Topic: Cb650 Motor Swap - Need Wiring Help

[wdmcdonald]

Ok so i've started to get parts together to put my 650 motor in my 550 frame. I'm having trouble deciding what to do about wiring. I want to try and use the 550 harness so anyone that has experience with this, feel free to chime in.

After comparing the wiring harnesses it looks like the only big differences are the ignition system. the 650 has "spark units" in addition to coils and I'm not familiar with that set up. If I convert the pulse generator to a Dyna ignition could I get rid of the spark units and wire it the same way as the 550? 

If there are any other issues I might run into please let me know. Any help would be great.

Thanks

[phil71]

that 650 ignition is pretty bulletproof... simple to wire up too. Do you have the spark units?

[phil71]

p.s. the spark units are merely a small amplifier that take the very weak magnetic pulse from the pickups and make it strong enough to fire the coil off.

[wdmcdonald]

Well I don't necessarily want to swap out the ignition I was just thinking it'd easier to wire into the 550 wiring harness. I don't have any electrical components  from the 650 so that's my dilemma. Would the spark units be the only additional component I need to use my 550 harness?

[phil71]

Yep. coils should be fine. Spark units are the same on a ton of bikes from 80- so i bet you'd find them cheap. If you do get them, make sure to get a nice clean mount to frame, and use some dielectric compound to help them dissipate heat.
the magnetic pickups are still in there, right?

[phil71]

http://www.ebay.com/itm/1984-HONDA-CB650-SC-NIGHTHAWK-CDI-IGNITION-IGNITER-BOX-IGNITOR-368D-/260915971737?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item3cbfcdc699#ht_500wt_713

i'd offer him $40.. $50 if he can provide the orig plug with some pigtails coming off it so you can wire it in

[wdmcdonald]

Yep. coils should be fine. Spark units are the same on a ton of bikes from 80- so i bet you'd find them cheap. If you do get them, make sure to get a nice clean mount to frame, and use some dielectric compound to help them dissipate heat.
the magnetic pickups are still in there, right?

 Ya everything in the motor is there. Thanks for that link I'll probably pick those up. the charging system should be pretty straightforward to wire in as well right?

[phil71]

uh... well, the nighthawk had a much better rect/regulator setup.. unfortunately, they are a little pricey ($100) or so. I believe you can wire it to the 550 setup 1 for 1 and it'll work, but charging is definitely more efficient with the newer rig.

[wdmcdonald]

Ok so I've got the motor mounted in my 550 frame now. Time to figure out the wiring. I picked up a set of spark units and I think that's the only additional thing I need.

Couple questions.

1) Can I just wire the CB650 charging system directly into the 550 harness?
2) I'm assuming all I need to do for the ignition system is wire the spark units in between the pulse generator and the coils?

Any help would be much appreciated.

Thanks!

[phil71]

download a shop manual from a 1st year DOHC cb750. Follow that wiring, and you'll be in business.