New CB750F Owner

[Drummerking55]

Just brought a 750 supersport home. Can't wait to dig into it. One owner with 5000 miles on it. I am expecting it to be Easy to get running. With that said, does anyone have any good things I should look at before I fire it up for the first time. It has not been run in 15 years. Also I would like to post a pic but don't see the option too

 

[SurferD]

Great find. The F models have some nice improvements from the K's.
I use Photobucket for pics.
Check compression and valve clearances before trying to start it.

 

[Drummerking55]

 

[SurferD]

great looking bike looks clean.
Where'd you find if and how much did you pay?

 

[Drummerking55]

Guy in my home town had it. I got it for next to nothing. Did some trading for it. He bought it new in 1980

 

[amc49]

Lotta pieces been messed with there for 5000 miles.......... '82 front fender and turn signals not OEM as well as looks like pipes off a 900. Looks like heavy carb flooding on sprocket cover, the drain hoses are missing. Bars and mirrors different too.

I'd bet there's more to the story than just 5K miles...............adjust the valves, most never do it then the motor runs like crap and they tear into the carbs to mess those up too...........compression check to get the unhappy news. Why they are never running when you get them.

 

[Drummerking55]

K&N super bike bars. And he said he liked the front fender for the small flair on it. I don't doubt his story on the 5000 miles but unfortunately it looks like it went through a flood. So I'm in for some work or maybe a new motor. Tore it down yesterday and I think I'm going to have to bore it out

 

[Drummerking55]

Some bad findings on the cb750 project. The cylinders are rusted so bad I am afraid they won't be able to be bored . So I guess I need to look into new ones. The bottom end looks good . I think someone must have drained the oil and whatever water got in the cylinders out right after the flood because there is no rust that I can see in the case. I am prob going to split the case just to make sure. Does anyone know if a sohc cylinder set fits the dohc. There is a guy local that would sell me one if it did. I'll post a pic of the worst cylinder but apon inspection of the valves they are in very good shape. A little discoloration in the bottoms but the seats and the shafts are perfect. I will probably do a valve hone job on them to refresh them though

 

[Drummerking55]

 

[SurferD]

Wow that's really bad

 

[Drummerking55]

Yeah just the one was really bad. I just bought a new cylinder head and Pistons off eBay so until it gets here I will be reconditioning the valves. Does anyone have thoughts on if a bike in a water for about a day would ruin the electronics .

 

[Drummerking55]

 

[Drummerking55]

The later pics are of the cylinders I got off eBay

 

[Chris in Dorset England]

That looks nasty and expensive

 

[dirtdigger]

Just so you know...no the sohc cylinder does not fit the dohc.

 

[Drummerking55]

Ok that k you. I see that they have different tensioned among other things I'm sure. Quick question. I pulled the head and the cylinders off . Inside the crank case looks clean but it will only rotate about half way around. Is there something common that could be holding it up or do I need to split the case

 

[dirtdigger]

If it was in a flood split the case, you dont know what found its way in there. Could be a lot of hidden damage/rust in tranny bearings etc.

 

[amc49]

Splitting cases................don't miss the bolts on TOP of motor that have to come out too. And the alt rotor MUST pull off to completely separate the cases.

 

[Drummerking55]

So I split the case and all looks good. I found out that when I was trying to rotate it before it was binding on the cam chain. Looked over the bearings and did not find any rust. Reassembled the case after cleaning the sealing area and applying new sealant so now I am waiting on the gasket kit and the head and Pistons that I ordered. I am wondering after cleaning the Pistons they actually look pretty good. The rings look good as well. Should I just order new rings or is it possible to reuse them as long as I deglaze and crosshatch the replacement cylinders properly. This is assuming that the piston end gaps are all good. I still have to check them once it's ready to go.

 

[dirtdigger]

No you can not reuse piston rings.