My 1981 CB750k - just starting out

[qu1kb1rd]

A buddy at work gave me this bike for $200 on the condition that he gets to ride it occasionally "If I can get it running again". I plan to restore it as close to "new-old stock" as I can.

Here's a link to the "before" pics from the day I trailered it home.

CB 750k 'before' pics

Buddy had been riding this bike to work sometimes over about a 5 year period, so I know it used to run ok. The chain jumped off one day and he parked it for two years before selling to me. With a new battery, it cranked and turned over just fine, but wouldn't fire. I figured carbs just needed a good cleaning.

So far, I have mainly gone through and assessed the jobs needed and started ordering parts. I've taken some WD-40, some brake parts cleaner and some carb cleaner and gotten the first layer of crust off most things.
I took the carbs off and went through them a couple of times and I think they are reasonably clean and ready to go. In the next week or two, I'll clean out the gas tank and try to get this thing running again before i really dive into the other things it needs. If all goes well with that, I'll consider the cosmetic stuff.

I plan to get it running with stock airbox and stock tune. I did buy some pod filters and a jet kit, but after reading around the internet, I'm not sure about trying to jet/tune these carbs, seems most people fail at it and I'm not an ace wrench. In fact I've never worked on carbs before now. Still, part of me is thinking 'how hard can it really be?'.. famous last words I know :-)

Anyway, I've enjoyed reading the tips and threads on the site and look forward to posting more as this bike comes back to life.

[TOOLS1]

Welcome to the forum. Not bad, for $200.00. I would look into why that tire wore out on one side.
TOOLS

[shinyribs]

 Thats really not a bad lookin' ride! You sound like you are on the right path. You really dont need to be a master mechanic with these bikes. They are super easy to understand and work on. There a few drawbacks to pods. Getting them jetted right is really not bad at all. If I figured it out, I'm sure anyone can. The only advice/warning on pods is that they act awful on a windy day. I have caught a few hard side drafts with mine and it will just about kill the bike. I would seriously say it feels like it cuts the power down to about 30%. Seriously. Anywho,good luck with your project. Looks like fun! Good to have you!

Oh,that tire does look a lil scary. I didnt even know you could do that to a motorcycle tireThat would definitely be my JOB #1

[seestheday]

I would definitely look into why that tire wore out on one side and absolutely get a new one before doing any riding.  You only have 2.  A blowout at speed for a novice rider is very dangerous.  The chain jumping is also pretty scary.  Was it super loose?  Is there an alignment problem?

Shiny, regarding the carbs - you have an SOHC, this is a DOHC.  From what I understand the carbs are very different between models and only the DOHC ones have the issues with the pods.

[shinyribs]

Yep. You are exactly right Sees'. I really need to pay better attention! See?...the resident cv carb expert has struck again!But a side draft will kill a sohc with pods. I can unfortunately attest to that

[Re-run]

A lot of people get bitten by the carbs. They seem simple but don't let them fool you.
Anyways Welcome to our little home and don't forget to get the service manual here.

[qu1kb1rd]

Thanks for the welcome, all!

First off, I wouldn't dream of taking this bike on the road on these tires. I'm shocked the P.O. let them get to this state. Sadly, lots of the bike reflects this level of (non) care-taking. This is probably why the chain jumped off as well, it had to have been stretched out badly and the sprockets are worn out. I'd be perfectly willing to bet he never lubed the chain once nor adjusted it.

I've got a decent amount of riding experience, I've done about 60,000 miles on two wheels in the last 5-6 years, but wrenching not as much. I did have a 1985 Shadow 700 for a while that I did a fork rebuild and some other jobs to, but it was in great shape relative to this CB750k, and basically ran great. Gotta love those old Hondas. These engines just won't die!

Got the carbs pretty clean, cleaned out the tank by sloshing some seafoam around and draining it.  Remounted everything and tried to fire 'er up, to no avail. Didn't seem like gas was getting into the floats, so I opened up a float bowl drain and... nothing. I got some theories to check out:
1- float level is set wrong so the valve is closed and no fuel getting in.
2- something nasty in the lines that's blocking them up
3- the auto-petcock fuel diaphragm thingy is boogered up

That's the state of things, again thanks for the welcomes. Hopefully I can post a vid of this thing running soon!

-Qu1kb1rd

[qu1kb1rd]

Finally made some time to work on the CB750. It's running now!

Here's a short vid of it running: It lives!

The float heights weren't set right, so very little fuel was getting into the bowls.

Also the auto-petcock thingy wasn't letting any fuel through, so I took it out. I'll just have to remember to close the petcock manually from now on.

Pretty good milestone, glad to finally get it running ok.
Now I can start in on making this bike a rider again.

Thanks!
Qu1kb1rd

[shinyribs]

Looks like she revs good! Progress,cool! Keep up the good work!