Topic: Question about 1972 CB500 and 1979 CB650 electrics

[arncruz]

Hi Fellas,  I had recently acquired a 1972 CB500.  It was mostly complete except for a tank and seat.  The engine is stuck but was able to get it moving.  The electrics are complete but the wires and the connectors were rotted out.  I have a 1979 CB650 parts bike with a running engine and a pretty good wiring harness and electrical system.  I was thinking of using the electrics from my CB650 and using it on the CB500.  Just wondering if this is possible.  Any thoughts? My plan is to use hand controls from the CB650 as well.

Thanks
aRnold

[nicks2319]

Might as well use the 650 engine too. Look up 650 swaps, it requires you swap the 500 electronics for the 650.

[arncruz]

nicks, are the engine mounts the same on the CB650 as they are on the CB500?  Also how does swapping and engine work with the DMV?  The bike has no title and i already set up an appointment with our CHP (california highway patrol) for a vin verification since it looks like its been out of system for some time.

Thanks

[CBGhia]

The bikes are titled by the VIN on the neck, not the engine number.

The mounts are the same and the 650 makes WAY more power than a stock 500.  I like the 500 frame more than the 650 frame. 

I have a 650 engine that I am about to swap into my 550. 

[rb550four]

I don't know about Cali DMV rules and regs but , the switch from 500 to 650 is almost a no brainer. there will be some modifications that will come into play though,
engine mounts are the same....take the lids off the top of the engine and slide it in bolts up exactly the same.
 1) the wiring will work.....I use the 60 battery box under the seat , not in the 500's position but it does mount up on the 500 air box forward mount,the rear will line up on the bottonside of th frame on the rear 500 airbox mout, if you have 1 extra forward 500 engine mount plate it will bolt it all together and save you some irritation
 The electric panel for the 650 goes on the left side of the battery box...I cut the tool box off it flip it over and mount the rectifier onto that.
 an 81 airbox is a tight fit and needs to be installed with the rear inner fender off, I haven't gotten to play with my 78 650 yet so I don't know what the airbox is like
 the 2 cdi units will fit along side of the battery box mounted on the top right ,just over the air box , isolate the mounts with rubber gromets and don't let them touch anything else
   That should take care of under the seat.
2)  I use 2 sections of 6mm threaded rod and 4 6mm connectors for spacers to hang the 650 coils on ....the rear hole for the coil mount will have to drilled in the frame for a proper fit.
 Wire it as you would a 650 with the 650 harness.
3) The 650 chain is larger than the 500, I use a 650 wheel and swingarm because the larger wheel fits better in the inch and some longer 650 swingarrm, but the frame would have to be drilled for the larger 650 swing arm bolt, and I don't know what everyone else does.
4) if you are using the chrome covers on the 650 carbs you will have to trim out the sidecovers on any K model, the 50 F's are different, you wouldn't have to trim the side covers on those.
5) the front suspension is upgraded on the 650....the neck is the same as the 500...if you nhave the suspension it's an easy swap.
6)I use zip ties to keep the clutch cable to the frame as there are no welded stays for that on a 500 frame.
                                                                                                                               RB

                                                                                                                               

[SOHC4 Cafe Racer Fan]

In California, the DMV registers the serial number of the engine along with the VIN on the frame neck.  I've been told you can do an engine swap officially, by having the serial number for the engine changed or just swap the motor.  There is no further check to the engine serial number if you sell the bike to another California buyer, and most states do not register the engine number.  So, it's up to you.

I am doing the swap into a 550 frame.  My wire harness is not in such good shape, but the motor is.  I do not know sources for repro or NOS wiring harnesses so I will likely go Motogadget M-Unit on this bike. 

[arncruz]

Thanks guys.  I think ill do the engine swap.  Anyone have pictures of this?