CA 77 top CA 72 bottom

[Pigeonalley]

I need someone to tell me it won't work! <br /><br />I have a good top half of a CA77 new pistons .. the works but the case is shot! Some how the rear mounts were broken off and the right cover is busted. It was hit hard!<br /><br />I got a very nice complete CA72 bottom given to me.<br /><br />Can I put these two together to make a complete motor? <br /><br />The only part I'm missing for the 72 is the head. Can I use the 77 head on the 72? I would rather use the jugs, pistons and head from the 77 on the 72 case if it can be done.<br />

[bill440cars]

I know for a fact that the heads can be swapped and I don't know
of any reason that you can't use the top end of the CA77 on your
CA72. I had a 66' CB72 and installed a police model (I think it was
called CP77 or CYP77) head (that a buddy ported & polished)along
with the carbs on my CB72. After doing this, advancing the cam timing
by 1 tooth and replacing those big heavy mufflers w/ megaphones, I
had a pretty good runner (I think I should point out that I was in Japan
and in the USAF at the time and you couldn't get the aftermarket high
perf. parts there) I could beat the average Super Hawk with it. Myself,
I now have a 63' CB77 that someone stuck a CA77 into and it needs A
LOT of work. I hope to either come up with a CB77 motor or gather
parts and convert the CA motor to a CB and build it up. I've got some
ideas of my own and some from others that I want to use. If all goes
well, I'll let you guys in on it later. Good luck wth your bike and I'll
catch you later on, Bill

[joeweir1]

Isn't the combustion chamber smaller on the CA72 than the CA77?

[bill440cars]

Isn't the combustion chamber smaller on the CA72 than the CA77?

Yes, I'm sure it is and I believe the valves are smaller in the
CA72 head. That won't keep it from working. It may require rejetting th
carb. unless the CAcarb can be gotten also. Later on, Bill

[joeweir1]

CA77 cylinders do not fit down in the jug holes of a CA72. I measured them and slid one down on a CA72 jug to confirm.I think valves are the same. I will get some of each out to compare.

[bill440cars]

CA77 cylinders do not fit down in the jug holes of a CA72. I measured them and slid one down on a CA72 jug to confirm.I think valves are the same. I will get some of each out to compare.

joeweir1, The cylinders may not go down into the CA72 crankcase without some machine work, I wasn't sure about that. I knew the head would fit because I'd done that. How much difference is there? To me, it seems like the main concern would be how close you would come to the cylinder studs
(and what the cost would be) by having machine work done. If it wouldn't be too cotly compared to the cost of what you'd need to have a complete CA72
motor and wouldn't cause a problem with the cylinder studs, I'd say go for it.
Of course, the call is up to the owner. Anyone else want to kick in some input here, I'm sure he'd appreciate it. Later on, Bill

[bill440cars]

CA77 cylinders do not fit down in the jug holes of a CA72. I measured them and slid one down on a CA72 jug to confirm.I think valves are the same. I will get some of each out to compare.

joeweir1, The cylinders may not go down into the CA72 crankcase without some machine work, I wasn't sure about that. I knew the head would fit because I'd done that. How much difference is there? To me, it seems like the main concern would be how close you would come to the cylinder studs
(and what the cost would be) by having machine work done. If it wouldn't be too cotly compared to the cost of what you'd need to have a complete CA72
motor and wouldn't cause a problem with the cylinder studs, I'd say go for it.
Of course, the call is up to the owner. Anyone else want to kick in some input here, I'm sure he'd appreciate it. Later on, Bill

I just reread the your post joeweir1, you are talking about the cylinders fitting into the cranksase aren't you? After I reread it, I wasn't sure. When I put a CP77 head on my CB72, it didn't require any machine work, it was a bolt on procedure.