Topic: Dohc cb750f?

[nobody]

So I'm talking to this guy about two super sports he has for sale, one is a 78 and the other is an 80. Both need a tiny bit of work but are being sold for VERY fair prices. My question is this: I know the 79+ cb750s aren't used widely as cafe racers because the heads are less reliable and because they just don't have that classic look or a parts following, but how are they as bikes? Is it a bike worth owning? Is it reliable and fun? I intend to cafe the 78 750f and return my 74 750k to stock but I feel bad riding such classic bikes too frequently so I figure the 80 would be good for a daily rider/tourer... Any feedback you have would be welcomed.

[countrygreg]

I own a 1975 cb550,  and 2 1981 cb750 DOHC bikes. I think they are fun to own and just as reliable as any other 30 year old bike if properly maintained. They also have a large following, check the DOHC forums.
I do not think there is a reliability issue with the heads if the valve clearance is set to .005" and checked and adjusted at the correct intervals. The factory manual is wrong (.003") and you will burn valves and have problems with that clearance. Hope this helps.

[nobody]

It does help, I'll probably end up getting it.

[bucky katt]

the 78 is a better bet. the single cam 750s are alot easier to work on, valve adjustments only require removal of tappet covers, a 10mm wrench and a flat bladed screwdriver. the twin cam 750s are a shim/bucket setup and are ALOT more involved for a valve adjustment.

[Jay B]

Valve adjustments are more involved, but it really isn't too bad a job. You'll need a Motion Pro bucket depressor and a cheap micrometer. Another issue on the dohcs is the electronic ignition. Any loss of voltage between the battery and coils and it gets weak. Best solution is a Dyna 2000 kit from Z1. Far better than stock, and cheaper than replacing stock components. Other than that, they are great bikes.

[bryanj]

Early 750DOHC had an oiling problem which caused the sprocket seal to blow out needing the cases split to replace. There was a Mod involving replacing the oil path plate inside the sump. i have the bulletin somewhere

[nobody]

What year did the oiling problem occur and how frequently? Should I shy away from it then?

[Flying J]

I say get the 78. Just because i am biased. I have 2 SOHC 750 super sports. I dont know anything about the DOHC.

[nobody]

Well I'm for sure getting the 78, not a doubt in my mind. Should I get the dohc in addition to it though? I feel bad for racking up miles on my 74 750k and will probably feel the same about the 78 f

[YogiBear]

Yes, buy the 1980. DOHC CB750's (All makes, K,C,F) are good bikes. The motors are just as reliable as any other Honda out there on the road. There is nothing wrong with the heads, the valves need to be adjusted to .05 like mentioned above. They are fun to ride and make great power. Real world mpg for a DOHC CB750 is about 38 mpg is you ride it fairly nice.

[Bodain]

Oh.... It's a 78 F...... You might want to reconsider the DOHC...

[nobody]

I've got the 78f already. I passed on the dohc because it needed more work than I wanted to put into it, not that the 78 is any prize piece either but hopefully it will be after I put many hours into it.

[Bodain]

I did a 78 F once.. Never again!  Before and after shots. Now when I see a 78 F for sale. I just turn away.






I simply could not make it STOP smoking.  3 engines, $325.00 for a valve job, I finally surrendered to it and sold as is....

[nobody]

Well that's not good to hear. Hopefully I have better luck with mine. It didn't smoke before I started tear down, I'll cross my fingers.