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Engine swap questions

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r1trav

Engine swap questions

I have a 1975 CB750F frame with a bad motor and I also have a good and running 1980 CB750 DOHC motor. I was wanting to know if the 1980 motor will fit into the 1975 frame and if anyone has any experience with this or has seen it done.

FastCletus

Re: Engine swap questions

I am fairly certain it wont. only reason I say that is my buddy has a SOHC and he cant take his valve cover off with out engine removal whereas on my 1980 cb750 f I can.

with that being said,I have a cb 750 K frame for sale if your interested, and your 1980 engine will fit perfectly.

@FastCletus552 aka Jimmy C, buildin' rides out of Napa CA
Current Build 1980 CB 750 F
Finished Build 1975 CB 500T Cafe Racer - SOLD
2002 Ducati 998 Biposto
2005 Rossi #46 Scooter

seestheday

Re: Engine swap questions

I've heard of people doing it, but it'll take some welding. Better off just buying a DOHC frame or an SOHC engine.

1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

My cb750 video site

shinyribs

Re: Engine swap questions

Administrator

Definitely not a direct swap,but I imagine it could be done.

Like Sees' said,it'll require some fabbing.

The DOHC cam covers come off because the frame is made to allow. The SOHC's aren't setup this way from the factory.

Get some measuremets and see what up. I betcha it'll work.

cdaiscool

Re: Engine swap questions

Frames are totally different. Vetter mounts won't go between the 2, for example.

Obviously anything CAN happen, but it'd be more work than worth. But would be awesome to screw with people.

"Wait, that's got a 1974 frame... and a DOHC motor... WTF???"

Turbos, Hondas, 4-bangers, what could go wrong?

Shiny: [...] Considering the weather you've had to put up with I'd say you get an Iron Butt award and a Frozen Nipple trophy to go along with it. First time I've ever posted the word nipple... it ends here.

TOOLS1

Re: Engine swap questions

Administrator

The motor mounts are the same, but the head will hit the frame. However you could always remove those two stupid tubes that run along side the backbone. Then it would fit. Now putting a SOHC engine in a DOHC frame is too easy.
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

Talltom

Re: Engine swap questions

In reply to this post by r1trav

Question about engines, will a 92 dohc cb750 fit an old 1980 frame?