Inherited my dad's 1980CB750K

Posted: Mon Jun 15, 2020 1:06 am

Hey guys.
Just joined the site after a member in the CB750 Facebook group sent me this way. Super pumped to be apart of this community and I hope I'll be able to contribute my part.

I also would love comments and direction for those of you that are familiar with the issues I'm working through (on the bike of course...lol). I also plan to scour the forum since I'm pretty sure I'm not the first guy to encounter my list below, so I'm not that new guy who posts a question when the answers are all already there.

I inherited my dad's 1980 CB750K. It's been sitting for 7 or 8 years, had a shed collapse on it and was just plain neglected. It was stored under cover (collapsed shed) but it was out of the weather. I'm working through all the issues that I've seen so far, which is proving to be more and more as I spend more time on it. My list so far
-cosmetic damage and fuel tank dent repaired from the shed collapse
-starter clutch upgraded to 2013 R6 assembly since a rebuild didn't fix that awful noise and it still wouldn't turn over.
-front caliper rebuilt
-new front brake line
-new front master cylinder
-steering tube bearing replaced

On the agenda:
-new ignition wires
-new iridium spark plugs
-new spark plug caps
-inline fuel filter

Problem's I don't yet have a solution for (still haven't looked through the forums yet, but I will):
-forks are scored and worn through the outer layers on the inner sides

Things I've been told to look at, but I haven't gotten to yet
-chain (o-rings rot and might be no good)
-valve clearance (don't have the specs or procedure for this)
-valve chain tension (don't have specs or procedure for this)

I think first on my list will be the valve adjustment and chain tension (unless otherwise suggested) since I've already got the tank off for repairs to it, and I plan to do all the spark plugs & wires.

Let me know what you guys think and thanks for having me.

Posted: Mon Jun 15, 2020 7:18 am

Welcome to the site kbroen ... Smile

Looks like you're on the right road .

Valves first , as almost all other motor functions are 'based' on correctly gaped and functioning valves .
.005"+/- .001" (ALL).
And , the best time to tighten the cam chains is when the valve cover is removed . Allows you to apply a bit more tension than just the springs , which 'might' be a little tired . Not to mention being able to see that they are actually tightened properly .

Good luck and post some pics of what you have , like the worn forks and anything else that would be better seen than said . Wink

Posted: Mon Jun 15, 2020 2:29 pm

Posted: Sun Jun 21, 2020 9:01 pm

Thanks.

Valve clearance is all within factory spec when I check the manual. So I feel like I lucked out there.

pd750 wrote:

And , the best time to tighten the cam chains is when the valve cover is removed . Allows you to apply a bit more tension than just the springs , which 'might' be a little tired . Not to mention being able to see that they are actually tightened properly .

When you refer to apply a little more tension, how would you go about that? What I read in the manual is loosen the locknut while engine is idling, turn the screw in and retighten locknut since it automatically sets the tension.

To me, (not versed in this system), that seems wierd or not effective enough. I'm used to applying a lot of tension and then locking it in somehow when working on a lot of automotive applications.

I'll also get pics of the fork tubes up hopefully tomorrow. Keep forgetting to get them.

I've also decided to take the entire rear end apart to check things over, I'm at the wheel bearing retainer part now, so I'm looking that all up to make sure I do it right. I can't believe the amount of chain lube that's coating everything. I don't think it's ever been cleaned.

Posted: Sun Jun 21, 2020 10:16 pm

Welcome here kbroen.

Here's some info on cam chain adjustments:

http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&p=359425#359425

http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&p=231538&highlight=dynamic+static#231538