Author Topic: Tappet Nightmares (video)  (Read 3342 times)

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Offline Rgconner

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Re: Tappet Nightmares (video)
« Reply #25 on: June 22, 2015, 10:52:33 PM »
Ya I set it to .002 when it was cold and it measured .004 when it was hot. I can't remember if the gap is supposed to increase with heat or decrease but my definitely increased.

It's my understanding they should decrease. Lengthening of the valve stem from heat expansion. That's why there's a larger gap on the exhaust side...more expansion shrinking the clearance.


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1978 Honda CB550K

Yes, the lash is designed to go to .000 nominal when the engine is hot.

Getting more gap hot is not logical, indicating something else is going on, up to and including mechanic error.
1975 CB550K aka "Grease Monkey"

Offline DaveBarbier

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Re: Tappet Nightmares (video)
« Reply #26 on: June 23, 2015, 04:24:22 AM »
Is this a new to you bike? Has it always made these noises or is it a new problem?


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1978 Honda CB550K

Offline Paganica

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Re: Tappet Nightmares (video)
« Reply #27 on: June 23, 2015, 07:03:01 AM »
Is this a new to you bike? Has it always made these noises or is it a new problem?

The bike is new to me. When I got it I didn't hear much tappet noise when it was running but at that time I didn't even know what tappets were. When I started to ride the bike I was getting a lot more noise when the bike was under throttle at higher rpms (~4,000). If I let off the throttle or kept it at a coasting speed the noise would go away so I did some research and found others with a similar noise related to tappets so I assumed they were out of spec and they were.

Who knows what the previous owners have done... I know there has been some work done on the bike, my valve cover has a crack running along the ear where one of the mounting screws is so I'll probably have to replace the cover once it comes off. I can only assume someone cracked it and that it was taken off at some point.

Ya I set it to .002 when it was cold and it measured .004 when it was hot. I can't remember if the gap is supposed to increase with heat or decrease but my definitely increased.

It's my understanding they should decrease. Lengthening of the valve stem from heat expansion. That's why there's a larger gap on the exhaust side...more expansion shrinking the clearance.

Yes, the lash is designed to go to .000 nominal when the engine is hot.

Getting more gap hot is not logical, indicating something else is going on, up to and including mechanic error.


I'm going to readjust this evening and run it again to see what results I get. After viewing this thread: http://forums.sohc4.net/index.php?topic=122627.0 I'm starting to wonder about wear more and more. That guys bike sounds pretty identical to mine.  :-\


Offline DaveBarbier

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Re: Tappet Nightmares (video)
« Reply #28 on: June 23, 2015, 09:57:47 AM »

my valve cover has a crack running along the ear where one of the mounting screws is so I'll probably have to replace the cover once it comes off.

http://pages.ebay.com/link/?nav=item.view&alt=web&id=400897474717&globalID=EBAY-US

I found this for another member but I don't think he needs it. Just if you decide to get a new cover, they're not crazy money. And this is the updated cover with rocker shaft pins to help eliminate the wobbling issue.


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1978 Honda CB550K

Offline Tews19

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Re: Tappet Nightmares (video)
« Reply #29 on: June 23, 2015, 10:02:29 AM »
Actually Hellraiserxl has a spare 78 550 engine. I bet you could get it from him for cheaper.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline hellraiserDLX

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Re: Tappet Nightmares (video)
« Reply #30 on: June 23, 2015, 10:06:42 AM »
I do have one if you need one. Shoot me a pm

Offline Paganica

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Re: Tappet Nightmares (video)
« Reply #31 on: June 23, 2015, 07:33:29 PM »
Alright I readjusted the tappets to spec again... About half the tappets were out of spec from my previous run. After readjusting I ran the bike again and the intake on cylinder 4 made a ton of noise again and measured .004" when hot. I closed the gap significantly while it was hot, started it up and things were a lot quieter though it did make some noise still... Probably since i didn't close it completely.  Most of the other tappets were quiet but after cooling a number of them were out of spec again and had a larger gap than they should.

Looks like I'll be needing to tear into this thing.

Offline 754

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Re: Tappet Nightmares (video)
« Reply #32 on: June 23, 2015, 08:21:45 PM »
Yeah something moving around in there.  Past the adjuster screws..... Or rarer sticky guides..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Paganica

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Re: Tappet Nightmares (video)
« Reply #33 on: June 24, 2015, 08:05:04 AM »
I do have one if you need one. Shoot me a pm

PM sent

Is there anything else I should consider replacing while I am replacing the rocker cover? O rings, seals, cam tensioner, etc?

Offline Tews19

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Re: Tappet Nightmares (video)
« Reply #34 on: June 24, 2015, 09:19:10 AM »
Cover will come off no problem. Maybe a new gasket for that but I think start with that and go from there. Hellaraiser a good dude. He will give you a fair price.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline hellraiserDLX

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Re: Tappet Nightmares (video)
« Reply #35 on: June 24, 2015, 04:07:44 PM »
PM replied to. The cover will most likely be mailed in a usps flat rate box so if there is anything else you need off the motor let me know and ill throw it all in there for free. I really dont need it anymore. Hell you can take the whole damn thing with you if you want to come get it haha

Offline Paganica

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Re: Tappet Nightmares (video)
« Reply #36 on: July 18, 2015, 11:35:31 AM »
Alright so a quick update. I finally pulled the cover and have posted some pics. It looks like my first and fourth cylinder (which actually seemed to be making the most noise) have burn marks on the tappets. I don't know if this is normal or if they weren't getting oil or something like that.

You can also see the broken corner of the cover. I will be swapping the cover and the rockers as well since my rockers look worse. I  haven't pulled the arms out so I don't know if the holes have ovaled out any but will post pics when I do. If they are still pretty round then I will be clueless as to where the tappet noises have been coming from.
« Last Edit: July 18, 2015, 02:03:59 PM by Paganica »