Author Topic: Frequent #1 intake tappet adjustment.... (Read 3102 times)

joeyvans · « **on:** May 26, 2016, 08:19:25 AM »

Wanted to see if anybody had a theory on my slight issue....

'76 CB550K - no known go-fast motor bits.

I have found that I need to adjust my #1 intake tappet quite frequently. But, only the #1 intake... never the exhaust. After every few rides.... it starts to develop a slight tick which can be cured by readjusting (specifically, tightening or turning in) the tappet screw when the engine is cold. With the next startup, it sounds like a sewing machine again. I have been tightening down the tappet lock nut probably tighter than I should because I was concerned that was the problem. But, it appears this problem isn't going away.

I haven't had a chance yet, but I think I will pull the nut and screw and check the bottom for damage, excessive wear, etc.

Does anybody have any thoughts on the cause of this issue? Problem with the rocker?

Thanks

Kyle

flybox1 · « **Reply #1 on:** May 26, 2016, 08:29:13 AM »

Good idea to pull the nut and screw.
I would think that continued over-tightening of the lock nut would eventually smooth out its locking 'surface' making it more susceptible to unlocking. Post a picture of what you find....

754 · « **Reply #2 on:** May 26, 2016, 08:46:43 AM »

Might be cam lobe going, or tip of valve is cratering...wearing off.

strynboen · « **Reply #3 on:** May 26, 2016, 08:55:45 AM »

its the valve/arm shaft..vho veares the valve cover..make oval holes ,so the shaft can move a lot araund..and then the valve adjusting geta schreved up..in sekunds after start..
you need a valve cover from a later engine k3 77-78..vill fit...they have fixed shafts..so no vearing aut the bores...

make a searge..its a common faulire

joeyvans · « **Reply #4 on:** May 26, 2016, 08:59:32 AM »

Thanks gents! I will dig in and see what I can find and report back with pictures.

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754 · « **Reply #5 on:** May 26, 2016, 09:52:25 AM »

You can pull tappets cover and see if its getting oil, should be oily. . If dry not good .I suspect a worn guide could also cause frequent adjustment

joeyvans · « **Reply #6 on:** May 26, 2016, 10:00:26 AM »

Quote from: 754 on May 26, 2016, 09:52:25 AM

You can pull tappets cover and see if its getting oil, should be oily. . If dry not good .I suspect a worn guide could also cause frequent adjustment

Oil delivery is good... Never dry.

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BomberMann650 · « **Reply #7 on:** May 26, 2016, 10:44:57 AM »

I just went thru the same issue on my 75 550F
Like styrnboen mentioned, rocker arm shafts wore an oval hole in the head cover. Resulted in frequent tappet adjustments.

Oddly, it was only the intake side that got buggered up.

Heres what my problem looked like after taking the cam covers off the sides of the head.

First photo is bad alignment, second photo is proper.

joeyvans · « **Reply #8 on:** May 26, 2016, 11:10:38 AM »

Thanks Bomber! So you swapped the valve cover for a '77 or '78?

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Duanob · « **Reply #9 on:** May 26, 2016, 01:38:11 PM »

Even 76' had the updated cam cover. Look for four studs underneath the breather cover as well as four bolt holes. The old style only had the four bolt holes. See below.

joeyvans · « **Reply #10 on:** May 26, 2016, 01:41:33 PM »

Yeah... Read that later '76's got the updated cover. Will dig in over the weekend. Thanks!

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BomberMann650 · « **Reply #11 on:** May 26, 2016, 02:48:38 PM »

Quote from: joeyvans on May 26, 2016, 11:10:38 AM

Thanks Bomber! So you swapped the valve cover for a '77 or '78?

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I got lucky and scored on a mostly complete 77 k motor.

But whoever said "don't use gasket sealer at the valve cover o-ring" owes me an engine detailing and a bottle of castrol

Should of applied the ht sealant like I did before.

I suppose it's also worth mentioning, the rocker arms left some uneven wear on the cam labes, so I swapped the cam out too. Since I had a spare to spare.

joeyvans · « **Reply #12 on:** May 26, 2016, 02:51:40 PM »

Ok. Judging by the looks of things, these updated covers are hard to find.

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BomberMann650 · « **Reply #13 on:** May 26, 2016, 02:53:33 PM »

Strynboen described a repair/modification that can be done to the rockerboxes. Requires machining and making bushings .

joeyvans · « **Reply #14 on:** May 30, 2016, 02:57:56 PM »

It appears that the Island Dane and Bomber were correct with their theories.

Pic #1 confirms that I have the earlier valve cover.
Pic #2 shows the rocker shafts on #4 are lined up well still.
Pic #3 shows the rocker shafts on #1 are different.... the exhaust shaft still looks good... not the intake.
Pic #4 shows the exhaust rocker shaft on #1 close up. It looks like it has good alignment.
Pic #5 shows the intake rocker shaft on #1 close up. It appears to be in bad alignment.

Now, do you fellas advise that I discontinue running the motor until I can come up with a replacement cover? Or... can I run it this summer and address the issue during the off season? I had only planned on between 1000 and 2000 miles on this summer. I don't commute with it... and typically only ride 50 to 150 miles/week. Just want some opinions on how to proceed.

Thanks again, guys! I appreciate you pointing me in the right direction.

Kyle

BomberMann650 · « **Reply #15 on:** May 30, 2016, 07:26:44 PM »

I'd replace it ASAP - even if you get another pre '77 failure-prone one.

Or else you WILL need a new camshaft too, if that isn't already the case.

What is it about the intake shafts on these?!

joeyvans · « **Reply #16 on:** May 30, 2016, 07:46:48 PM »

Roger that! I will start keeping my eye out for a cover. Aside from o-rings, breather cover gasket and valve cover gasket.... is there anything else I should replace while I'm in there?

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BomberMann650 · « **Reply #17 on:** May 30, 2016, 08:24:44 PM »

Thats about it, tho I managed to mangle a few tappet covers in the removal process. That cost me some knuckle skin too.

Otherwise, it's up to you how far you wanna go down the rabbit hole.

tennesseebreeze · « **Reply #18 on:** June 01, 2016, 07:27:45 AM »

I'm getting the same ticking valves after adjustment on my '72 cb500. I didn't know if the ticking was normal or not. My valves and seats were re-cut due to pitting. The machinist also ground a little off the valve stem end to compensate for the valve sitting higher in the cylinder head. Seemed logical at the time, but maybe the ticking is related to this. I'm going to check out my tappet shafts for this problem. I'm hoping I don't need a replacement cover too.

alacrity · « **Reply #19 on:** June 01, 2016, 12:52:20 PM »

Quote from: tennesseebreeze on June 01, 2016, 07:27:45 AM

I'm getting the same ticking valves after adjustment on my '72 cb500. I didn't know if the ticking was normal or not. My valves and seats were re-cut due to pitting. The machinist also ground a little off the valve stem end to compensate for the valve sitting higher in the cylinder head. Seemed logical at the time, but maybe the ticking is related to this. I'm going to check out my tappet shafts for this problem. I'm hoping I don't need a replacement cover too.

You can file/machine down the valve stem ends to make them flat/shaped as OEM... you can file/machine down the ends of the adjuster studs that thread into the rockers (if you keep both within "spec" so that you have enough "throw" to get them adjusted properly. These also need to have the OEM edge "shape" which if i recall isn't perfectly flat but edge-beveled or curved slightly since they contact the valve stem ends at an angle. IF you have these "eccentric" in any way, a slight adjustment change will get them to ride up or down, changing the relative gap. If these "walk" at all when the bike runs, heats, cools then the gap changes that way too.

I would also recommend "facing" all valve stem ends identically and then weighing them to be sure they are the same. Heavier valves will react to a certain spring pressure differently than lighter ones (of course this assumes all your spring sets are identical, which is probably not the case after 40 years of compression... )

So in answer to your actual question: NO, probably its sloppy rocker shaft tunnels (which get sloppier as the engine heats and the aluminum cal head cover expands relative to the steel less-heat-sensitive shafts) and/or sloppy rocker FIT on the hardened shafts and/or (least likely) very slight bent shafts. AND note that you can exacerbate the rocker shaft slap by having slightly bent valve -- it doesn't want to pop open as easily, creating extra friction/drag/pressure on the rocker, which in turns creates angular pressure on the shaft, which then pushes hard into sidewall of the aluminum shaft tunnel, which gets softer with heat = gall.

joeyvans · « **Reply #20 on:** June 01, 2016, 01:01:55 PM »

I can't find any '77 or '78 covers currently, but am going to look at a couple '74 motors. Hopefully neither one has issues currently so I can continue riding until I can find a late model cover.

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BomberMann650 · « **Reply #21 on:** June 01, 2016, 02:34:18 PM »

Quote from: joeyvans on June 01, 2016, 01:01:55 PM

I can't find any '77 or '78 covers currently, but am going to look at a couple '74 motors. Hopefully neither one has issues currently so I can continue riding until I can find a late model cover.

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Happy Hunting!

Someone mentioned to me that 12-15,000 miles was about the lifespan of the pre 76 rockerbox assembly. Hopefully those spare motors have low miles - and you know what to look for under the cover to determine if the part you're after is usable.

Good Luck and Godspeed

joeyvans · « **Reply #22 on:** June 01, 2016, 02:38:58 PM »

It's between 12 & 13, so I might be sol. But it is cheap enough where a part out might be worth the while even if the cover is shot.

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BomberMann650 · « **Reply #23 on:** June 01, 2016, 02:41:31 PM »

Quote from: joeyvans on June 01, 2016, 02:38:58 PM

It's between 12 & 13, so I might be sol. But it is cheap enough where a part out might be worth the while even if the cover is shot.

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Welcome to Parts Hoarders Anonymous

My spare cost $100 - turned over and had modest compression. Hopefully you can get a deal like that too!

Gene · « **Reply #24 on:** June 01, 2016, 06:16:10 PM »

Commenting just so this is "bookmarked".

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Author Topic: Frequent #1 intake tappet adjustment.... (Read 3102 times)