly and I thought that was the problem but I fixed that and the sound is still there. I don't get it.

(This is at 1 & 4 mark but couldn't catch the 1 & 4 in the photo.)

IMG_2063 by HereIJam, on Flickr

IMG_2067 by HereIJam, on Flickr

saxamaphone · « **Reply #3 on:** June 14, 2015, 10:02:57 AM »

Hi, forgot to mention that the valves do pop up so maybe they are binding in the guides like you said. I'm not sure how to confirm that but I have another head that I might put on there to see if it does the same thing.

Don R · « **Reply #4 on:** June 14, 2015, 03:51:13 PM »

Could there be lapping compound in the guides?

saxamaphone · « **Reply #5 on:** July 15, 2015, 08:43:56 PM »

Hi, I cleaned the guides out pretty well and oiled them before putting it all together.

I have a spare engine so I thought I'd try some experiments. I tried a spare head cover with the original head (tappets adjusted) and the boings from the springs still continued. So then I tried a spare head with valves etc with the original head cover (timed and adjusted valves, adjusted tensioner) and still the same sound! As each valve goes down it pops before coming up.

I'm at a bit of a loss. I know the valve timing is right and I've adjusted the tappets correctly.

pangloss · « **Reply #6 on:** July 16, 2015, 01:05:35 PM »

From the above two photos, I'd say the cam is one tooth too far clockwise...

saxamaphone · « **Reply #7 on:** July 16, 2015, 08:31:08 PM »

Hi, I tried shifting the cam chain one then two teeth each way and no change in the popping sound when rotating the crank. I was hoping that was it but doesn't seem like it.

One thing I noticed when switching the heads is that I can't get slack in the bottom of the cam chain by letting it drop down a bit. I thought I should be able to move the chain around by lowering off the crank but I can't get any links to drop down on either side of the crank sprocket. Not sure if that's normal.

I took apart the original head and and I can't see any evidence of valves hitting the pistons. I rolled them all on glass and I couldn't see any warp. The one different thing is that the #1 intake valve was difficult to remove from the guide near the top of the stem. That wasn't the case before assembly.

Also when I push the valves down a bit without the springs installed they stick in the (new) valve seals a little bit but I'm not sure if they'd go that far down when the keepers and springs are there.

I'm still stumped.

saxamaphone · « **Reply #8 on:** July 17, 2015, 12:12:51 PM »

Could a stretched cam chain make it so the valve timing will never be right?

saxamaphone · « **Reply #9 on:** July 19, 2015, 09:59:43 AM »

Could a too thin base gasket make so there's not enough valve to piston clearance? I'm reaching here...

saxamaphone · « **Reply #10 on:** July 19, 2015, 12:21:39 PM »

I was watching through the spark plug holes with a flash light as I rotated the crank and found that valves seem to be coming up well before they would hit a piston, but they don't pop every time they go down and up. So it's probably not guides.
When they pop it is when the piston is coming up but the valve seems to come up in time so they don't hit the pistons.

Could the cam chain getting stuck on something cause something like this? The chain gets stuck on something then delays the valves coming up, and when the chain frees up the valves pop up.

I've been checking and rechecking valve timing and also trying it a tooth on either side but no changes.

jonda500 · « **Reply #11 on:** July 19, 2015, 05:54:29 PM »

unlikely I know, but it seems that both your heads have sticking valves? - the valve stems should slide easily in and out of the valve guides

saxamaphone · « **Reply #12 on:** July 20, 2015, 04:30:26 PM »

Hey guys, I was able to film through the spark plug and get a decent video of what's happening. When the valve pops back the piston is already well down the cylinder. The valve seems to sit there by itself and then pop back as the crank turns. You can see it pop back at 27 secs. Each valve does this. Seems more like springs or something to me now. Is there a way a problem with the cam chain could cause this?

There is only one right way to have the camshaft installed isn't there (i.e. mickey mouse ears on right side)? The manual and all the photos I've seen have the notch on the right side, same as they points.

saxamaphone · « **Reply #13 on:** July 21, 2015, 04:27:30 PM »

So I've take everything off down to the crank cases and haven't found anything out of place yet. Is it normal not to be able to move the cam chain around under the crank shaft sprocket even when you have tons of slack?

The valves popping back is definitely happening even when the pistons are nowhere near the valve. With out the cam cover on the crank turns easily and so probably not a problem with the crank or pistons but I was checking anyway today.

w1sa · « **Reply #14 on:** July 21, 2015, 05:52:33 PM »

If the clicking is being caused by a valve(s) binding in the guide(s).....you should be able to detect a momentary gap between the top of the rocker arm and the cam lobe , as the cam lobe actuates it,....... it may be the rocker is being left in an actuated position with the valve....followed by a sudden snap back or catch up of the valve/rocker (to the cam lobe) which presumably, could be causing the click, as the rocker slams back onto the cam lobe.....

Check for this while you have the cover off....

saxamaphone · « **Reply #15 on:** July 22, 2015, 09:01:06 PM »

Thanks w1sa, the rockers are all nice and loose when I have the cover off. The valves pop back even when I have the tappet adjusters backed off a fair bit.

lrutt · « **Reply #16 on:** July 23, 2015, 11:14:27 AM »

No coil bind is there? Don't recall on the 550 but they are symmetrical springs, right? is there an up or down. Are they double springs or single? Keepers and retainers all well seated? Cam chain is tight? is it new? no slop in the chain allowing the cam to snap a little when you get across a lob center or something? Just tossin ideas.

saxamaphone · « **Reply #17 on:** July 23, 2015, 12:12:06 PM »

Hey lrutt, I think they are symmetrical springs. I couldn't see a difference between an up and down. There are two springs: small interior and larger exterior, washers under both. Keepers and retainers are all well seated.

The cam chain isn't new and that's where I'm checking next. I have a new honda chain ready to put on. What you say about the cam snapping when getting across a lobe center totally makes sense.

I'll replace the chain tomorrow and see if it makes a difference.

Thanks.

saxamaphone · « **Reply #18 on:** July 31, 2015, 08:59:55 AM »

Hi, I just broke my cam chain to put on a new one and I'm not able to pull the cam chain out from under the crank sprocket. Is turning the crank the only way to move the cam chain? I thought you could drop it below the crank sprocket and pull it out.

saxamaphone · « **Reply #19 on:** August 04, 2015, 11:48:40 PM »

Replaced the cam chain with a new honda chain, put everything back together and getting the same problem. Tensioner and guide are in the right spot, cam timing is spot on, I always back tappets off and use rubber bands for cam cover.
How does one check for coil bind?

I can hear the tiniest of scraping sounds when I turn the crank really slowly and have my ear by the valves. Again it makes me think valves are hitting pistons but the cam notch is perfectly lined up at T 1/4. Plus looking in spark plug holes with a flashlight shows that it doesn't look like valves are hitting pistons. I'm not sure where to look now.

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Author Topic: Noise from valve springs CB550k1 (Read 2312 times)