76 kz400 engine on a 81 kz440 ltd - will it work?

So I have a 81 kz440 ltd and have been looking for an engine for it but haven't really had any luck. A buddy of mine comes up and says he has a 76 kz400 engine that just needs points and condensor and that it should work on my bike. I am curious if it will and how involved the swap would be? I am fairly new to bikes so please bare with me. Thank you in advance for any information any of you have.

It seems to me you are here to glean some information to make a buck.
All the information is on this site to provide the answer to your questions concerning this motorcycle.
All you have to do is use the search button. Since you have not done that I'll give you the answer.
The 400 will bolt straight in to the 440 frame {and visa versa} except for the top mount.
Have a good day.

You did not mention what state the original engine is in - how much of it you have, etc.

You can use the earlier KZ400 engine but you will have to use everything including carbs, carb holders, etc. The airbox from the earlier bike will not fit the LTD so you'll have to come up with something to go from the carbs to the existing airbox. I have seen some folks use shock boots and similar things.

I believe that 1981 was when they started using electronic ignition. It would be a good idea to use the electronic ignition components from the 81 (if you have them) instead of the points/condensor of the 76. It is a pretty simple swap - retrofitting the later electronic ignition to earlier bikes (74-80) is pretty common.

The 76 uses a different style of stator than the 81 so you will have to swap over some of the electronics like rectifier or switch over to a more modern rectifier/regulator combo.

I actually still have the engine for the 81 and it runs, it just needs the bottom end rebuilt and it was suggested to me swapping out the engine would be cheaper and more time efficient. The 400 that I can get I was told just needs points and a condensor. So basically what your saying is i can avoid having to buy points and a condensor by using the parts off my 81?

Yes, the electronic ignition does not use points and condenser. If you use the electronic ignition from you 81 then you'll be all set. IIRC electronic ignition started in 1981. Pull off your ignition cover of the 81 engine and take a look inside to confirm.

Like diggerdanh said,

you will need the carbs from the 1976 motor, or some other custom option.

You will need a regulator and rectifier (or modern combo version) specifically for the 1976 motor. You can't use the 81 regulator rectifier with the 1976 motor. (And I'm pretty sure you can't swap the alternator between motors.)

You will want the electronic ignition from the 81, if it came with it. That should swap to the 1976 motor.

And yes, all of this will be easier/cheaper than trying to rebuild the 1981 motor.

If you are not using the airbox, the 1976 carbs will need rejetting, or you can swap to simpler carbs if you don't have the 1976 carbs already. There is also a single VM carb option using a 1-into-2 manifold. That will require some googling and tuning to get right. But the old 1976 carbs are going to need a lot of fiddling to get right, as they are pretty complicated, so there is probably no super easy shortcut there.

loudhvx wrote: Like diggerdanh said,

you will need the carbs from the 1976 motor, or some other custom option.

You will need a regulator and rectifier (or modern combo version) specifically for the 1976 motor. You can't use the 81 regulator rectifier with the 1976 motor. (And I'm pretty sure you can't swap the alternator between motors.)

You will want the electronic ignition from the 81, if it came with it. That should swap to the 1976 motor.

And yes, all of this will be easier/cheaper than trying to rebuild the 1981 motor.

If you are not using the airbox, the 1976 carbs will need rejetting, or you can swap to simpler carbs if you don't have the 1976 carbs already. There is also a single VM carb option using a 1-into-2 manifold. That will require some googling and tuning to get right. But the old 1976 carbs are going to need a lot of fiddling to get right, as they are pretty complicated, so there is probably no super easy shortcut there.

so the carbs off my 81 will not work? The bike currently is not running an airbox, it's running Unis and the carbs have already been rejetted for that. I will have to source out a regulator rectifier and an alternator for a 76 then and yes my 81 has the electronic ignition, it's not a kick start.

I just want to make sure I do this right since this will be going to a buddy of mine and I don't want to give him something that's gonna to run like shit. and to the first person that comment on here, this is a not a deal for financial gain. This is a goods for goods deal and I am not looking to give him something not running or driveable. I will search for some stuff on here now that I actually found the search feature since it's not a bar like it is in other forums and I thank everyone that has chimed in their knowledge to give me some insight ad direction.

If you have both motors, check to see if the carb holders are the same. They might be different sizes, or the bolt spacing may be different. It's been a long time since I've worked on the 76 Kz400 and 440's, so I could be wrong, but I thought there was some difference.

The 1976 400 (and other 400's) motor, from what I remember uses an alternator cover with a slightly different bolt pattern from the newer motors, so you can't swap covers, and the cover is needed to hold the field coil. The later motors don't use a filed-coil type alternator.

I found an image I created a few years ago.


And here are some quick notes I made for myself back then (hopefully it is correct):
PM means permanent-magnet as opposed to the type that uses an electro-magnet, also known as field coil.

The 400's (except for the B, C, and H) use excited field alternator with cover 14031-1007-80. This spans over many years and overlaps with the PM alternator years.

The 400 B and H use PM alternator with cover 14031-1023.
The 400 C uses same PM alternator with cover 14031-1001-80.

Some 440's some use PM alternators with cover 14031-1023.
Some 440's use the same PM alternator with cover 14031-1083.

The two cover types won't interchange on a motor, and the two types of alternators require different cover types.
The E field cover has 10 holes.
The PM cover has 11 holes, and they are in different places.

The ends of the cranksharft may also be different, which would make the swap very difficult.

These notes are not complete!
Need complete list of stator, flywheel, and cover numbers.

awesome....thank you. Basically I am not really gonna know much until I have both engines sitting side by side and I can start comparing and piecing together it seems. This is definitely a good starting point so now I just need to get the 400 and get the 440 out of the frame and just go from there. Any other information you may think of or come across I will be checking this daily. And thank you again.

I'll keep an eye on this thread. I hope to find a decent 400/440 project at some point. My old 400 was one of my favorite bikes and got me hooked on KZ's (after working on a few Hondas).

so here's a curious question....it would still work if i wanted to keep it kick start and not use the electronic ignition wouldn't it?

The starter function and ignition function are not really related.

The electronic ignition can be used on any of the motors. The only issue, when retrofitting the electronic ignition to an older motor might be timing. But you can adjust that as necessary by elongating the mounting holes, or re-setting the rotor slug on the advancer rotor hub.

The electronic advance needs the coil that goes with it. So you need to transfer everything...the advancer/rotor, pickup plate, igniter box, and coil.