Author Topic: 1980 CB750C engine noise, and what year(s) SOHC most desirable? (Read 6157 times)

daveg · « **on:** October 17, 2006, 08:09:34 PM »

This is a great forum! I joined as soon as I found it!

Okay, here is my story (short version). I have been wanting a bike. Not sure what really. Walked around my block a few weeks ago, and there it was. A motorcycle!! Okay, it was a Honda. They make good bikes, right? Might as well get it. Hey, its a 1980 CB750C, whaddyaknow!! So, I pick it up for $600. New tires, rebuilt carbs, and new battery. Can't go too far wrong, right? Well, I did find out the chain and sprockets were shot. New ones coming. The problem that really bugs me now....at 1000 rpm idle, the engine has a lot of "clunking" sounds coming from it. I speed it up to 1300-1500 rpm, and the clunking goes away and sounds great. Could my problem be the cam chain or some sort of tensioner? I have read some things about the '79-'82's having some "issues" in this area. Is this a hard fix?

Also, since learning about my '80 and the DOHC engine, I really wish I would have found an older SOHC CB750 F Super Sport. I saw one in the Chicago area today. It caught my eye from 1/2 mile away!! Sharp!! Are there certain years that were grouped together in terms of engineeing changes or certain years that are more sought after? I will probably end up selling the '80 once I have "cut my teeth" on it and come up the learning curve. Any help or advice you guys can give a DOHC newbie would be appreciated.

Thanks!

Dave

kghost · « **Reply #1 on:** October 17, 2006, 09:26:39 PM »

1969 aka the sandcasts.......

Do a search on this forum about sandcast.

mrbreeze · « **Reply #2 on:** October 18, 2006, 02:06:04 AM »

You came to the right place with the wrong bike!!!!! There are forums(I guess) for the DOHCs but this ain't it.When you off-load that one and score an SOHC,come on down and we will learn you up!!!! There is a section here for other bikes though and maybe someone will give you some info(not me.....sorry!!!)

SteveD CB500F · « **Reply #3 on:** October 18, 2006, 02:50:45 AM »

DOHC Forums are at:

www.cb900c.net

www.cb1100f.net

Don't be fooled by the names - they accept any Honda DOHC!

eldar · « **Reply #4 on:** October 18, 2006, 10:44:47 AM »

Some say the sandcast is most sought after but thats just cause they have not ridden a 78!

kghost · « **Reply #5 on:** October 18, 2006, 12:28:12 PM »

Quote from: eldar, Master of the K8 Thunder! on October 18, 2006, 10:44:47 AM

Some say the sandcast is most sought after but thats just cause they have not ridden a 78!

Sure

Then ya woke up

bill440cars · « **Reply #6 on:** October 18, 2006, 01:47:23 PM »

Quote from: SteveD CB500F on October 18, 2006, 02:50:45 AM

DOHC Forums are at:

www.cb900c.net

www.cb1100f.net

Don't be fooled by the names - they accept any Honda DOHC!

Hey Steve, I've been to both of those sites and I can tell you that the "F" site will accept them but, they don't want to hear any reference to the "K" model. I have an 80' CB750K and as long as I don't mention that it is a "K", there's no problem. So, I'm beginning to think that the DOHC CB750K is the biggest Black Sheep of all (even more so than the CB650)! Now that 750C will be totally welcome at the cb900c.net site but, I don't know so much about the F site. Just my own experiences. You know, while it isn't a SOHC, the DOHC is a pretty good runner on it's own.

Later on, Bill

mrbreeze · « **Reply #7 on:** October 18, 2006, 06:43:32 PM »

Kghost.....ditto!!!

dusterdude · « **Reply #8 on:** October 19, 2006, 10:42:28 AM »

Quote from: kghost on October 18, 2006, 12:28:12 PM

Quote from: eldar, Master of the K8 Thunder! on October 18, 2006, 10:44:47 AM
Some say the sandcast is most sought after but thats just cause they have not ridden a 78!

Sure Then ya woke up

hahahahahahaha,now that was funny.

ofreen · « **Reply #9 on:** October 19, 2006, 02:01:22 PM »

Quote from: daveg on October 17, 2006, 08:09:34 PM

I really wish I would have found an older SOHC CB750 F Super Sport.

It is pretty much accepted by all (except the envious) that the '75 750F is the crown jewel of SOHCs.

mrbreeze · « **Reply #10 on:** October 19, 2006, 02:10:14 PM »

Except for us K owners!!!

ofreen · « **Reply #11 on:** October 19, 2006, 02:18:40 PM »

Quote from: mrbreeze on October 19, 2006, 02:10:14 PM

Except for us K owners!!!

Like I said, except the envious.

mrbreeze · « **Reply #12 on:** October 19, 2006, 02:51:48 PM »

eldar · « **Reply #13 on:** October 20, 2006, 08:16:33 PM »

The envious drive K1s!

Gregorymoto · « **Reply #14 on:** October 27, 2006, 09:14:23 PM »

You need to tune your top end. Valves and such, you should take it to a shop it is a shim system a little hard on the head of a beginner .
Good luck, Gregory N. Mountain

angeldeville · « **Reply #15 on:** October 27, 2006, 10:26:56 PM »

Quote from: ofreen on October 19, 2006, 02:01:22 PM

Quote from: daveg on October 17, 2006, 08:09:34 PM
I really wish I would have found an older SOHC CB750 F Super Sport.

It is pretty much accepted by all (except the envious) that the '75 750F is the crown jewel of SOHCs.

Oops, I think you meant to type in '76, your finger must have slipped....

Dave good luck with your DOHC, and when you finally get your SOHC just make sure it isn't a K8 and you should be fine....

Check out my gallery link for a couple cool F's, The red is a '78 and the teal is a '76

eurban · « **Reply #16 on:** October 28, 2006, 09:17:49 AM »

As to the fellows question about the engine ruckus. Quite likely its the typical clutch basket/ primary chain rattle that the SOHCs and the DOHCs suffer from. Certainly you should adjust the cam chain and valve clearances but if the noise occurs when the bike is idling in neutral, disappears when reved and when clutch is pulled in, then its the afore mentioned clutch/primary rattle. Not really much to worry about, but properly functioning and synchronized carbs will help to reduce is not eliminate most of the rukus. Good luck.

BobbyR · « **Reply #17 on:** November 01, 2006, 05:09:16 PM »

Quote from: bill440cars on October 18, 2006, 01:47:23 PM

Quote from: SteveD CB500F on October 18, 2006, 02:50:45 AM
DOHC Forums are at:

www.cb900c.net

www.cb1100f.net

Don't be fooled by the names - they accept any Honda DOHC!

Hey Steve, I've been to both of those sites and I can tell you that the "F" site will accept them but, they don't want to hear any reference to the "K" model. I have an 80' CB750K and as long as I don't mention that it is a "K", there's no problem. So, I'm beginning to think that the DOHC CB750K is the biggest Black Sheep of all (even more so than the CB650)! Now that 750C will be totally welcome at the cb900c.net site but, I don't know so much about the F site. Just my own experiences. You know, while it isn't a SOHC, the DOHC is a pretty good runner on it's own.

Later on, Bill

I would say stay away from bigots. The king of all 750s is the 1978. They ironed out all of the earlier mistakes and reached perfection. Then they made the DOHC and the rest is a sordid tale in Honda history.

sparty · « **Reply #18 on:** November 01, 2006, 05:34:22 PM »

Actually, the most desirable are the CR SOHC bikes. They cost big $$$$ with lots of zeros at the end.

Sparty

BobbyR · « **Reply #19 on:** November 01, 2006, 05:48:40 PM »

OK Sparty ya got me.

I was of course speaking of those bikes the average Joe could lay his hands on.

sparty · « **Reply #20 on:** November 01, 2006, 06:21:22 PM »

Quote from: BobbyR on November 01, 2006, 05:48:40 PM

OK Sparty ya got me. I was of course speaking of those bikes the average Joe could lay his hands on.

Yeah, I know, but I had to throw that out there for everyone.

Sparty

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Author Topic: 1980 CB750C engine noise, and what year(s) SOHC most desirable? (Read 6157 times)

daveg

eldar

eldar