Author Topic: Loud clicking from top end - not just a loose valve! (Read 8100 times)

Franky · « **on:** June 22, 2012, 12:47:41 AM »

Hi guys

This is the sequel to this topic: http://forums.sohc4.net/index.php?topic=102641

After the above, I had a machine shop and a guy with a good reputation give it an overhaul.
He did the valve seats/valves, put in new valve seals, replaced an inlet valve (cylinder 1) and an outlet valve (cylinder 4) - all genuine Honda. He also made the surface nice and even.

Well, I finally put everything together - very carefully - using the Honda, Clymer and Haynes manuals! Everything went fine and the bike started right up on the first kick. As I mentioned in the old post, it actually ran well before the teardown and after this forst start-up it seemed to run just as fine.

BUT!! There is a very pronounced, metallic clicking sound coming from the top. Using a screwdriver against my ear, I was able to pin it down to the intake valve on cylinder 1. The sound increases with revs and is definitely more clicking than rattling.

- I checked and doublechecked the valve clearance, and I'm sure I got the 0,05 and 0,08 right.
- I adjusted the camchain in several different ways (including the right way), but the clicking stayed excactly the same.

I then had a look on some photos I took during the process, and it looks like the machine shop shaved off quite a lot of material when evening out the surface:

Top before:

Top before close-up:

Top after:

Top after close-up:

Could this be the cause of the clicking? That the valve is kissing the piston? I think the new inlet valve appear to be sitting slightly higher than the others + it seems a little... beefier! than the others - this would explain that it is only this valve that does the clicking. Could it be because I didn't get the cam chain quite right? Any other ideas?

dave500 · « **Reply #1 on:** June 22, 2012, 02:15:17 AM »

gday franky,thats a lot of the head,,was it needed?,the valves with a stock cam are miles away from the pistons,,i dont think even with a lot removed from the head surface the valves are hitting the pistons,,with the head "shaved" or "planed" or "milled"itll sit lower and you might not be able to tighten the cam chain enough?with all the plugs removed and the engine hot and that tappet cover removed,rotate the engine over and again with the kick start by hand,,at the same time have a finger on the tappet,,try and feel if the valve hits the piston,you might feel a thud compared to the others?,also,,rotate that cylinder and watch the valves open and close,stop the engine at the point where both the inlet and exhaust are both open at the same amount,,now try and open the inlet further,itll be hard but you might be able to rig up a lever of a sort,,the valves are at their closest to the piston in this position,if you can push the valve down it clears ok,,you have great pressure of the dual springs to over come though,,engines are dummy assembled with very soft springs for this purpose,you have the standard flat topped pistons?

trueblue · « **Reply #2 on:** June 22, 2012, 04:33:57 AM »

The new valve probably has a thicker head because it hasn't been ground as much as the old ones, but if your cam timing is off it would cause this one valve to be closer to the piston by a fairy fart, and possibly touch.

Untold · « **Reply #3 on:** June 22, 2012, 06:17:57 AM »

I'm a noob when it comes to these engines, so I may be way off base. But I'm fairly proficient with 2-strokes, not sure if this would be different on a 4 stroke. That said, it looks like you lost your squish band. If I did this to one of my old mopeds, I'd have super high compression and possible "pinging". If it's not the piston actually hitting something, check out that option.

MRieck · « **Reply #4 on:** June 22, 2012, 06:51:39 AM »

You may have bent the valve stem when you put the cam cover on. Also....what the hell was running around in #4??

Don R · « **Reply #5 on:** June 22, 2012, 07:27:30 AM »

Milling the head will move the cam chain slack to the side with the tensioner and change the cam timing. Just one more thing to worry about if you didn't degree the cam. Maybe a compression test or leak down if you have access to a gauge set. A broken spring will click, look closely at them. I was shocked at the amount of material removed from the head. wow.

Old Scrambler · « **Reply #6 on:** June 22, 2012, 07:38:46 AM »

WOW! Thats some mill job! Check the inside of the inspection cap......I installed a double gasket to get rid of the 'tap' caused by the top of the adjuster hitting the cap.

iron_worker · « **Reply #7 on:** June 22, 2012, 07:52:13 AM »

Very good point about the cam chain slack being changed due to the milling of the head. Since the upper cam chain sprocket is attached to the head you've effectively changed the distance between the two sprockets. This would give more slack on the chain and could effectively change cam timing. Not sure if it would advance or retard... (I'm thinkin advance ... which could put your intake valve into a piston)

IW

crazypj · « **Reply #8 on:** June 22, 2012, 08:01:30 AM »

Quote from: MRieck on June 22, 2012, 06:51:39 AM

You may have bent the valve stem when you put the cam cover on. Also....what the hell was running around in #4??

That would be my guess as well, valve is sticking in guide
is it 500/550/650 head?
Pretty common for rocker arm to catch on valve tip and bend end of valve
you'll have to mill at least 0.020" to make any real difference to cam timing, but that looks like at least 0.020"and maybe 0.030+ has been removed?
Cam timing gets retarded not advanced, tensioner can cope no problem as long as chain and blades are in good condition (been there, fixed that)
There is also a possibility that piston is touching head, the combustion chamber looks like it got smaller.
You did check clearances before fitting motor?

phil71 · « **Reply #9 on:** June 22, 2012, 09:44:00 AM »

Maybe that machinist makes a nice living selling scrap aluminum on the side.

Franky · « **Reply #10 on:** June 22, 2012, 10:22:19 AM »

Damnit! For once I figured I'd take it to an experienced guy in a proper shop instead of tinkering with it myself... crap...

I'll look into the different pieces of advice and report back with my findings.

Here's a few answers for you:
- crazypj: standard 550 head. Everything is standard 550.
- MRieck: I think the PO had a valve snap which made the interesting pattern

crazypj · « **Reply #11 on:** June 22, 2012, 05:13:35 PM »

It's fixable, use a thicker solid copper head gasket, Lani can make them from 0/016" all the way to 1/8" thick, just tell him what you need
http://www.coppergaskets.us/
It would be a good idea to do the same mod as ffjmoore
http://forums.sohc4.net/index.php?topic=85698.msg1219934#msg1219934

dave500 · « **Reply #12 on:** June 22, 2012, 09:08:34 PM »

the stock pistons run flush with the deck,they wont be fouling the chamber no matter how machined it is,i had to have chambers milled out to clear domed xl125 pistons in a 500 though,,they were only a shadows thickness away from it.,,after youve tried to feel if the valve is hitting pull the head if you think it is,and you should see tell tale marks?,go back to your machinist and complain,,hope youve got 100 octane pump fuel over there?

you didnt fit a piston back to front so the relief eyebrow is too small for the inlet valve?

phil71 · « **Reply #13 on:** June 23, 2012, 09:38:01 AM »

I don't know what could have happened to that #4 that taking an 1/8" of material wouldn't straighten out.

maybe get this for safetey's sake
http://www.ebay.com/itm/HONDA-CB550-550-74-HEAD-CYLINDER-/150680228800?pt=Motorcycles_Parts_Accessories&hash=item23153dd3c0&vxp=mtr#ht_500wt_924

Franky · « **Reply #14 on:** June 24, 2012, 01:05:39 AM »

THANK YOU for your help guys. (and for the heads up on that top on ebay)

Well, the bike's sitting at the workshop of my Moped/MC club, so I haven't been able to check on things yet. I'll get out there tomorrow I think.However, here's a bit of news/answers/questions:

Regarding the cam chain timing: I did notice, that when aligning the mark on the cam, the 'T-mark' was a little off. (see image from workbook) Does this support the theory about that the timing has been altered by the excessive milling? Also, would a offset timing not effect the other valves too? And make it run worse/differently. It does run great - just with the clicking from #1.

Quote

I don't know what could have happened to that #4 that taking an 1/8" of material wouldn't straighten out.

The bike ran fine and did not leak (from #4) all last season with the funky #4 pattern, so I don't think there was a need to take away lots of material.

Quote

You did check clearances before fitting motor?

No, I guess that would've been a good idea. I just figured things would be fine since it ran so good before.

Quote

go back to your machinist and complain,,hope youve got 100 octane pump fuel over there?

I'll talk to the guy this week... interesting. We've got 98 octane here in DK.

Quote

You may have bent the valve stem when you put the cam cover on.

Is it really that easy to bend these guys? I was quite careful when putting it on. No hammers or anything. Also I made sure that no rocker arms were stuck when bolting it down.

Quote

you didnt fit a piston back to front so the relief eyebrow is too small for the inlet valve?

I didn't mess with the pistons at all. I did check the direction though and rechecked via some photos i took - the pistons have been correctly installed.

dave500 · « **Reply #15 on:** June 24, 2012, 01:12:50 AM »

it hasnt got an elongated rocker shaft hole in the cover?letting the rocker tip touch the cap?the new valve might be sitting lower in its seat letting the back of the tappet screw touch the cap?

trueblue · « **Reply #16 on:** June 24, 2012, 01:18:20 AM »

My theory on this one, your head has been milled too much, and this is causing the new inlet valve, which is ever so slightly longer than the rest of them to just lightly touch the piston and give you the click noise. Hence the reason it is only on number 1. But this is just a theory.

Franky · « **Reply #17 on:** June 24, 2012, 09:58:55 AM »

So I couldn't take it anymore and went to the shop and eventually pulled the head.

And sure enough... the valve had been touching the piston. There were slight markings on both the valve and piston of #1 and to a lesser extent on #4. I'll post some images when I get back home.

Now, I need some advice on how to increase the distance between the pistons and valves:

1. Add another gasket between cases and cylinder block. So two gaskets in total.
2. Find or make a one new gasket from thicker 'gasket material'.
3. Make a new copper gasket. I have access to a 1,25 mm sheet.

What should I do, oh masters?

crazypj · « **Reply #18 on:** June 24, 2012, 10:06:08 AM »

I would do copper gasket

Franky · « **Reply #19 on:** June 24, 2012, 10:42:59 AM »

Or could I just dremel a little of the piston? It seems to need so little...

dave500 · « **Reply #20 on:** June 24, 2012, 12:20:04 PM »

id complain to your machinist!

Franky · « **Reply #21 on:** June 24, 2012, 12:50:02 PM »

Here are some pics... Man, I guess I'm lucky the valves didn't get completely trashed!

Piston #1

Inlet valve #1

Inlet valve #4

This is the angle the cam is sitting at when the T-mark is in alignment... Is this caused by the missing material?
Dispite this, it seem to run great.

By the way: Does the tensioner look allright?

And yes Dave, I will complain. But, I 'm also keen on riding the thing soon

crazyPJ: One only uses the copper gasket, right? No ordinary gasket as well... Or is both OK too?

dave500 · « **Reply #22 on:** June 24, 2012, 12:56:36 PM »

the tensioner blade is cracking and might shed crumbled pieces id replace it,try moving the cam back one tooth and see how it lines up,id get your machinist to for FREE to mill all the pistons eyebrows to clear the valves,that would be my fix.

crazypj · « **Reply #23 on:** June 24, 2012, 02:27:56 PM »

Cam is probably retarded about 10 degrees.
Bike will run real well at high rpm but you will loose some bottom end
Machine valve reliefs for 0.020" clearance, get barney to do it properly, he'll have to make a fixture, luckily there are some good pics on CafeRacer.netof fixture to hold piston. It's almost identical to the one I made
http://www.caferacer.net/forum/topic.asp?TOPIC_ID=22206

MRieck · « **Reply #24 on:** June 24, 2012, 03:48:11 PM »

This is in hindsight and assumption but it would have been a good idea to grind around #4, fill with tig and then mill. Milling would have been reasonable at that point (as I assume that is what they were trying to clean up). Like I asked before....what took a walk around #4??

News:

Author Topic: Loud clicking from top end - not just a loose valve! (Read 8100 times)