New owner of a 1982 CB750K

[SurferD]

Just introducing myself on this board.
I just bought this bike and can't wait to get it going.
I paid $500 for it.
The P.O. has had it since 1989 and was the second owner.
He only drove it 1200 miles in all that time.
It has 8443 miles on the odo.
Generally it's in great shape and only has some surface corrosion excpt for the wheels which have some heavy rust.

He parked it for a long time then put a in a new battery, tires, and had the carbs serviced.
He drove it a few times and parked it again for 5 years prior to me buying it, of course with fuel in the tank and petcock on.
I will be going over needed maintenance/repairs.
I put a new battery in today and pleasantly found all the lights and turn signals work
The original complete toolkit and owners manual were also in the cubby.
I still have to drain the fuel from the tanks and carbs, fog the cylinders and check compression so I don't dare trying to start it yet.
I'll probably send the carbs to Mike at cb1100fcarbs.com for refurbishing.

 

[SurferD]

Some questions on operation of the lights:
The brake light only comes on with the front lever not the rear pedal.
The front side running lights are constantly on and flash with the signal button but the rears only light up with the signals.
Are both of these normal situations?

 

[amc49]

The second is, the first is not. The rear brake works the light too, there is a switch somewhere slightly above brake pedal attached to a frame tube.

Bike has front running lights but not rear, only double bulb taillight.

 

[SurferD]

The second is, the first is not. The rear brake works the light too, there is a switch somewhere slightly above brake pedal attached to a frame tube.

Bike has front running lights but not rear, only double bulb taillight.

Ok I'll look for that switch thanks

 

[SurferD]

It was simple adjustment.

 

[SurferD]

Any recommendations on motor oil?
Conventional, synthetic, Honda brand, regular car oil?

 

[amc49]

Oil is oil my view, I've heard the thousand arguments over it. 10W-40 or 20W-50 if motor old or a racer. I used to use straight 30 in winter and 40 in summer and couldn't kill the motors.

Just DON'T use car oil, they have removed the zinc and the 'friction modifiers' that replaced it are slick enough to cause DOHC starter one way clutches to start slipping to not lock up. Use a JASO qualified oil with some zinc in it, that commonly means using a motorcycle specific oil.

 

[SurferD]

Yes I will definitely get bike specific. I have a 70 Datsun 240Z and I use a zinc additive in the oil.
I'll stick with the manual recommended 10w40 for viscosity.
Thanks

 

[The Jimbonaut]

Hey Surfer, very nice ride - a couple of weeks ago I bought myself an '81, same model as yours so you and I are on the same page =)

Previous owner had let it sit for a couple of years - I cleaned out the carbs (not a thorough clean but man, the float bowls were totally bunged up with rust - from the tank - and god knows what else), checked and cleaned the fuel lines and air box, new battery and new gas in the tank...I'll be darned but got the old girl running. I'm no mechanic (this is my first restoration/build) but it's a blast having a go. Good luck with everything - maybe you and I can help each other out from time to time even if it's just with a supportive beer =)

Later,

-J

 

[SurferD]

Hey Surfer, very nice ride - a couple of weeks ago I bought myself an '81, same model as yours so you and I are on the same page =)

Previous owner had let it sit for a couple of years - I cleaned out the carbs (not a thorough clean but man, the float bowls were totally bunged up with rust - from the tank - and god knows what else), checked and cleaned the fuel lines and air box, new battery and new gas in the tank...I'll be darned but got the old girl running. I'm no mechanic (this is my first restoration/build) but it's a blast having a go. Good luck with everything - maybe you and I can help each other out from time to time even if it's just with a supportive beer =)

Later,

-J

Seems like we are. How much did you pay for it?
I saw yours, I like the white.
It was rust not varnish in your bowls?
Today I changed the oil/filter, took out the plugs and sprayed the cylinders. then cranked it over a few times with the starter.
Then put in the plugs and put some new gas in and tried it. I Pulled the choke and it sputtered then after a few more tries, nothing.
So I will be taking off the carbs after all. I think the last time it ran was 2009 because that's the date on the tires and the PO said he replaced them then.
Would that beer be a Molson?

 

[The Jimbonaut]

Paid $425 for mine- the white is a respray, not a bad job but won't be around for long. Someone welded an extra set of pegs just behind the side covers so they'll be coming off, and sadly they chewed into the side covers themselves, but as I'm doing a brat build I'm not too fussed.

Pretty sure it was rust - same colour and the inside of the tank looks a little rusty too. Not terrible, but will need a clean that's for sure.

Getting the carbs out was not a biggy, in fact I really enjoyed the whole process. I like stuff like that I guess. Here's a useful video that helped me out no end -

https://www.youtube.com/watch?v=5zlu1RvA2Nk

Make sure you get the gaskets off the float bowls if you're planning on spraying carb cleaner in there, that stuff'll warp them in no time. Here's a vid on how to clean them that's pretty easy to follow -

https://www.youtube.com/watch?v=dD3UWtLfzX4&t=1149s

My carbs (and yours I guess) are a little different from those shown in the vid, but from what I could tell the principles are pretty similar. When you unscrew the jets, make sure you make a note of the little number engraved onto the sides - the jets look identical but the holes are different sizes. You'll want to make sure the right jet goes back in the right hole. Have a go mate, it's not that hard =)

Once I'd cleaned mine (I just did a once over - once I'm sure the engine is tip top then I'll be rebuilding the carbs completely) and connected them back up, with a bit of throttle persuasion I got the old girl roaring into life. One thing I learned along the way - the '81 has a vacuum thingy on the fuel line, and this can interfere with the initial gas feed into the carbs. So, upon hearing that sometimes this vacuum can prevent gas from entering the carbs, before I put the carbs back together I poured a little gas into each float bowl before reattaching them. That way you know you have some gas in the bowls when you go to start it up. Worked for me =)

Rock n roll,

-J

 

[The Jimbonaut]

By the way, what exactly is "spraying the cylinders"? I haven't done that, but sounds like I should...

 

[SurferD]

By the way, what exactly is "spraying the cylinders"? I haven't done that, but sounds like I should...

When you store any engine you usually "fog" or oil the cylinders to prevent corossion. Remove the plugs and pour 1 tablespoon of oil or spray with a preservative fogger.
Then rotate the crank with the starter or by hand to distribute the oil.
If that hasn't been done then there's a chance your cylinders could rust and pistons seize.
One way to help get them moving after sitting is spraying with fogger or just WD40
(which actually removes oils ironically) to lube it up a bit.
No need to do it now since yours is running.

 

[amc49]

Look for 'fogging oil' at the boat supply place..........................or simply cut regular oil a bit with fuel to lower the thickness and spray with a spray bottle in intake while whirling the engine around with starter. You may have to change plugs at next season from them fouled out with oil. A normal cost of winterizing. Don't forget Stabil fuel stabilizer in any fuel left in bike.

 

[SurferD]

Got the carbs out. That video was helpful. I took it out of the right side though since the bracket for the choke cable was in the way.. They look very clean and no corrosion at all. Tomorrow I'll look them over for obvious varnish buildup. Are the carb to head boots supposed the be soft and pliable or stiff? Mine are really stiff.

 

[The Jimbonaut]

Kudos on the carb job =). The carb to airbox boots are shot on mine - one was torn and the other three are really stiff. I'll be buying a new set, you can pick them up for around $50. The carb to head boots on mine ain't going anywhere, mine are stiff and staying that way

 

[SurferD]

Yea I just scored a genuine Honda set on eBay for 57.30 shipped

 

[The Jimbonaut]

Good find - are you planning on rebuilding the carbs as well? Some of the jets in mine, along with the gaskets, were in pretty rough shape so I'll need some rebuild kits. From what I've read Randakk's kits are rated very highly.

I ran into another snafu yesterday trying to remove the engine cover over the timing plate - the three screws holding it in place were totally rusted out and almost stripped. I managed to get two out with an impact driver but the third is not coming without a fight. The Philips head is totally shot so I'm gonna try knocking in a new head with a chisel and see if the driver will have more luck with more to bite into

 

[SurferD]

Not sure yet about rebuilding. I need to look at it and see if it just needs cleaning.
If you have a Dremel use a cut off disk to make the new slot instead of a chisel.

 

[The Jimbonaut]

Got the little bugger! Drilled out enough of the screw with a 1/8" drill bit, hammered in a screw extractor and got it out of there with a tap wrench

Smells like...victory