Topic: 1972 CB 750 restoration after a 40 year nap

[mrbreeze]

7 qts.? WOW! The whole shebang only holds around 3.5! Doubt any moisture crept into that crankcase!

[autotec]

7 qts.? WOW! The whole shebang only holds around 3.5! Doubt any moisture crept into that crankcase!

7 qts was just a guess, but I'm thinking I wasn't too far off. My truck takes 6 and the drain pan level was higher with draining the bike. It does kick over ALOT easier now that the crankcase is empty. I'm thinking it was almost hydolocked with oil. Last time I seen something like this was when a car got towed in after the person tried to change their own oil. She filled the engine up to the top of the valve cover.

[754]

It leaks past the checkvalve while sitting for long periods of time.
 Then you check the tank and it looks dry, so its easy to add 3  qts over time..
Easier than pickng up the 3 qts off the ground, had you started it up...

[mrbreeze]

7 qts.? WOW! The whole shebang only holds around 3.5! Doubt any moisture crept into that crankcase!

7 qts was just a guess, but I'm thinking I wasn't too far off. My truck takes 6 and the drain pan level was higher with draining the bike. It does kick over ALOT easier now that the crankcase is empty. I'm thinking it was almost hydolocked with oil. Last time I seen something like this was when a car got towed in after the person tried to change their own oil. She filled the engine up to the top of the valve cover.

Back in the late 70's my sister-in-law had this old Buick that she lost the dipstick on. I kept telling her to go to the wrecking yard and get another one from a car with the same engine. She kept putting it off and every time I asked about it she would say she will get one. One day she was at our house and I noticed that her car was dripping oil on my driveway. Sure enough.....she still hadn't replaced the dipstick. I told her I was going to change her oil myself. I don't know how many qts. came out but it overflowed my drain pan! She said she had just been adding some every now and then. I personally took her to the wrecking yard and we got her a dip stick. I then schooled her on how important it was to maintain the oil level and made sure she knew how to check it. I guess too much was better than not enough.

[autotec]

It does kick over ALOT easier now that the crankcase is empty.

I hope you put some back in before starting the motor or kicking it over? 

Of course, I just didn't want to start it with the old oil in it. Figure i'll fill her up and kick it until I see oil on the top end.

[edwardmorris]

............

Of course, I just didn't want to start it with the old oil in it. Figure i'll fill her up and kick it until I see oil on the top end.

With the plugs out

Takes about 20-25 good kicks with 15w40 oil (from when I did mine).

[autotec]

Just a little update.... I'm trying to balance this project with a bathroom remodel that is needed in our second bathroom, so spare cash has been a little tight. But I was able to order the floats, float setting tool, air filter and a new right side switch assembly tonight. ( I can't believe how much this bathroom is costing me ) If all goes well with shipping, I should be able to start this bike this weekend just to make sure everything functions as it should. I'll be sure to post a video. After it starts, I will continue tearing it down for the rest of the work.

Thanks, Justin

[autotec]

I'm guessing it's a bad sign when the Forum warns me that this topic hasn't been replied to in more than 90 days, but it's been a cold Winter. I did manage to take advantage of a couple of unseasonable days here in WI and assemble the carbs. I was hoping to start it today, but every store I stopped at was sold out of the battery I need for it. I never did get around to needing the battery, so it was for the best.

I did run into a few problems when installing the floats and setting their heights. At first I caught myself bouncing back and forth with the height until I realized the needle "tang" was springing back slightly. After I figured that out, I just waited a few minutes in between adjustments and it went fine.

Second problem was with the cylinder 3 float posts. I'm not sure if it was myself who tweaked one of them or if it was that way, but one of them was slightly out of alignment to the point where the float pin wouldn't slide easily into both posts. (all of the pins didn't come out easily) I didn't feel comfortable "tweaking" the post back, so I reamed the holes a few thousands so the pin would slide in easy. It wasn't much, just enough. I just didn't want to break the post.

Below are some pictures since everyone likes them. LOL.

 

[EMac]

I'll be watching with interest as you get it running and continue any restoration.  I just picked up this K2 and will be starting the process myself (with a little more paint work on the tank/covers than you!).  Good luck with yours.

[autotec]

I'll be watching with interest as you get it running and continue any restoration.  I just picked up this K2 and will be starting the process myself (with a little more paint work on the tank/covers than you!).  Good luck with yours.

Thank you, it's just about to get good.

Justin

[autotec]

Well carbs are installed and primed, oil has been changed and new filter installed. I stopped counting at 60 Kicks, but the oil light finally went off. New battery installed and charged. After 40 yrs, it's finally time to wake her up. It was really undramatic, but it shows what preparation does. The bike started without a problem.

Now that it started, it's time to finish the job and make it right......

https://sohc4-forum-attachments.s3.amazonaws.com/first_start.mov

[autotec]

Before I started ripping the bike down to clean, powder coat, paint and polish everything, I thought I better put my butt in the seat to make sure everything works. I didn't go very far or fast since the tires are over 40 yrs old, but it felt good. The front brakes need attention, but I was expecting that. I ended up putting just over 2 miles on it. I found a small fuel leak, but that was just a simple re-seating of the #4 float bowl.

When I got it back in the garage, I started making a game plan out after I started playing with the chrome. I think I can save most of it, but being parked in a moisture filled garage for a lot of years really took it's toll on some things. After working on the front fender with some aluminum foil, I'm feeling pretty good with leaving things as they are. I'll still break it down, but I should be ok to leave the chrome alone. Now I just need to decide if I want to reseal the engine. I don't see any leaks yet, but I would hate to find one after a few months.

[autotec]

Well it's been a few months since I've posted a update, but there is a good reason for this. I added a new bike to the stable, a 06 Ultra that needed some attention. Now that the work needed is done to that, it's time to get back to the Honda.

I put a few more miles on the ole 72 to make sure everything worked. (it does) The first step was to remove the exhaust since it runs below the frame. Everything came off fine, but I one of the pipes has a small hole in it. I know the exhaust has been discontinued, so what is everybody replacing it with? I've searched, but didn't find anything I really liked. I would love to keep the 4 into 4, but it looks like that isn't a option.

Then there is the bars, I need something different. I talked with my uncle, and he said this is how he bought it new. Maybe they were changed at the dealership, that's my best guess since they are not factory. (I think )

Well on the jack it goes, till it's finished.

Thanks, Justin

[autotec]

Well now that summer is coming, I figured it was time to get this project going again. I was waiting on the title, and I wasn't disappointed. I just received all of the original paperwork on this bike. If you are curious what these bikes sold for when they were new, look below.

[autotec]

Original purchase.

[autotec]

And here is the repair after he laid it down in 1975. This was the last time it seen the road. It went from the dealership to the garage.... Now It's in my garage .

[Tews19]

Subscribed! How did I miss this? I'm local to you and if you want any help I'm willing.

[PeWe]

Good that engine was conserved with oil
Very few miles so no need of open engine unless the bike has been stored where it can rust. Valve seats and valves might become bad when sitting long. That will be visible when driving it. Compression test after some driving and cooled down a bit. Hot engine not nice to handle when fiddling with 2-3 plugs.

Fresh oil filter and oil.... do not overfill. I filled my CB750 with 2.6 Liter at my last oil change since all oil does not come out. Oil level on dip stick to be checked after a 10 min ride and really warm.

The documentation with the history make the bike special!

[autotec]

I can't believe more than 2 years has gone by without me touching anything on this project.

Last night I pulled it away from the wall and got it back on my motorcycle jack, I wan't to get it on the road again this summer. I'll pick up a new battery on the way home and try to remember where I left off. Time to start making a list.

[autotec]

It's stripped down. Parts are labeled and bagged. Frame has been cleaned and polished the best I'm going to get it. It's nowhere near perfect, but its pretty good for going on 50yrs old.

Time to start cleaning some parts and reassembling.

[BenelliSEI]

Nice work! I have a 1974 K4 with much the same story as yours. Guy dropped it once and parked it in 1977! It had just over 9,000 miles when I bought it. I’ve been detailing it and reusing almost every original part since day one. Whenever I do another project, if it has a nicer, original part, I use it them on the K4 and buy NOS or replica stuff for the project. Fenders, grab bar, seat and two pipes, all  came from other SOHC cb750s. This way, it’s still “original” and unrestored. I also respoked the rims when I had them off for new rubber. Bike runs beautifully and is a real favourite where ever I stop! Keep up the great work.