frankenbike

so now, im recovering from my first serious bike accident. bones will
mend but old bikes get written off. having extensive frontend damage
my insurance company has detirmined cost of repair is more than its
value. even tho i understand, i dont feel that way. i bought back my
'80 cb750f at the scrap price, for 'parts'. even if i could straighten
the frame, i understand, due to the law, that it could never be put
back on the road. ok. so now, i have an engine that screems, in
seriously good tune, and a whole lot o other parts that make up a
nearly whole bike. my big question is this- what model years will this
engine fit? i know of a 72 cb growin weeds behind a friends house. it
looks nice, but it would look nicer on the road. can i do it? with
little or no modification? if not a good candidate, what chasis would
be the one to take the 750 dohc? any other suggestions, frame or even
supension? '87 cbr swingarm and front end on '72 cb with '80 engine?
ive got the time to tinker before ive mended well enought ride and im
wonderin just what and how easily it can be done?
thanks for the wisdom and ideas that will be new things,
b.

 

You sure you can't get a salvage title and put it back on the road? I
have an uncle that makes a serious side income doing that with cars
around here (buys late-model salvage cars and fixes em up and resells)

 

1979, 1980, 1981 and 1982 CB750F. Maybe the CB900F and the rare
CB1100F.

Go to www.partsfish.com or bikebandit.com or any other online parts
fiche site you know of and look at parts fiches and compare any parts
numbers you can find to see what years used the same identical
frames...

Bzzzt! Forget that brain fart, unless you know of a good motorcycle
frame shop that can do major frame modifications and not wind up with a
steering head that's all twisted out of alignment.

The early models were called CB750Kxx, running from K-zero in the 1969
model to about K7 in the 1977 model. Those were single overhead cam
engines in a completely different frame than the CB750F motor needs.

There were two low frame rails preventing the mechanic from removing
the CB750Kxx valve cover without pulling the engine out of the frame.
Since the mechanic couldn't get the valve cover off, he couldn't remove
the head to do valve work. But he could adjust the valves through eight
removable caps.

If you put a CB750F motor into one of those CB750xx frames, you would
NOT be able to adjust the valves at all...

Some smart aleck riders used to cut the CB750xx lower frame rails and
install removable frame rails so they could work on the top end of the
engine without pulling it out. One idiot I knew had some pieces of
aluminum tubing that looked like they came from a piece ofr lawn
furniture bolted into his lower frame rails. I always thought Joe was
sort of retarded anyway, but when I saw that modification I knew he was
seriously stupid.

Smart alecks like Joe wound up with bent frames. The CB750F frame has
pre-bent frame rails so the valve cover can be removed with the engine
still in the frame.

Look for a CB750F rolling chassis that has NO motor in it. Home
mechanics will often get started on an engine rebuild project, have the
engine out of the frame and all apart and then they run out of time or
money or interest. The resulting "basket case" can often be bought very
cheaply.

Hey, brain farts are free until you actually start buying stuff that
won't fit together and you start trying to make something out of that
mistake.

I once installed a Jaguar engine into a Triumph sportscar. It was the
little things that made a Frankenstein Monster out of that mutant
Trumpet...